Nick Connor

Stainless Steels

In metallurgy, stainless steel is a steel alloy with at least 10.5% chromium with or without other alloying elements and a maximum of 1.2% carbon by mass. Stainless steels, also known as inox steels or inox from French inoxydable (inoxidizable), are steel alloys, which are very well known for their corrosion resistance, which increases with increasing chromium content. Corrosion resistance may also be enhanced by nickel and molybdenum additions. The resistance of these metallic alloys to the chemical effects of corrosive  agents is based on passivation. For passivation to occur and remain stable, the Fe-Cr alloy must have a minimum chromium content of about 10.5% by weight, above which passivity can occur and below which it is impossible. Chromium can be used as a hardening element and is frequently used with a toughening element such as nickel to produce superior mechanical properties.

Uses of Stainless Steels – Applications

Strength and corrosion resistance of stainless steel often make it the material of choice in transportation and processing equipment, engine parts, and firearms. Most of the structural applications occur in the chemical and power engineering industries, which account for more than third of the market for stainless steel products. The wide variety of applications includes nuclear reactor vessels, heat exchangers. The body of the reactor vessel is constructed of a high-quality low-alloy carbon steel, but all surfaces that come into contact with reactor coolant (highly corrosive due to the presence of boric acid) are clad with a minimum of about 3 to 10 mm of austenitic stainless steel in order to minimize corrosion.

Stainless steel can be rolled into sheets, plates, bars, wire, and tubing. Stainless steels do not need to be painted or coated, which makes them suitable for use in applications where cleanliness is required: in cookware, cutlery and surgical instruments.

Types of Stainless Steels

Stainless steel is a generic term for a large family of corrosion resistant alloys containing at least 10.5% chromium and  may contain other alloying elements. There are numerous grades of stainless steel with varying chromium and molybdenum contents and with varying crystallographic structure to suit the environment the alloy must endure. Stainless steels can be divided into five categories:

• Ferritic stainless steels. In ferritic stainless steels, carbon is kept to low levels (C<0.08%) and the chromium content can range from 10.50 to 30.00%. They are usually limited in use to relatively thin sections due to lack of toughness in welds. Moreover, they have relatively poor high-temperature strength. Ferritic steels are chosen for their resistance to stress corrosion cracking, which makes them an attractive alternative to austenitic stainless steels in applications where chloride-induced SCC is prevalent.
• Austenitic stainless steels. Austenitic stainless steels contain between 16 and 25% Cr and can also contain nitrogen in solution, both of which contribute to their relatively high corrosion resistance. Austenitic stainless steels have the best corrosion resistance of all stainless steels and they have excellent cryogenic properties, and good high-temperature strength. The best known grade is AISI 304 stainless, which contains both chromium (between 15% and 20%) and nickel (between 2% and 10.5%) metals as the main non-iron constituents. 304 stainless steel has excellent resistance to a wide range of atmospheric environments and many corrosive media. These alloys are usually characterized as ductile, weldable, and hardenable by cold forming.
• Martensitic stainless steels. Martensitic stainless steels are similar to ferritic steels in being based on chromium but have higher carbon levels up as high as 1%. They are sometimes classified as low-carbon and high-carbon martensitic stainless steels. They have moderate corrosion resistance, but are considered hard, strong, slightly brittle. They are magnetic and they can be nondestructively tested using the magnetic particle inspection method, unlike austenitic stainless steel.  A common martensitic stainless is AISI 440C, which contains 16 to 18% chromium and 0.95 to 1.2% carbon. Grade 440C stainless steel is used in the following applications: gage blocks, cutlery, ball bearings and races, molds and dies, knives.
• Duplex Stainless Steels. Duplex stainless steels, as their name indicates, are a combination of two of the main alloy types. They have a mixed microstructure of austenite and ferrite, the aim usually being to produce a 50/50 mix, although in commercial alloys the ratio may be 40/60.  Their corrosion resistance is similar to their austenitic counterparts, but their stress-corrosion resistance (especially to chloride stress corrosion cracking), tensile strength, and yield strengths (roughly twice the yield strength of austenitic stainless steels) are generally superior to that of the austenitic grades. Superduplex steels have enhanced strength and resistance to all forms of corrosion compared to standard austenitic steels. Common uses are in marine applications, petrochemical plant, desalination plant, heat exchangers and papermaking industry. Today, the oil and gas industry is the largest user and has pushed for more corrosion resistant grades, leading to the development of superduplex steels.
• PH Stainless Steels. PH stainless steels (precipitation-hardening) contain around 17% chromium and 4% nickel. These steels can develop very high strength through additions of aluminum, titanium, niobium, vanadium, and/or nitrogen, which form coherent intermetallic precipitates during a heat treatment process referred to as heat aging. Of all of the available stainless grades, they generally offer the greatest combination of high strength coupled with excellent toughness and corrosion resistance.  They are as corrosion resistant as austenitic grades. Common uses are in the aerospace and some other high-technology industries.

Aluminium Alloys

High purity aluminium is a soft material with the ultimate strength of approximately 10 MPa, which limits its usability in industrial applications. Aluminium of commercial purity (99-99.6%) becomes harder and stronger due to the presence of impurities, especially of Si and Fe. But when alloyed, aluminium alloys are heat treatable, which significantly changes theri mechanical properties.

Aluminium alloys are based on aluminium, in which the main alloying elements are Cu, Mn, Si, Mg, Mg+Si, Zn. Aluminium alloy compositions are registered with The Aluminum Association. The aluminium alloys are divided into 9 families (Al1xxx to Al9xxx). The different families of alloys and the major alloying elements are:

• 1xxx: no alloying elements
• 2xxx: Copper
• 3xxx: Manganese
• 4xxx: Silicon
• 5xxx: Magnesium
• 6xxx: Magnesium and silicon
• 7xxx: Zinc, magnesium, and copper
• 8xxx: other elements which are not covered by other series

There are also two principal classifications, namely casting alloys and wrought alloys, both of which are further subdivided into the categories heat-treatable and non-heat-treatable. Aluminium alloys containing alloying elements with limited solid solubility at room temperature and with a strong temperature dependence of solid solubility (for example Cu) can be strengthened by a suitable thermal treatment (precipitation hardening). The strength of heat treated commercial Al alloys exceeds 550 MPa.

Mechanical properties of aluminium alloys highly depend on their phase composition and microstructure. High strength can be achieved among others by introduction of a high volume fraction of fine, homogeneously distributed second phase particles and by a refinement of the grain size. In general, aluminium alloys are characterized by a relatively low density (2.7 g/cm³ as compared to 7.9 g/cm³ for steel), high electrical and thermal conductivities, and a resistance to corrosion in some common environments, including the ambient atmosphere. The chief limitation of aluminum is its low melting temperature (660°C), which restricts the maximum temperature at which it can be used. For general production the 5000 and 6000 series alloys provide adequate strength combined with good corrosion resistance, high toughness and ease of welding.

Aluminium and its alloys are used widely in aerospace, automotive, architectural, lithographic, packaging, electrical and electronic applications. It is the prime material of construction for the aircraft industry throughout most of its history. About 70% of commercial civil aircraft airframes are made from aluminium alloys, and without aluminium civil aviation would not be economically viable. Automotive industry now includes aluminium as engine castings, wheels, radiators and increasingly as body parts. 6111 aluminium and 2008 aluminium alloy are extensively used for external automotive body panels. Cylinder blocks and crankcases are often cast made of aluminium alloys.

Properties of Stainless Steel vs Aluminium Alloy

Material properties are intensive properties, that means they are independent of the amount of mass and may vary from place to place within the system at any moment. The basis of materials science involves studying the structure of materials, and relating them to their properties (mechanical, electrical etc.). Once a materials scientist knows about this structure-property correlation, they can then go on to study the relative performance of a material in a given application. The major determinants of the structure of a material and thus of its properties are its constituent chemical elements and the way in which it has been processed into its final form.

Density of Stainless Steel vs Aluminium Alloy

Density of typical aluminium alloy is 2.7 g/cm³ (6061 alloy).

Density of typical stainless steel is 8.0 g/cm³ (304 steel).

Density is defined as the mass per unit volume. It is an intensive property, which is mathematically defined as mass divided by volume:

ρ = m/V

In words, the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance. The standard SI unit is kilograms per cubic meter (kg/m³). The Standard English unit is pounds mass per cubic foot (lbm/ft³).

Since the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance, it is obvious, the density of a substance strongly depends on its atomic mass and also on the atomic number density (N; atoms/cm³),

• Atomic Weight. The atomic mass is carried by the atomic nucleus, which occupies only about 10^-12 of the total volume of the atom or less, but it contains all the positive charge and at least 99.95% of the total mass of the atom. Therefore it is determined by the mass number (number of protons and neutrons).
• Atomic Number Density. The atomic number density (N; atoms/cm³), which is associated with atomic radii, is the number of atoms of a given type per unit volume (V; cm³) of the material. The atomic number density (N; atoms/cm³) of a pure material having atomic or molecular weight (M; grams/mol) and the material density (⍴; gram/cm³) is easily computed from the following equation using Avogadro’s number (N_A = 6.022×10²³ atoms or molecules per mole):
• Crystal Structure. Density of crystalline substance is significantly affected by its crystal structure. FCC structure, along with its hexagonal relative (hcp), has the most efficient packing factor (74%). Metals containing FCC structures include austenite, aluminum, copper, lead, silver, gold, nickel, platinum, and thorium.

Mechanical Properties of Stainless Steel vs Aluminium Alloy

Materials are frequently chosen for various applications because they have desirable combinations of mechanical characteristics. For structural applications, material properties are crucial and engineers must take them into account.

Strength of Light Stainless Steel vs Aluminium Alloy

In mechanics of materials, the strength of a material is its ability to withstand an applied load without failure or plastic deformation. Strength of materials basically considers the relationship between the external loads applied to a material and the resulting deformation or change in material dimensions. Strength of a material is its ability to withstand this applied load without failure or plastic deformation.

Ultimate Tensile Strength

Ultimate tensile strength of 6061 aluminium alloy depends greatly on the temper of the material, but for T6 temper it is about 290 MPa.

Ultimate tensile strength of stainless steel – type 304L is 485 MPa.

Ultimate tensile strength of ferritic stainless steel – Grade 430 is 480 MPa.

Ultimate tensile strength of martensitic stainless steel – Grade 440C is 760 MPa.

The ultimate tensile strength is the maximum on the engineering stress-strain curve. This corresponds to the maximum stress that can be sustained by a structure in tension. Ultimate tensile strength is often shortened to “tensile strength” or even to “the ultimate.”  If this stress is applied and maintained, fracture will result. Often, this value is significantly more than the yield stress (as much as 50 to 60 percent more than the yield for some types of metals). When a ductile material reaches its ultimate strength, it experiences necking where the cross-sectional area reduces locally. The stress-strain curve contains no higher stress than the ultimate strength. Even though deformations can continue to increase, the stress usually decreases after the ultimate strength has been achieved. It is an intensive property; therefore its value does not depend on the size of the test specimen. However, it is dependent on other factors, such as the preparation of the specimen, the presence or otherwise of surface defects, and the temperature of the test environment and material. Ultimate tensile strengths vary from 50 MPa for an aluminum to as high as 3000 MPa for very high-strength steels.

Yield Strength

Yield strength of 6061 aluminium alloy depends greatly on the temper of the material, but for T6 temper it is about 240 MPa.

Yield strength of stainless steel – type 304L is  170 MPa.

Yield strength of ferritic stainless steel – Grade 430 is  310 MPa.

Yield strength of martensitic stainless steel – Grade 440C is 450 MPa.

The yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning plastic behavior. Yield strength or yield stress is the material property defined as the stress at which a material begins to deform plastically whereas yield point is the point where nonlinear (elastic + plastic) deformation begins. Prior to the yield point, the material will deform elastically and will return to its original shape when the applied stress is removed. Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible. Some steels and other materials exhibit a behaviour termed a yield point phenomenon. Yield strengths vary from 35 MPa for a low-strength aluminum to greater than 1400 MPa for very high-strength steels.

Young’s Modulus of Elasticity

Young’s modulus of elasticity of 6061 aluminium alloy is about 69 GPa.

Young’s modulus of elasticity of ferritic stainless steel – Grade 430 is 220 GPa.

Young’s modulus of elasticity of martensitic stainless steel – Grade 440C is 200 GPa.

Young’s modulus of elasticity of duplex stainless steels – SAF 2205 is 200 GPa.

The Young’s modulus of elasticity is the elastic modulus for tensile and compressive stress in the linear elasticity regime of a uniaxial deformation and is usually assessed by tensile tests. Up to a limiting stress, a body will be able to recover its dimensions on removal of the load. The applied stresses cause the atoms in a crystal to move from their equilibrium position. All the atoms are displaced the same amount and still maintain their relative geometry. When the stresses are removed, all the atoms return to their original positions and no permanent deformation occurs. According to the Hooke’s law, the stress is proportional to the strain (in the elastic region), and the slope is Young’s modulus. Young’s modulus is equal to the longitudinal stress divided by the strain.

Hardness of Stainless Steel vs Aluminium Alloy

Brinell hardness of 6061 aluminium alloy depends greatly on the temper of the material, but for T6 temper it is approximately 95 MPa.

Brinell hardness of ferritic stainless steel – Grade 430 is approximately 180 MPa.

Brinell hardness of martensitic stainless steel – Grade 440C is approximately 270 MPa.

Brinell hardness of duplex stainless steels – SAF 2205 is approximately 217 MPa.

Rockwell hardness test is one of the most common indentation hardness tests, that has been developed for hardness testing. In contrast to Brinell test, the Rockwell tester measures the depth of penetration of an indenter under a large load (major load) compared to the penetration made by a preload (minor load). The minor load establishes the zero position. The major load is applied, then removed while still maintaining the minor load. The difference between depth of penetration before and after application of the major load is used to calculate the Rockwell hardness number. That is, the penetration depth and hardness are inversely proportional. The chief advantage of Rockwell hardness is its ability to display hardness values directly. The result is a dimensionless number noted as HRA, HRB, HRC, etc., where the last letter is the respective Rockwell scale.

The Rockwell C test is performed with a Brale penetrator (120°diamond cone) and a major load of 150kg.

Thermal Properties of Stainless Steel vs Aluminium Alloy

Thermal properties of materials refer to the response of materials to changes in their thermodynamics/thermodynamic-properties/what-is-temperature-physics/”>temperature and to the application of heat. As a solid absorbs thermodynamics/what-is-energy-physics/”>energy in the form of heat, its temperature rises and its dimensions increase. But different materials react to the application of heat differently.

Heat capacity, thermal expansion, and thermal conductivity are properties that are often critical in the practical use of solids.

Melting Point of Stainless Steel vs Aluminium Alloy

Melting point of 6061 aluminium alloy is around 600°C.

Melting point of stainless steel – type 304 steel is around 1450°C.

Melting point of ferritic stainless steel – Grade 430 steel is around 1450°C.

Melting point of martensitic stainless steel – Grade 440C steel is around 1450°C.

In general, melting is a phase change of a substance from the solid to the liquid phase. The melting point of a substance is the temperature at which this phase change occurs. The melting point also defines a condition in which the solid and liquid can exist in equilibrium.

Thermal Conductivity of Stainless Steel vs Aluminium Alloy

The thermal conductivity of 6061 aluminium alloy is 150 W/(m.K).

The thermal conductivity of stainless steel – type 304 is 20 W/(m.K).

The thermal conductivity of ferritic stainless steel – Grade 430 is 26 W/(m.K).

The thermal conductivity of martensitic stainless steel – Grade 440C is 24 W/(m.K).

The heat transfer characteristics of a solid material are measured by a property called the thermal conductivity, k (or λ), measured in W/m.K. It is a measure of a substance’s ability to transfer heat through a material by conduction. Note that Fourier’s law applies for all matter, regardless of its state (solid, liquid, or gas), therefore, it is also defined for liquids and gases.

The thermal conductivity of most liquids and solids varies with temperature. For vapors, it also depends upon pressure. In general:

Most materials are very nearly homogeneous, therefore we can usually write k = k (T). Similar definitions are associated with thermal conductivities in the y- and z-directions (ky, kz), but for an isotropic material the thermal conductivity is independent of the direction of transfer, kx = ky = kz = k.

See above:
Alloys

Steels

Steels are iron–carbon alloys that may contain appreciable concentrations of other alloying elements. Adding a small amount of non-metallic carbon to iron trades its great ductility for the greater ductility. Due to its very-high strength, but still substantial toughness, and its ability to be greatly altered by heat treatment, steel is one of the most useful and common ferrous alloy in modern use. There are thousands of alloys that have different compositions and/or heat treatments. The mechanical properties are sensitive to the content of carbon, which is normally less than 1.0 wt%. According ot AISI classification, carbon steel is broken down into four classes based on carbon content.

Types of Steels – Classification Based on Composition

• Low-carbon Steels. Low-carbon steel, also known as mild steel is now the most common form of steel because its price is relatively low while it provides material properties that are acceptable for many applications. Low-carbon steel contains approximately 0.05–0.25% carbon making it malleable and ductile. Mild steel has a relatively low tensile strength, but it is cheap and easy to form; surface hardness can be increased through carburizing. Typical applications include automobile body components, structural shapes (e.g., I-beams, channel and angle iron), and sheets that are used in pipelines, buildings. For example, A36 steel is a common structural steel in the United States. Low-carbon steel sheets used for car body applications, for example, are subjected to a variety of forming operations, including deep drawing. Microstructures consist of ferrite and pearlite constituents. As a consequence, these alloys are relatively soft and weak but have outstanding ductility and toughness. In addition, they are machinable, weldable, and, of all steels, are the least expensive to produce. Density of this metal is 7861.093 kg/m³ (0.284 lb/in³) and the tensile strength is a maximum of 500 MPa (72500 psi).
• Medium-carbon Steels. Medium-carbon steel has approximately 0.3–0.6% carbon content. These alloys may be heat-treated by austenitizing, quenching, and then tempering to improve their mechanical properties. They are most often utilized in the tempered condition, having microstructures of tempered martensite. Medium-carbon steel balances ductility and strength and has good wear resistance. This grade of steel is mostly used in the production of machine components, shafts, axles, gears, crankshafts, coupling and forgings, could also be used in rails and railway wheels and other machine parts and high-strength structural components calling for a combination of high strength, wear resistance, and toughness. For example, a 1040 steel is a plain carbon steel containing 0.40 wt% C. Typical uses of this type of steel include machine, plow, and carriage bolts, tie wire, cylinder head studs, and machined parts, U-bolts, concrete reinforcing rods, forgings.
• High-carbon Steels. High-carbon steel has approximately 0.60 to 1.00% carbon content. Hardness is higher than the other grades but ductility decreases. They are almost always used in a hardened and tempered condition and, as such, are especially wear resistant and capable of holding a sharp cutting edge. Therefore, high carbon steels could be used for springs, rope wires, hammers, screwdrivers, wrenches and knives. The 10xx series (e.g. 1095 steel) is the most popular choice for carbon steel used in knives as well as katanas. AISI 1095 carbon steel is brittle, and has high hardness and strength. 1095 steel, when used in knives, holds a great edge and is very easy to sharpen. However, the properties of this type of steel give it a tendency to easily rust if not oiled and deliberately cared for.
• Ultra-high-carbon Steels. Ultra-high-carbon steel has approximately 1.25–2.0% carbon content. Steels that can be tempered to great hardness. This grade of steel could be used for hard steel products, such as truck springs, metal cutting tools and other special purposes like (non-industrial-purpose) knives, axles or punches. Most steels with more than 2.5% carbon content are made using powder metallurgy.

Properties of Mild Steel vs Medium vs High-carbon Steel

Material properties are intensive properties, that means they are independent of the amount of mass and may vary from place to place within the system at any moment. The basis of materials science involves studying the structure of materials, and relating them to their properties (mechanical, electrical etc.). Once a materials scientist knows about this structure-property correlation, they can then go on to study the relative performance of a material in a given application. The major determinants of the structure of a material and thus of its properties are its constituent chemical elements and the way in which it has been processed into its final form.

Density of Mild Steel vs Medium vs High-carbon Steel

Density of typical steel is 8.05 g/cm³.

Density is defined as the mass per unit volume. It is an intensive property, which is mathematically defined as mass divided by volume:

ρ = m/V

In words, the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance. The standard SI unit is kilograms per cubic meter (kg/m³). The Standard English unit is pounds mass per cubic foot (lbm/ft³).

Since the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance, it is obvious, the density of a substance strongly depends on its atomic mass and also on the atomic number density (N; atoms/cm³),

• Atomic Weight. The atomic mass is carried by the atomic nucleus, which occupies only about 10^-12 of the total volume of the atom or less, but it contains all the positive charge and at least 99.95% of the total mass of the atom. Therefore it is determined by the mass number (number of protons and neutrons).
• Atomic Number Density. The atomic number density (N; atoms/cm³), which is associated with atomic radii, is the number of atoms of a given type per unit volume (V; cm³) of the material. The atomic number density (N; atoms/cm³) of a pure material having atomic or molecular weight (M; grams/mol) and the material density (⍴; gram/cm³) is easily computed from the following equation using Avogadro’s number (N_A = 6.022×10²³ atoms or molecules per mole):
• Crystal Structure. Density of crystalline substance is significantly affected by its crystal structure. FCC structure, along with its hexagonal relative (hcp), has the most efficient packing factor (74%). Metals containing FCC structures include austenite, aluminum, copper, lead, silver, gold, nickel, platinum, and thorium.

Mechanical Properties of Mild Steel vs Medium vs High-carbon Steel

Materials are frequently chosen for various applications because they have desirable combinations of mechanical characteristics. For structural applications, material properties are crucial and engineers must take them into account.

Strength of Mild Steel vs Medium vs High-carbon Steel

In mechanics of materials, the strength of a material is its ability to withstand an applied load without failure or plastic deformation. Strength of materials basically considers the relationship between the external loads applied to a material and the resulting deformation or change in material dimensions. Strength of a material is its ability to withstand this applied load without failure or plastic deformation.

Ultimate Tensile Strength

Ultimate tensile strength of low-carbon steel is between 400 – 550 MPa.

Ultimate tensile strength of ultra-high-carbon steel is 1100 MPa.

The ultimate tensile strength is the maximum on the engineering stress-strain curve. This corresponds to the maximum stress that can be sustained by a structure in tension. Ultimate tensile strength is often shortened to “tensile strength” or even to “the ultimate.”  If this stress is applied and maintained, fracture will result. Often, this value is significantly more than the yield stress (as much as 50 to 60 percent more than the yield for some types of metals). When a ductile material reaches its ultimate strength, it experiences necking where the cross-sectional area reduces locally. The stress-strain curve contains no higher stress than the ultimate strength. Even though deformations can continue to increase, the stress usually decreases after the ultimate strength has been achieved. It is an intensive property; therefore its value does not depend on the size of the test specimen. However, it is dependent on other factors, such as the preparation of the specimen, the presence or otherwise of surface defects, and the temperature of the test environment and material. Ultimate tensile strengths vary from 50 MPa for an aluminum to as high as 3000 MPa for very high-strength steels.

Yield Strength

Yield strength of low-carbon steel is 250 MPa.

Yield strength of ultra-high-carbon steel is 800 MPa.

The yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning plastic behavior. Yield strength or yield stress is the material property defined as the stress at which a material begins to deform plastically whereas yield point is the point where nonlinear (elastic + plastic) deformation begins. Prior to the yield point, the material will deform elastically and will return to its original shape when the applied stress is removed. Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible. Some steels and other materials exhibit a behaviour termed a yield point phenomenon. Yield strengths vary from 35 MPa for a low-strength aluminum to greater than 1400 MPa for very high-strength steels.

Young’s Modulus of Elasticity

Young’s modulus of elasticity of low-carbon steel is 200 GPa.

The Young’s modulus of elasticity is the elastic modulus for tensile and compressive stress in the linear elasticity regime of a uniaxial deformation and is usually assessed by tensile tests. Up to a limiting stress, a body will be able to recover its dimensions on removal of the load. The applied stresses cause the atoms in a crystal to move from their equilibrium position. All the atoms are displaced the same amount and still maintain their relative geometry. When the stresses are removed, all the atoms return to their original positions and no permanent deformation occurs. According to the Hooke’s law, the stress is proportional to the strain (in the elastic region), and the slope is Young’s modulus. Young’s modulus is equal to the longitudinal stress divided by the strain.

Hardness of Mild Steel vs Medium vs High-carbon Steel

Brinell hardness of low-carbon steel is approximately 120 MPa.

Brinell hardness of high-carbon steel is approximately 200 MPa.

Rockwell hardness test is one of the most common indentation hardness tests, that has been developed for hardness testing. In contrast to Brinell test, the Rockwell tester measures the depth of penetration of an indenter under a large load (major load) compared to the penetration made by a preload (minor load). The minor load establishes the zero position. The major load is applied, then removed while still maintaining the minor load. The difference between depth of penetration before and after application of the major load is used to calculate the Rockwell hardness number. That is, the penetration depth and hardness are inversely proportional. The chief advantage of Rockwell hardness is its ability to display hardness values directly. The result is a dimensionless number noted as HRA, HRB, HRC, etc., where the last letter is the respective Rockwell scale.

The Rockwell C test is performed with a Brale penetrator (120°diamond cone) and a major load of 150kg.

Thermal Properties of Mild Steel vs Medium vs High-carbon Steel

Thermal properties of materials refer to the response of materials to changes in their thermodynamics/thermodynamic-properties/what-is-temperature-physics/”>temperature and to the application of heat. As a solid absorbs thermodynamics/what-is-energy-physics/”>energy in the form of heat, its temperature rises and its dimensions increase. But different materials react to the application of heat differently.

Heat capacity, thermal expansion, and thermal conductivity are properties that are often critical in the practical use of solids.

Melting Point of Mild Steel vs Medium vs High-carbon Steel

Melting point of low-carbon steel is around 1450°C.

In general, melting is a phase change of a substance from the solid to the liquid phase. The melting point of a substance is the temperature at which this phase change occurs. The melting point also defines a condition in which the solid and liquid can exist in equilibrium.

Thermal Conductivity of Mild Steel vs Medium vs High-carbon Steel

The thermal conductivity of typical steel is 20 W/(m.K).

The heat transfer characteristics of a solid material are measured by a property called the thermal conductivity, k (or λ), measured in W/m.K. It is a measure of a substance’s ability to transfer heat through a material by conduction. Note that Fourier’s law applies for all matter, regardless of its state (solid, liquid, or gas), therefore, it is also defined for liquids and gases.

The thermal conductivity of most liquids and solids varies with temperature. For vapors, it also depends upon pressure. In general:

Most materials are very nearly homogeneous, therefore we can usually write k = k (T). Similar definitions are associated with thermal conductivities in the y- and z-directions (ky, kz), but for an isotropic material the thermal conductivity is independent of the direction of transfer, kx = ky = kz = k.

See above:
Alloys

Carbon Steel

Carbon steels are iron–carbon alloys that may contain appreciable concentrations of other alloying elements. Plain carbon steels are iron-carbon alloys in which the properties are primarily derived from the presence of carbon. Some incidental elements like manganese, silicon, sulphur and phosphorus are present in small amounts due to the method of making steels and, not to modify the mechanical properties. Adding a small amount of non-metallic carbon to iron trades its great ductility for the greater strength. Due to its very-high strength, but still substantial toughness, and its ability to be greatly altered by heat treatment, steel is one of the most useful and common ferrous alloy in modern use. There are thousands of alloys that have different compositions and/or heat treatments. The mechanical properties are sensitive to the content of carbon, which is normally less than 1.0 wt%. According ot AISI classification, carbon steel is broken down into four classes based on carbon content:

• Low-carbon Steels. Low-carbon steel, also known as mild steel is now the most common form of steel because its price is relatively low while it provides material properties that are acceptable for many applications. Low-carbon steel contains approximately 0.05–0.25% carbon making it malleable and ductile. Mild steel has a relatively low tensile strength, but it is cheap and easy to form; surface hardness can be increased through carburizing.
• Medium-carbon Steels. Medium-carbon steel has approximately 0.3–0.6% carbon content. Balances ductility and strength and has good wear resistance. This grade of steel is mostly used in the production of machine components, shafts, axles, gears, crankshafts, coupling and forgings and could also be used in rails and railway wheels.
• High-carbon Steels. High-carbon steel has approximately 0.60 to 1.00% carbon content. Hardness is higher than the other grades but ductility decreases. High carbon steels could be used for springs, rope wires, hammers, screwdrivers, and wrenches.
• Ultra-high-carbon Steel. Ultra-high-carbon steel has approximately 1.25–2.0% carbon content. Steels that can be tempered to great hardness. This grade of steel could be used for hard steel products, such as truck springs, metal cutting tools and other special purposes like (non-industrial-purpose) knives, axles or punches. Most steels with more than 2.5% carbon content are made using powder metallurgy.

Alloy Steels

Steel is an alloy of iron and carbon, but the term alloy steel usually only refers to steels that contain other elements— like vanadium, molybdenum, or cobalt—in amounts sufficient to alter the properties of the base steel. In general, alloy steel is steel that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties. Stainless steels are specific group of high-alloy steels, that contain a minimum of 11% chromium content by mass and a maximum of 1.2% carbon by mass. Alloy steels are broken down into two groups:

• Low-alloy Steels. Low-alloy steels constitute a category of ferrous materials that exhibit mechanical properties superior to plain carbon steels resulting from additions of such alloying elements as nickel, chromium, and molybdenum, manganese, and silicon. The role of the alloying elements is to increase hardenability in order to optimize mechanical properties and toughness after heat treatment. In some cases, however, alloy additions are used to reduce environmental degradation under certain specified service conditions.
• High-alloy Steels. Steels with alloying greater than 5 wt% are typically classified as high-alloy steel. Stainless steels are the major types of high-alloy steels, but two other types are ultrahigh-strength nickel-cobalt steels and maraging steels. Stainless steels are defined as low-carbon high-alloy steels with at least 10.5% chromium with or without other alloying elements.

41xx steel – Chromoly Steel – Medium-carbon Ultrahigh-strength Steels

Chromoly steel is medium-carbon ultrahigh-strength low alloy steel that gets its name from a combination of the words “chromium” and “molybdenum” – two of the major alloying elements. Chromoly steel is often used when more strength is required than that of mild carbon steel, though it often comes at an increase in cost. Chromoly falls under the AISI 41xx steel designations (ASTM A519). Examples of applications for 4130, 4140 and 4145 include structural tubing, bicycle frames, crank shafts, chain links, drill collars, gas bottles for transportation of pressurized gases, firearm parts, clutch and flywheel components, and roll cages.

Properties of Carbon Steel vs Alloy Steel

Material properties are intensive properties, that means they are independent of the amount of mass and may vary from place to place within the system at any moment. The basis of materials science involves studying the structure of materials, and relating them to their properties (mechanical, electrical etc.). Once a materials scientist knows about this structure-property correlation, they can then go on to study the relative performance of a material in a given application. The major determinants of the structure of a material and thus of its properties are its constituent chemical elements and the way in which it has been processed into its final form.

Density of Carbon Steel vs Alloy Steel

Density of typical steel is 8.05 g/cm³.

Density of typical alloy steel is 7.85 g/cm³. (4150 Chromoly)

Density is defined as the mass per unit volume. It is an intensive property, which is mathematically defined as mass divided by volume:

ρ = m/V

In words, the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance. The standard SI unit is kilograms per cubic meter (kg/m³). The Standard English unit is pounds mass per cubic foot (lbm/ft³).

Since the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance, it is obvious, the density of a substance strongly depends on its atomic mass and also on the atomic number density (N; atoms/cm³),

• Atomic Weight. The atomic mass is carried by the atomic nucleus, which occupies only about 10^-12 of the total volume of the atom or less, but it contains all the positive charge and at least 99.95% of the total mass of the atom. Therefore it is determined by the mass number (number of protons and neutrons).
• Atomic Number Density. The atomic number density (N; atoms/cm³), which is associated with atomic radii, is the number of atoms of a given type per unit volume (V; cm³) of the material. The atomic number density (N; atoms/cm³) of a pure material having atomic or molecular weight (M; grams/mol) and the material density (⍴; gram/cm³) is easily computed from the following equation using Avogadro’s number (N_A = 6.022×10²³ atoms or molecules per mole):
• Crystal Structure. Density of crystalline substance is significantly affected by its crystal structure. FCC structure, along with its hexagonal relative (hcp), has the most efficient packing factor (74%). Metals containing FCC structures include austenite, aluminum, copper, lead, silver, gold, nickel, platinum, and thorium.

Mechanical Properties of Carbon Steel vs Alloy Steel

Materials are frequently chosen for various applications because they have desirable combinations of mechanical characteristics. For structural applications, material properties are crucial and engineers must take them into account.

Strength of Carbon Steel vs Alloy Steel

In mechanics of materials, the strength of a material is its ability to withstand an applied load without failure or plastic deformation. Strength of materials basically considers the relationship between the external loads applied to a material and the resulting deformation or change in material dimensions. Strength of a material is its ability to withstand this applied load without failure or plastic deformation.

Ultimate Tensile Strength

Ultimate tensile strength of low-carbon steel is between 400 – 550 MPa.

Ultimate tensile strength of ultra-high-carbon steel is 1100 MPa.

Ultimate tensile strength of 41xx steel – chromoly steel depends on certain grade, but it is about 700 MPa.

The ultimate tensile strength is the maximum on the engineering stress-strain curve. This corresponds to the maximum stress that can be sustained by a structure in tension. Ultimate tensile strength is often shortened to “tensile strength” or even to “the ultimate.”  If this stress is applied and maintained, fracture will result. Often, this value is significantly more than the yield stress (as much as 50 to 60 percent more than the yield for some types of metals). When a ductile material reaches its ultimate strength, it experiences necking where the cross-sectional area reduces locally. The stress-strain curve contains no higher stress than the ultimate strength. Even though deformations can continue to increase, the stress usually decreases after the ultimate strength has been achieved. It is an intensive property; therefore its value does not depend on the size of the test specimen. However, it is dependent on other factors, such as the preparation of the specimen, the presence or otherwise of surface defects, and the temperature of the test environment and material. Ultimate tensile strengths vary from 50 MPa for an aluminum to as high as 3000 MPa for very high-strength steels.

Yield Strength

Yield strength of low-carbon steel is 250 MPa.

Yield strength of ultra-high-carbon steel is 800 MPa.

Yield strength of 41xx steel – chromoly steel depends on certain grade, but it is about 500 MPa.

The yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning plastic behavior. Yield strength or yield stress is the material property defined as the stress at which a material begins to deform plastically whereas yield point is the point where nonlinear (elastic + plastic) deformation begins. Prior to the yield point, the material will deform elastically and will return to its original shape when the applied stress is removed. Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible. Some steels and other materials exhibit a behaviour termed a yield point phenomenon. Yield strengths vary from 35 MPa for a low-strength aluminum to greater than 1400 MPa for very high-strength steels.

Young’s Modulus of Elasticity

Young’s modulus of elasticity of low-carbon steel is 200 GPa.

Young’s modulus of elasticity 41xx steel – chromoly steel is 205 GPa.

The Young’s modulus of elasticity is the elastic modulus for tensile and compressive stress in the linear elasticity regime of a uniaxial deformation and is usually assessed by tensile tests. Up to a limiting stress, a body will be able to recover its dimensions on removal of the load. The applied stresses cause the atoms in a crystal to move from their equilibrium position. All the atoms are displaced the same amount and still maintain their relative geometry. When the stresses are removed, all the atoms return to their original positions and no permanent deformation occurs. According to the Hooke’s law, the stress is proportional to the strain (in the elastic region), and the slope is Young’s modulus. Young’s modulus is equal to the longitudinal stress divided by the strain.

Hardness of Carbon Steel vs Alloy Steel

Brinell hardness of low-carbon steel is approximately 120 MPa.

Brinell hardness of high-carbon steel is approximately 200 MPa.

Brinell hardness of 41xx steel – chromoly steel is approximately 200 MPa.

Rockwell hardness test is one of the most common indentation hardness tests, that has been developed for hardness testing. In contrast to Brinell test, the Rockwell tester measures the depth of penetration of an indenter under a large load (major load) compared to the penetration made by a preload (minor load). The minor load establishes the zero position. The major load is applied, then removed while still maintaining the minor load. The difference between depth of penetration before and after application of the major load is used to calculate the Rockwell hardness number. That is, the penetration depth and hardness are inversely proportional. The chief advantage of Rockwell hardness is its ability to display hardness values directly. The result is a dimensionless number noted as HRA, HRB, HRC, etc., where the last letter is the respective Rockwell scale.

The Rockwell C test is performed with a Brale penetrator (120°diamond cone) and a major load of 150kg.

Thermal Properties of Carbon Steel vs Alloy Steel

Thermal properties of materials refer to the response of materials to changes in their thermodynamics/thermodynamic-properties/what-is-temperature-physics/”>temperature and to the application of heat. As a solid absorbs thermodynamics/what-is-energy-physics/”>energy in the form of heat, its temperature rises and its dimensions increase. But different materials react to the application of heat differently.

Heat capacity, thermal expansion, and thermal conductivity are properties that are often critical in the practical use of solids.

Melting Point of Carbon Steel vs Alloy Steel

Melting point of low-carbon steel is around 1450°C.

Melting point of 41xx steel – chromoly steel is around 1427°C.

In general, melting is a phase change of a substance from the solid to the liquid phase. The melting point of a substance is the temperature at which this phase change occurs. The melting point also defines a condition in which the solid and liquid can exist in equilibrium.

Thermal Conductivity of Carbon Steel vs Alloy Steel

The thermal conductivity of typical steel is 20 W/(m.K).

The thermal conductivity of 41xx steel – chromoly steel is around 41 W/(m.K).

The heat transfer characteristics of a solid material are measured by a property called the thermal conductivity, k (or λ), measured in W/m.K. It is a measure of a substance’s ability to transfer heat through a material by conduction. Note that Fourier’s law applies for all matter, regardless of its state (solid, liquid, or gas), therefore, it is also defined for liquids and gases.

The thermal conductivity of most liquids and solids varies with temperature. For vapors, it also depends upon pressure. In general:

Most materials are very nearly homogeneous, therefore we can usually write k = k (T). Similar definitions are associated with thermal conductivities in the y- and z-directions (ky, kz), but for an isotropic material the thermal conductivity is independent of the direction of transfer, kx = ky = kz = k.

See above:
Alloys

As can be seen from figure, the percentage of carbon present and the temperature define the phase of the iron carbon alloy and therefore its physical characteristics and mechanical properties. The percentage of carbon determines the type of the ferrous alloy: iron, carbon steel or cast iron.

Carbon Steel

Carbon steels are iron–carbon alloys that may contain appreciable concentrations of other alloying elements. Plain carbon steels are iron-carbon alloys in which the properties are primarily derived from the presence of carbon. Some incidental elements like manganese, silicon, sulphur and phosphorus are present in small amounts due to the method of making steels and, not to modify the mechanical properties. Adding a small amount of non-metallic carbon to iron trades its great ductility for the greater strength. Due to its very-high strength, but still substantial toughness, and its ability to be greatly altered by heat treatment, steel is one of the most useful and common ferrous alloy in modern use. There are thousands of alloys that have different compositions and/or heat treatments. The mechanical properties are sensitive to the content of carbon, which is normally less than 1.0 wt%. According ot AISI classification, carbon steel is broken down into four classes based on carbon content:

• Low-carbon Steels. Low-carbon steel, also known as mild steel is now the most common form of steel because its price is relatively low while it provides material properties that are acceptable for many applications. Low-carbon steel contains approximately 0.05–0.25% carbon making it malleable and ductile. Mild steel has a relatively low tensile strength, but it is cheap and easy to form; surface hardness can be increased through carburizing.
• Medium-carbon Steels. Medium-carbon steel has approximately 0.3–0.6% carbon content. Balances ductility and strength and has good wear resistance. This grade of steel is mostly used in the production of machine components, shafts, axles, gears, crankshafts, coupling and forgings and could also be used in rails and railway wheels.
• High-carbon Steels. High-carbon steel has approximately 0.60 to 1.00% carbon content. Hardness is higher than the other grades but ductility decreases. High carbon steels could be used for springs, rope wires, hammers, screwdrivers, and wrenches.
• Ultra-high-carbon Steel. Ultra-high-carbon steel has approximately 1.25–2.0% carbon content. Steels that can be tempered to great hardness. This grade of steel could be used for hard steel products, such as truck springs, metal cutting tools and other special purposes like (non-industrial-purpose) knives, axles or punches. Most steels with more than 2.5% carbon content are made using powder metallurgy.

Cast Irons

In materials engineering, cast irons are a class of ferrous alloys with carbon contents above 2.14 wt%. Typically, cast irons contain from 2.14 wt% to 4.0 wt% carbon and anywhere from 0.5 wt% to 3 wt% of silicon. Iron alloys with lower carbon content are known as steel. The difference is that cast irons can take advantage of eutectic solidification in the binary iron-carbon system. The term eutectic is Greek for “easy or well melting,” and the eutectic point represents the composition on the phase diagram where the lowest melting temperature is achieved. For the iron-carbon system the eutectic point occurs at a composition of 4.26 wt% C and a temperature of 1148°C.

Cast iron, therefore, has a lower melting point (between approximately 1150°C and 1300°C) than traditional steel, which makes it easier to cast than standard steels. Because of its high fluidity when molten, the liquid iron easily fills intricate molds and can form complex shapes. Most applications require very little finishing, so cast irons are used for a wide variety of small parts as well as large ones. It is an ideal material for sand casting into complex shapes such as exhaust manifolds without the need for extensive further machining. Furthermore, some cast irons are very brittle, and casting is the most convenient fabrication technique. Cast irons have become an engineering material with a wide range of applications and are used in pipes, machines and automotive industry parts, such as cylinder heads, cylinder blocks and gearbox cases. It is resistant to damage by oxidation.

Types of Cast Irons

Cast irons also comprise a large family of different types of iron, depending on how the carbon-rich phase forms during solidification. The microstructure of cast irons can be controlled to provide products that have excellent ductility, good machinability, excellent vibration damping, superb wear resistance, and good thermal conductivity. With proper alloying, the corrosion resistance of cast irons can equal that of stainless steels and nickel-base alloys in many services. For most cast irons, the carbon exists as graphite, and both microstructure and mechanical behavior depend on composition and heat treatment. The most common cast iron types are:

• Gray cast iron. Gray cast iron is the oldest and most common type of cast iron. Gray cast iron is characterised by its graphitic microstructure, which causes fractures of the material to have a gray appearance. This is due to the presence of graphite in its composition. In gray cast iron the graphite forms as flakes, taking on a three dimensional geometry.
• White cast iron. White cast irons are hard, brittle, and unmachinable, while gray irons with softer graphite are reasonably strong and machinable. A fracture surface of this alloy has a white appearance, and thus it is termed white cast iron.
• Malleable cast iron. Malleable cast iron is white cast iron that has been annealed. Through an annealing heat treatment, the brittle structure as first cast is transformed into the malleable form. Therefore, its composition is very similar to that of white cast iron, with slightly higher amounts of carbon and silicon.
• Ductile cast iron. Ductile iron, also known as nodular iron, is very similar to gray iron in composition, but during solidification the graphite nucleates as spherical particles (nodules) in ductile iron, rather than as flakes. Ductile iron is stronger and more shock resistant than gray iron. In fact, ductile iron has mechanical characteristics approaching those of steel, while it retains high fluidity when molten and lower melting point.

Properties of Carbon Steel vs Cast Iron

Material properties are intensive properties, that means they are independent of the amount of mass and may vary from place to place within the system at any moment. The basis of materials science involves studying the structure of materials, and relating them to their properties (mechanical, electrical etc.). Once a materials scientist knows about this structure-property correlation, they can then go on to study the relative performance of a material in a given application. The major determinants of the structure of a material and thus of its properties are its constituent chemical elements and the way in which it has been processed into its final form.

Density of Carbon Steel vs Cast Iron

Density of typical steel is 8.05 g/cm³.

Density of typical cast iron is 7.03 g/cm³.

Density is defined as the mass per unit volume. It is an intensive property, which is mathematically defined as mass divided by volume:

ρ = m/V

In words, the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance. The standard SI unit is kilograms per cubic meter (kg/m³). The Standard English unit is pounds mass per cubic foot (lbm/ft³).

Since the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance, it is obvious, the density of a substance strongly depends on its atomic mass and also on the atomic number density (N; atoms/cm³),

• Atomic Weight. The atomic mass is carried by the atomic nucleus, which occupies only about 10^-12 of the total volume of the atom or less, but it contains all the positive charge and at least 99.95% of the total mass of the atom. Therefore it is determined by the mass number (number of protons and neutrons).
• Atomic Number Density. The atomic number density (N; atoms/cm³), which is associated with atomic radii, is the number of atoms of a given type per unit volume (V; cm³) of the material. The atomic number density (N; atoms/cm³) of a pure material having atomic or molecular weight (M; grams/mol) and the material density (⍴; gram/cm³) is easily computed from the following equation using Avogadro’s number (N_A = 6.022×10²³ atoms or molecules per mole):
• Crystal Structure. Density of crystalline substance is significantly affected by its crystal structure. FCC structure, along with its hexagonal relative (hcp), has the most efficient packing factor (74%). Metals containing FCC structures include austenite, aluminum, copper, lead, silver, gold, nickel, platinum, and thorium.

Mechanical Properties of Carbon Steel vs Cast Iron

Materials are frequently chosen for various applications because they have desirable combinations of mechanical characteristics. For structural applications, material properties are crucial and engineers must take them into account.

Strength of Carbon Steel vs Cast Iron

In mechanics of materials, the strength of a material is its ability to withstand an applied load without failure or plastic deformation. Strength of materials basically considers the relationship between the external loads applied to a material and the resulting deformation or change in material dimensions. Strength of a material is its ability to withstand this applied load without failure or plastic deformation.

Ultimate Tensile Strength

Ultimate tensile strength of low-carbon steel is between 400 – 550 MPa.

Ultimate tensile strength of ultra-high-carbon steel is 1100 MPa.

Ultimate tensile strength of gray cast iron (ASTM A48 Class 40) is 295 MPa.

Ultimate tensile strength of martensitic white cast iron (ASTM A532 Class 1 Type A) is 350 MPa.

Ultimate tensile strength of malleable cast iron – ASTM A220 is 580 MPa.

Ultimate tensile strength of ductile cast Iron – ASTM A536 – 60-40-18 is 414 Mpa (>60 ksi).

The ultimate tensile strength is the maximum on the engineering stress-strain curve. This corresponds to the maximum stress that can be sustained by a structure in tension. Ultimate tensile strength is often shortened to “tensile strength” or even to “the ultimate.”  If this stress is applied and maintained, fracture will result. Often, this value is significantly more than the yield stress (as much as 50 to 60 percent more than the yield for some types of metals). When a ductile material reaches its ultimate strength, it experiences necking where the cross-sectional area reduces locally. The stress-strain curve contains no higher stress than the ultimate strength. Even though deformations can continue to increase, the stress usually decreases after the ultimate strength has been achieved. It is an intensive property; therefore its value does not depend on the size of the test specimen. However, it is dependent on other factors, such as the preparation of the specimen, the presence or otherwise of surface defects, and the temperature of the test environment and material. Ultimate tensile strengths vary from 50 MPa for an aluminum to as high as 3000 MPa for very high-strength steels.

Yield Strength

Yield strength of low-carbon steel is 250 MPa.

Yield strength of ultra-high-carbon steel is 800 MPa.

The yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning plastic behavior. Yield strength or yield stress is the material property defined as the stress at which a material begins to deform plastically whereas yield point is the point where nonlinear (elastic + plastic) deformation begins. Prior to the yield point, the material will deform elastically and will return to its original shape when the applied stress is removed. Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible. Some steels and other materials exhibit a behaviour termed a yield point phenomenon. Yield strengths vary from 35 MPa for a low-strength aluminum to greater than 1400 MPa for very high-strength steels.

Young’s Modulus of Elasticity

Young’s modulus of elasticity of low-carbon steel is 200 GPa.

Young’s modulus of elasticity of gray cast iron (ASTM A48 Class 40) is 124 GPa.

Young’s modulus of elasticity of martensitic white cast iron (ASTM A532 Class 1 Type A) is 175 GPa.

Young’s modulus of elasticity of malleable cast iron – ASTM A220 is 172 GPa.

Young’s modulus of elasticity ductile cast Iron – ASTM A536 – 60-40-18 is 170 GPa.

The Young’s modulus of elasticity is the elastic modulus for tensile and compressive stress in the linear elasticity regime of a uniaxial deformation and is usually assessed by tensile tests. Up to a limiting stress, a body will be able to recover its dimensions on removal of the load. The applied stresses cause the atoms in a crystal to move from their equilibrium position. All the atoms are displaced the same amount and still maintain their relative geometry. When the stresses are removed, all the atoms return to their original positions and no permanent deformation occurs. According to the Hooke’s law, the stress is proportional to the strain (in the elastic region), and the slope is Young’s modulus. Young’s modulus is equal to the longitudinal stress divided by the strain.

Hardness of Carbon Steel vs Cast Iron

Brinell hardness of low-carbon steel is approximately 120 MPa.

Brinell hardness of high-carbon steel is approximately 200 MPa.

Brinell hardness of gray cast iron (ASTM A48 Class 40) is approximately 235 MPa.

Brinell hardness of gray cast iron martensitic white cast iron (ASTM A532 Class 1 Type A) is approximately 600 MPa.

Brinell hardness of malleable cast iron – ASTM A220 is approximately 250 MPa.

Brinell hardness of ductile cast Iron – ASTM A536 – 60-40-18 is approximately 150 – 180 MPa.

Rockwell hardness test is one of the most common indentation hardness tests, that has been developed for hardness testing. In contrast to Brinell test, the Rockwell tester measures the depth of penetration of an indenter under a large load (major load) compared to the penetration made by a preload (minor load). The minor load establishes the zero position. The major load is applied, then removed while still maintaining the minor load. The difference between depth of penetration before and after application of the major load is used to calculate the Rockwell hardness number. That is, the penetration depth and hardness are inversely proportional. The chief advantage of Rockwell hardness is its ability to display hardness values directly. The result is a dimensionless number noted as HRA, HRB, HRC, etc., where the last letter is the respective Rockwell scale.

The Rockwell C test is performed with a Brale penetrator (120°diamond cone) and a major load of 150kg.

Thermal Properties of Carbon Steel vs Cast Iron

Thermal properties of materials refer to the response of materials to changes in their thermodynamics/thermodynamic-properties/what-is-temperature-physics/”>temperature and to the application of heat. As a solid absorbs thermodynamics/what-is-energy-physics/”>energy in the form of heat, its temperature rises and its dimensions increase. But different materials react to the application of heat differently.

Heat capacity, thermal expansion, and thermal conductivity are properties that are often critical in the practical use of solids.

Melting Point of Carbon Steel vs Cast Iron

Melting point of low-carbon steel is around 1450°C.

Melting point of gray cast iron – ASTM A48 steel is around 1260°C.

Melting point of martensitic white cast iron (ASTM A532 Class 1 Type A) is around 1260°C.

Melting point of malleable cast iron – ASTM A220 is around 1260°C.

Melting point of ductile cast Iron – ASTM A536 – 60-40-18 steel is around 1150°C.

In general, melting is a phase change of a substance from the solid to the liquid phase. The melting point of a substance is the temperature at which this phase change occurs. The melting point also defines a condition in which the solid and liquid can exist in equilibrium.

Thermal Conductivity of Carbon Steel vs Cast Iron

The thermal conductivity of typical steel is 20 W/(m.K).

The thermal conductivity of gray cast iron – ASTM A48 is 53 W/(m.K).

The thermal conductivity of martensitic white cast iron (ASTM A532 Class 1 Type A) is 15 – 30 W/(m.K).

The thermal conductivity of malleable cast iron is approximately 40 W/(m.K).

The thermal conductivity of ductile cast iron is 36 W/(m.K).

The heat transfer characteristics of a solid material are measured by a property called the thermal conductivity, k (or λ), measured in W/m.K. It is a measure of a substance’s ability to transfer heat through a material by conduction. Note that Fourier’s law applies for all matter, regardless of its state (solid, liquid, or gas), therefore, it is also defined for liquids and gases.

The thermal conductivity of most liquids and solids varies with temperature. For vapors, it also depends upon pressure. In general:

Most materials are very nearly homogeneous, therefore we can usually write k = k (T). Similar definitions are associated with thermal conductivities in the y- and z-directions (ky, kz), but for an isotropic material the thermal conductivity is independent of the direction of transfer, kx = ky = kz = k.

See above:
Alloys

Low-melting-point metals and alloys are somehow in opposition to refractory metals. Some low-melting-point alloys may be used as a solder, thus they are known as fusible alloys. A fusible alloy is a metal alloy capable of being easily fused, i.e. easily meltable, at relatively low temperatures.

Solder – Tin – Lead Eutectic Alloy

Soldering is a technique for joining metals using a filler metal alloy that has a melting temperature less than about 425°C (800°F). Because of this lower temperature and different alloys used as fillers, the metallurgical reaction between filler and work piece is minimal, resulting in a weaker joint. In electronics assembly, the eutectic alloy with 63% tin and 37% lead (or 60/40, which is almost identical in melting point) has been the alloy of choice. This eutectic alloy has melting point lower than those of either tin or lead.

Tin is an important constituent in solders because it wets and adheres to many common base metals at temperatures considerably below their melting points. Small amounts of various metals, notably antimony and silver, are added to tin-lead solders to increase their strength. 60-40 solder provides strong and reliable joints under a variety of environmental conditions. There are also high-tin solders, which are used for joining parts of electrical apparatuses because their electrical conductivity is higher than that of high-lead solders. These solders are also used where lead may be a hazard, for example, in contact with drinking water or food.

Lead Alloys

Lead is a heavy metal that is denser than most common materials. Lead is soft and malleable, and has a relatively low melting point. Lead is widely used as a gamma shield. Major advantage of lead shield is in its compactness due to its higher density. It has high corrosion resistance, malleability, unusual electrical properties, and the ability to form useful alloys. Representative uses include: shielding agent against x-ray and gamma radiation; diecast grids for batteries; coatings that prepare surfaces for soldering. On the other hand, lead is extremely toxic and poses certain environmental hazards.

Lead forms a wide range of low-melting alloys and readily alloys with tin in all proportions, forming the tin-lead solders used widely in industry. In nuclear industry, lead and lead-bismuth alloys can be used as a reactor coolant.

Lead and Lead-bismuth Eutectic

Lead, lead-bismuth eutectic, and other metals have also been proposed and occasionally used. The lead-cooled fast reactor is a nuclear reactor design that features a fast neutron spectrum and molten lead or lead-bismuth eutectic coolant. Lead-Bismuth Eutectic or LBE is a eutectic alloy of lead (44.5%) and bismuth (55.5%). Molten lead or lead-bismuth eutectic can be used as the primary coolant because lead and bismuth have low neutron absorption and relatively low melting points.

Melting and boiling points of lead and lead-bismuth eutectic mixture are:

• lead
  • melting point – 327.5°C
  • boiling point – 1749°C
• lead-bismuth – eutectic mixture
  • melting point – 123.5°C
  • boiling point – 1670°C

Zinc Alloys

Zinc is a brittle metal and has a relatively low melting point of 419 °C (787 °F), resists corrosion, is ductile and malleable, and is highly soluble in copper. Zinc and zinc alloys are used in the form of coatings, castings, rolled sheets, drawn wire, forgings, and extrusions. Other uses of zinc are as a major constituent in brassesm nickel-silver alloys, typewriter metal, soft and aluminium solder, and commercial bronze.

Alloys of zinc with small amounts of copper, aluminium, and magnesium are useful in die casting as well as spin casting, especially in the automotive, electrical, and hardware industries. Zinc alloys have low melting points, require relatively low heat input, do not require fluxing or protective atmospheres. Because of their high fluidity, zinc alloys can be cast in much thinner walls than other die castings alloys, and they can be die cast to tighter dimensional tolerances. These zinc alloys are marketed under the name Zamak. The name zamak is an acronym of the German names for the metals of which the alloys are composed: Zink (zinc), Aluminium, Magnesium and Kupfer (copper). The low melting point together with the low viscosity of the alloy makes possible the production of small and intricate shapes.

See above:
Alloys

Refractory metals and alloys are well known for their extraordinary resistance to heat and wear. Key requirement to withstand high temperatures is a high melting point and stable mechanical properties (e.g. high hardness) even at high temperatures.

The most common refractory metals include five elements: niobium and molybdenum of the fifth period and tantalum, tungsten, and rhenium of the sixth period. They all share some properties, including a melting point above 2000 °C and high hardness at room temperature.

Poor low-temperature fabricability and extreme oxidability at high temperatures are main disadvantages of most refractory metals. Application of these metals requires a protective atmosphere or coating.

The strength of refractory metals at high temperatures, in combination with their hardness, makes them ideal for cutting and drilling tools. Refractory metal-based alloys are used in virtually all major industries, including electronics, aerospace, automotive, chemicals, mining, nuclear technology and metal processing. Today usage is not limited to lamp filaments, electron tube grids and heating elements.

• Tungsten is an extremely dense metal and it has the highest melting point of all metals, at 3,410 °C. Moreover, tungsten is an excellent alloying agent. The major use of tungsten is in cemented carbide metal cutting tools and wear-resistant materials.Produces stable carbides and refines grain size so as to increase hardness, particularly at high temperatures. Tungsten is used extensively in high-speed tool steels and has been proposed as a substitute for molybdenum in reduced-activation ferritic steels for nuclear applications. The addition of about 10% of tungsten and molybdenum in total maximises efficiently the hardness and toughness of high speed steels and maintains those properties at the high temperatures generated when cutting metals. Tungsten and molybdenum  are  interchangeable  at  an  atomic  level  and  both  promote  resistance  to  tempering which   gives improved   tool   cutting   performance   at   higher   temperatures.
• Molybdenum increases hardenability and strength, particularly at high temperatures due to the high melting point of molybdenum. Molybdenum is unique in the extent to which it increases the high-temperature tensile and creep strengths of steel. It retards the transformation of austenite to pearlite far more than it does the transformation of austenite to bainite; thus, bainite may be produced by continuous cooling of molybdenum-containing steels. Most common molybdenum-based alloy is is the Titanium-Zirconium-Molybdenum alloy TZM, composed of 0.5% titanium and 0.08% of zirconium (with molybdenum being the rest). It is typically manufactured by powder metallurgy or arc-casting processes. The alloy exhibits a higher creep resistance and strength at high temperatures, making service temperatures of above 1060 °C possible for the material.

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Alloys

Corrosion-resistant alloys, as their name indicates, are alloys with enhanced corrosion resistance. Some ferrous and many non-ferrous metals and alloys are widely used in corrosive environments. In all cases, it strongly depends on certain environment and other conditions. Corrosion-resistant alloys are used for water piping and many chemical and industrial applications. In case of ferrous alloys, we are talking about stainless steels and to some extent about cast irons. But some non-ferrous corrosion-resistant alloys exhibit remarkable corrosion resistance nad therefore they may be used for many special purposes. There are two main reasons why nonferrous materials are preferred over steels and stainless steels for many of these applications. For example, many of the non-ferrous metals and alloys possess much higher resistance to corrosion than available alloy steels and stainless steel grades. Second, a high strength-to-weight ratio or high thermal and electrical conductivity may provide a distinct advantage over a ferrous alloy.

Thermal Properties of Corrosion-resistant Alloys

Thermal properties of materials refer to the response of materials to changes in their thermodynamics/thermodynamic-properties/what-is-temperature-physics/”>temperature and to the application of heat. As a solid absorbs thermodynamics/what-is-energy-physics/”>energy in the form of heat, its temperature rises and its dimensions increase. But different materials react to the application of heat differently.

Heat capacity, thermal expansion, and thermal conductivity are properties that are often critical in the practical use of solids.

Melting Point of Corrosion-resistant Alloys

Melting point of aluminium bronze – UNS C95400 is around 1030°C.

Melting point of superalloy – Inconel 718 steel is around 1400°C.

Melting point of commercially pure titanium – Grade 2 is around 1660°C.

Melting point of 6061 aluminium alloy is around 600°C.

Melting point of stainless steel – type 304 steel is around 1450°C.

In general, melting is a phase change of a substance from the solid to the liquid phase. The melting point of a substance is the temperature at which this phase change occurs. The melting point also defines a condition in which the solid and liquid can exist in equilibrium.

Thermal Conductivity of Corrosion-resistant Alloys

The thermal conductivity of aluminium bronze – UNS C95400 is 59 W/(m.K).

The thermal conductivity of superalloy – Inconel 718 is 6.5 W/(m.K).

The thermal conductivity of commercially pure titanium – Grade 2 is 16 W/(m.K).

The thermal conductivity of 6061 aluminium alloy is 150 W/(m.K).

The thermal conductivity of stainless steel – type 304 is 20 W/(m.K).

The heat transfer characteristics of a solid material are measured by a property called the thermal conductivity, k (or λ), measured in W/m.K. It is a measure of a substance’s ability to transfer heat through a material by conduction. Note that Fourier’s law applies for all matter, regardless of its state (solid, liquid, or gas), therefore, it is also defined for liquids and gases.

The thermal conductivity of most liquids and solids varies with temperature. For vapors, it also depends upon pressure. In general:

Most materials are very nearly homogeneous, therefore we can usually write k = k (T). Similar definitions are associated with thermal conductivities in the y- and z-directions (ky, kz), but for an isotropic material the thermal conductivity is independent of the direction of transfer, kx = ky = kz = k.

See above:
Corrosion-resistant Alloys

Corrosion-resistant alloys, as their name indicates, are alloys with enhanced corrosion resistance. Some ferrous and many non-ferrous metals and alloys are widely used in corrosive environments. In all cases, it strongly depends on certain environment and other conditions. Corrosion-resistant alloys are used for water piping and many chemical and industrial applications. In case of ferrous alloys, we are talking about stainless steels and to some extent about cast irons. But some non-ferrous corrosion-resistant alloys exhibit remarkable corrosion resistance nad therefore they may be used for many special purposes. There are two main reasons why nonferrous materials are preferred over steels and stainless steels for many of these applications. For example, many of the non-ferrous metals and alloys possess much higher resistance to corrosion than available alloy steels and stainless steel grades. Second, a high strength-to-weight ratio or high thermal and electrical conductivity may provide a distinct advantage over a ferrous alloy.

Strength of Corrosion-resistant Alloys

In mechanics of materials, the strength of a material is its ability to withstand an applied load without failure or plastic deformation. Strength of materials basically considers the relationship between the external loads applied to a material and the resulting deformation or change in material dimensions. Strength of a material is its ability to withstand this applied load without failure or plastic deformation.

Ultimate Tensile Strength

Ultimate tensile strength of aluminium bronze – UNS C95400 is about 550 MPa.

Ultimate tensile strength of superalloy – Inconel 718 depends on heat treatment process, but it is about 1200 MPa.

Ultimate tensile strength of commercially pure titanium – Grade 2 is about 340 MPa.

Ultimate tensile strength of 6061 aluminium alloy depends greatly on the temper of the material, but for T6 temper it is about 290 MPa.

Ultimate tensile strength of stainless steel – type 304 is 515 MPa.

The ultimate tensile strength is the maximum on the engineering stress-strain curve. This corresponds to the maximum stress that can be sustained by a structure in tension. Ultimate tensile strength is often shortened to “tensile strength” or even to “the ultimate.”  If this stress is applied and maintained, fracture will result. Often, this value is significantly more than the yield stress (as much as 50 to 60 percent more than the yield for some types of metals). When a ductile material reaches its ultimate strength, it experiences necking where the cross-sectional area reduces locally. The stress-strain curve contains no higher stress than the ultimate strength. Even though deformations can continue to increase, the stress usually decreases after the ultimate strength has been achieved. It is an intensive property; therefore its value does not depend on the size of the test specimen. However, it is dependent on other factors, such as the preparation of the specimen, the presence or otherwise of surface defects, and the temperature of the test environment and material. Ultimate tensile strengths vary from 50 MPa for an aluminum to as high as 3000 MPa for very high-strength steels.

Yield Strength

Yield strength of aluminium bronze – UNS C95400 is about 250 MPa.

Yield strength of superalloy – Inconel 718 depends on heat treatment process, but it is about 1030 MPa.

Yield strength of commercially pure titanium – Grade 2 is about 300 MPa.

Yield strength of 6061 aluminium alloy depends greatly on the temper of the material, but for T6 temper it is about 240 MPa.

Yield strength of stainless steel – type 304 is  205 MPa.

The yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning plastic behavior. Yield strength or yield stress is the material property defined as the stress at which a material begins to deform plastically whereas yield point is the point where nonlinear (elastic + plastic) deformation begins. Prior to the yield point, the material will deform elastically and will return to its original shape when the applied stress is removed. Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible. Some steels and other materials exhibit a behaviour termed a yield point phenomenon. Yield strengths vary from 35 MPa for a low-strength aluminum to greater than 1400 MPa for very high-strength steels.

Young’s Modulus of Elasticity

Young’s modulus of elasticity of aluminium bronze – UNS C95400 is about 110 GPa.

Young’s modulus of elasticity of superalloy – Inconel 718 is 200 GPa.

Young’s modulus of elasticity of commercially pure titanium – Grade 2 is about 105 GPa.

Young’s modulus of elasticity of 6061 aluminium alloy is about 69 GPa.

Young’s modulus of elasticity stainless steel – type 304 and 304L is 193 GPa.

The Young’s modulus of elasticity is the elastic modulus for tensile and compressive stress in the linear elasticity regime of a uniaxial deformation and is usually assessed by tensile tests. Up to a limiting stress, a body will be able to recover its dimensions on removal of the load. The applied stresses cause the atoms in a crystal to move from their equilibrium position. All the atoms are displaced the same amount and still maintain their relative geometry. When the stresses are removed, all the atoms return to their original positions and no permanent deformation occurs. According to the Hooke’s law, the stress is proportional to the strain (in the elastic region), and the slope is Young’s modulus. Young’s modulus is equal to the longitudinal stress divided by the strain.

Hardness of Corrosion-resistant Alloys

Brinell hardness of aluminium bronze – UNS C95400 is approximately 170 MPa.

Brinell hardness of superalloy – Inconel 718 depends on heat treatment process, but it is approximately 330 MPa.

Rockwell hardness of commercially pure titanium – Grade 2 is approximately 80 HRB.

Brinell hardness of 6061 aluminium alloy depends greatly on the temper of the material, but for T6 temper it is approximately 95 MPa.

Brinell hardness of stainless steel – type 304 is approximately 201 MPa.

Rockwell hardness test is one of the most common indentation hardness tests, that has been developed for hardness testing. In contrast to Brinell test, the Rockwell tester measures the depth of penetration of an indenter under a large load (major load) compared to the penetration made by a preload (minor load). The minor load establishes the zero position. The major load is applied, then removed while still maintaining the minor load. The difference between depth of penetration before and after application of the major load is used to calculate the Rockwell hardness number. That is, the penetration depth and hardness are inversely proportional. The chief advantage of Rockwell hardness is its ability to display hardness values directly. The result is a dimensionless number noted as HRA, HRB, HRC, etc., where the last letter is the respective Rockwell scale.

The Rockwell C test is performed with a Brale penetrator (120°diamond cone) and a major load of 150kg.

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See above:
Corrosion-resistant Alloys

Corrosion-resistant alloys, as their name indicates, are alloys with enhanced corrosion resistance. Some ferrous and many non-ferrous metals and alloys are widely used in corrosive environments. In all cases, it strongly depends on certain environment and other conditions. Corrosion-resistant alloys are used for water piping and many chemical and industrial applications. In case of ferrous alloys, we are talking about stainless steels and to some extent about cast irons. But some non-ferrous corrosion-resistant alloys exhibit remarkable corrosion resistance nad therefore they may be used for many special purposes. There are two main reasons why nonferrous materials are preferred over steels and stainless steels for many of these applications. For example, many of the non-ferrous metals and alloys possess much higher resistance to corrosion than available alloy steels and stainless steel grades. Second, a high strength-to-weight ratio or high thermal and electrical conductivity may provide a distinct advantage over a ferrous alloy.

Density of Corrosion-resistant Alloys

Density of typical aluminium bronze is 7.45 g/cm³ (UNS C95400).

Density of typical superalloy is 8.22 g/cm³ (Inconel 718).

Density of typical titanium alloy is 4.51 g/cm³ (Grade 2).

Density of typical aluminium alloy is 2.7 g/cm³ (6061 alloy).

Density of typical stainless steel is 8.0 g/cm³ (304 steel).

Density is defined as the mass per unit volume. It is an intensive property, which is mathematically defined as mass divided by volume:

ρ = m/V

In words, the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance. The standard SI unit is kilograms per cubic meter (kg/m³). The Standard English unit is pounds mass per cubic foot (lbm/ft³).

Since the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance, it is obvious, the density of a substance strongly depends on its atomic mass and also on the atomic number density (N; atoms/cm³),

• Atomic Weight. The atomic mass is carried by the atomic nucleus, which occupies only about 10^-12 of the total volume of the atom or less, but it contains all the positive charge and at least 99.95% of the total mass of the atom. Therefore it is determined by the mass number (number of protons and neutrons).
• Atomic Number Density. The atomic number density (N; atoms/cm³), which is associated with atomic radii, is the number of atoms of a given type per unit volume (V; cm³) of the material. The atomic number density (N; atoms/cm³) of a pure material having atomic or molecular weight (M; grams/mol) and the material density (⍴; gram/cm³) is easily computed from the following equation using Avogadro’s number (N_A = 6.022×10²³ atoms or molecules per mole):
• Crystal Structure. Density of crystalline substance is significantly affected by its crystal structure. FCC structure, along with its hexagonal relative (hcp), has the most efficient packing factor (74%). Metals containing FCC structures include austenite, aluminum, copper, lead, silver, gold, nickel, platinum, and thorium.

See above:
Corrosion-resistant Alloys

Corrosion-resistant alloys, as their name indicates, are alloys with enhanced corrosion resistance. Some ferrous and many non-ferrous metals and alloys are widely used in corrosive environments. In all cases, it strongly depends on certain environment and other conditions. Corrosion-resistant alloys are used for water piping and many chemical and industrial applications. In case of ferrous alloys, we are talking about stainless steels and to some extent about cast irons. But some non-ferrous corrosion-resistant alloys exhibit remarkable corrosion resistance nad therefore they may be used for many special purposes. There are two main reasons why nonferrous materials are preferred over steels and stainless steels for many of these applications. For example, many of the non-ferrous metals and alloys possess much higher resistance to corrosion than available alloy steels and stainless steel grades. Second, a high strength-to-weight ratio or high thermal and electrical conductivity may provide a distinct advantage over a ferrous alloy.

Properties of Corrosion-resistant Alloys

Material properties are intensive properties, that means they are independent of the amount of mass and may vary from place to place within the system at any moment. The basis of materials science involves studying the structure of materials, and relating them to their properties (mechanical, electrical etc.). Once a materials scientist knows about this structure-property correlation, they can then go on to study the relative performance of a material in a given application. The major determinants of the structure of a material and thus of its properties are its constituent chemical elements and the way in which it has been processed into its final form.

Density of Corrosion-resistant Alloys

Density of typical aluminium bronze is 7.45 g/cm³ (UNS C95400).

Density of typical superalloy is 8.22 g/cm³ (Inconel 718).

Density of typical titanium alloy is 4.51 g/cm³ (Grade 2).

Density of typical aluminium alloy is 2.7 g/cm³ (6061 alloy).

Density of typical stainless steel is 8.0 g/cm³ (304 steel).

Density is defined as the mass per unit volume. It is an intensive property, which is mathematically defined as mass divided by volume:

ρ = m/V

In words, the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance. The standard SI unit is kilograms per cubic meter (kg/m³). The Standard English unit is pounds mass per cubic foot (lbm/ft³).

Since the density (ρ) of a substance is the total mass (m) of that substance divided by the total volume (V) occupied by that substance, it is obvious, the density of a substance strongly depends on its atomic mass and also on the atomic number density (N; atoms/cm³),

• Atomic Weight. The atomic mass is carried by the atomic nucleus, which occupies only about 10^-12 of the total volume of the atom or less, but it contains all the positive charge and at least 99.95% of the total mass of the atom. Therefore it is determined by the mass number (number of protons and neutrons).
• Atomic Number Density. The atomic number density (N; atoms/cm³), which is associated with atomic radii, is the number of atoms of a given type per unit volume (V; cm³) of the material. The atomic number density (N; atoms/cm³) of a pure material having atomic or molecular weight (M; grams/mol) and the material density (⍴; gram/cm³) is easily computed from the following equation using Avogadro’s number (N_A = 6.022×10²³ atoms or molecules per mole):
• Crystal Structure. Density of crystalline substance is significantly affected by its crystal structure. FCC structure, along with its hexagonal relative (hcp), has the most efficient packing factor (74%). Metals containing FCC structures include austenite, aluminum, copper, lead, silver, gold, nickel, platinum, and thorium.

Mechanical Properties of Corrosion-resistant Alloys

Materials are frequently chosen for various applications because they have desirable combinations of mechanical characteristics. For structural applications, material properties are crucial and engineers must take them into account.

Strength of Corrosion-resistant Alloys

In mechanics of materials, the strength of a material is its ability to withstand an applied load without failure or plastic deformation. Strength of materials basically considers the relationship between the external loads applied to a material and the resulting deformation or change in material dimensions. Strength of a material is its ability to withstand this applied load without failure or plastic deformation.

Ultimate Tensile Strength

Ultimate tensile strength of aluminium bronze – UNS C95400 is about 550 MPa.

Ultimate tensile strength of superalloy – Inconel 718 depends on heat treatment process, but it is about 1200 MPa.

Ultimate tensile strength of commercially pure titanium – Grade 2 is about 340 MPa.

Ultimate tensile strength of 6061 aluminium alloy depends greatly on the temper of the material, but for T6 temper it is about 290 MPa.

Ultimate tensile strength of stainless steel – type 304 is 515 MPa.

The ultimate tensile strength is the maximum on the engineering stress-strain curve. This corresponds to the maximum stress that can be sustained by a structure in tension. Ultimate tensile strength is often shortened to “tensile strength” or even to “the ultimate.”  If this stress is applied and maintained, fracture will result. Often, this value is significantly more than the yield stress (as much as 50 to 60 percent more than the yield for some types of metals). When a ductile material reaches its ultimate strength, it experiences necking where the cross-sectional area reduces locally. The stress-strain curve contains no higher stress than the ultimate strength. Even though deformations can continue to increase, the stress usually decreases after the ultimate strength has been achieved. It is an intensive property; therefore its value does not depend on the size of the test specimen. However, it is dependent on other factors, such as the preparation of the specimen, the presence or otherwise of surface defects, and the temperature of the test environment and material. Ultimate tensile strengths vary from 50 MPa for an aluminum to as high as 3000 MPa for very high-strength steels.

Yield Strength

Yield strength of aluminium bronze – UNS C95400 is about 250 MPa.

Yield strength of superalloy – Inconel 718 depends on heat treatment process, but it is about 1030 MPa.

Yield strength of commercially pure titanium – Grade 2 is about 300 MPa.

Yield strength of 6061 aluminium alloy depends greatly on the temper of the material, but for T6 temper it is about 240 MPa.

Yield strength of stainless steel – type 304 is  205 MPa.

The yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning plastic behavior. Yield strength or yield stress is the material property defined as the stress at which a material begins to deform plastically whereas yield point is the point where nonlinear (elastic + plastic) deformation begins. Prior to the yield point, the material will deform elastically and will return to its original shape when the applied stress is removed. Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible. Some steels and other materials exhibit a behaviour termed a yield point phenomenon. Yield strengths vary from 35 MPa for a low-strength aluminum to greater than 1400 MPa for very high-strength steels.

Young’s Modulus of Elasticity

Young’s modulus of elasticity of aluminium bronze – UNS C95400 is about 110 GPa.

Young’s modulus of elasticity of superalloy – Inconel 718 is 200 GPa.

Young’s modulus of elasticity of commercially pure titanium – Grade 2 is about 105 GPa.

Young’s modulus of elasticity of 6061 aluminium alloy is about 69 GPa.

Young’s modulus of elasticity stainless steel – type 304 and 304L is 193 GPa.

The Young’s modulus of elasticity is the elastic modulus for tensile and compressive stress in the linear elasticity regime of a uniaxial deformation and is usually assessed by tensile tests. Up to a limiting stress, a body will be able to recover its dimensions on removal of the load. The applied stresses cause the atoms in a crystal to move from their equilibrium position. All the atoms are displaced the same amount and still maintain their relative geometry. When the stresses are removed, all the atoms return to their original positions and no permanent deformation occurs. According to the Hooke’s law, the stress is proportional to the strain (in the elastic region), and the slope is Young’s modulus. Young’s modulus is equal to the longitudinal stress divided by the strain.

Hardness of Corrosion-resistant Alloys

Brinell hardness of aluminium bronze – UNS C95400 is approximately 170 MPa.

Brinell hardness of superalloy – Inconel 718 depends on heat treatment process, but it is approximately 330 MPa.

Rockwell hardness of commercially pure titanium – Grade 2 is approximately 80 HRB.

Brinell hardness of 6061 aluminium alloy depends greatly on the temper of the material, but for T6 temper it is approximately 95 MPa.

Brinell hardness of stainless steel – type 304 is approximately 201 MPa.

Rockwell hardness test is one of the most common indentation hardness tests, that has been developed for hardness testing. In contrast to Brinell test, the Rockwell tester measures the depth of penetration of an indenter under a large load (major load) compared to the penetration made by a preload (minor load). The minor load establishes the zero position. The major load is applied, then removed while still maintaining the minor load. The difference between depth of penetration before and after application of the major load is used to calculate the Rockwell hardness number. That is, the penetration depth and hardness are inversely proportional. The chief advantage of Rockwell hardness is its ability to display hardness values directly. The result is a dimensionless number noted as HRA, HRB, HRC, etc., where the last letter is the respective Rockwell scale.

The Rockwell C test is performed with a Brale penetrator (120°diamond cone) and a major load of 150kg.

&nbsp;

See above:
Corrosion-resistant Alloys