321 stainless steel is a Cr-Ni-Ti Austenitic stainless steel grade, and it is similar to 304 stainless steel, but with better resistance to intergranular corrosion due to the addition of titanium element and high-temperature strength. The addition of titanium is effective in controlling the formation of chromium carbide.
321 stainless steel has excellent high-temperature stress rupture properties and high-temperature creep properties, its mechanical properties are better than 304 stainless steel, and it is also heat-resistant steel, better in high temperatures than 316L. Grade 321 is the grade of choice for applications in the temperature range of up to about 900 °C, combining high strength, resistance to scaling, and phase stability with resistance to subsequent aqueous corrosion. 321 stainless steel has good wear and corrosion resistance in the oxidizing medium for the manufacture of wear-resistant acid containers and equipment lining, pipelines.
321 Stainless Steel Composition
- Carbon (C): ≤ 0.08%
- Silicon (Si): ≤1.00%
- Manganese (Mn): ≤2.00%
- Phosphorus (P): ≤0.045%
- Sulphur (S): ≤0.030%
- Nickel (Ni): 9.00%～12.00%
- Chromium (Cr): 17.00% ~ 19.00%
- Titanium (Ti): ≥5 × C%
321 vs 1.4541 in Composition
| Standard | Grade | C | Mn | Cr | Ni | Mo | N | Other |
|---|---|---|---|---|---|---|---|---|
| ASME II A SA-240 | 321 | ≤0.08 | ≤2.00 | 17.0-19.0 | 9.0-12.0 | ≤0.10 | ||
| ASTM A240 | 321 | ≤0.08 | ≤2.00 | 17.0-19.0 | 9.0-12.0 | ≤0.10 | Ti 5 X C Min – 0.70 Max | |
| EN 10028-7 | 1.4541 | ≤0.08 | ≤2.00 | 17.0-19.0 | 9.0-12.0 | |||
| EN 10088-2 | 1.4541 | ≤0.08 | ≤2.0 | 17.0-19.0 | 9.0-12.0 | |||
| EN 10088-4 | 1.4541 | ≤0.08 | ≤2.0 | 17.0-19.0 | 9.0-12.0 | |||
| GOST 5632-72 | 08X18H10T | ≤0.08 | ≤2.0 | 17.00-19.00 | 9.00-11.00 | ≤0.35 | ≤0.10 | |
| GOST 5632-72 | 12X18H10T | ≤0.12 | ≤2.0 | 17.0-19.0 | 9.0-11.0 | ≤0.35 | ≤0.10 |
321 Stainless Steel Mechanical Property
- Tensile strength: ≥520 MPa
- Yield strength: ≥205 MPa
- Elongation: ≥40%
- Hardness ≤187HB; ≤90HRB; ≤200HV
321 vs 1.4541 in Mechanical Properties
| Standard | Grade | YS Rp0.2 | YS Rp1.0 | TS Rm | Elongation | Rockwell | HB |
|---|---|---|---|---|---|---|---|
| MPa | MPa | MPa | % | ||||
| ASME II A SA-240 | 321 | ≥ 205 | ≥ 515 | ≤ 217 | |||
| ASTM A240 | 321 | ≥ 205 | ≥ 515 | ≤ 95HRB | ≤ 217 | ||
| EN 10028-7 | 1.4541 | ≥ 220 | ≥ 250 | 520-720 | ≥ 40 | ||
| EN 10088-2 | 1.4541 | ≥ 220 | ≥ 250 | 520-720 | ≥ 40 | ||
| EN 10088-4 | 1.4541 | ≥ 220 | ≥ 250 | 520-720 | ≥ 40 | ||
| GOST 5632-72 | 08X18H10T | ≥ 235 | ≥ 250 | ≥ 535 | ≥ 40 | ||
| GOST 5632-72 | 12X18H10T | ≥ 230 | ≥ 260 | 540-670 | ≥ 45 |
321 Stainless Steel Equivalent
| AISI | UNS | DIN | EN | JIS | GB |
|---|---|---|---|---|---|
| 321 | 32100 | 1.4541 | X6CrNiTi18-10 | SUS321 | 0Cr18Ni10Ti |
321 Stainless Steel Physical Properties
| Physical Properties | Value |
|---|---|
| Density, g/cm3 (lb/in.3) | 7.9 (0.29) |
| Melting point, °C (°F) | 1400-1425 (2550-2600) |
| Specific heat capacity, J/kg·K (Btu/lb ·°F) | 500 (0.12) at 20 °C |
| Electrical resistivity, μΩ·m | 0.72 at 20 °C |
| Magnetic permeability | 1.02 (Approximate) |
| Elastic modulus, GPa (106 psi) | 193 (28) |
| Thermal conductivity, W/m·K (Btu/ft · h ·°F) | 16.1 (9.3) at 100 °C (212 °F) |
| 22.2 (12.8) at 500 °C (932 °F) | |
| Coefficient of thermal expansion, 10-6/K (μin./in. ·°F) | 16.6 (9.2) at 0-100 °C (32-212 °F) |
| 17.2 (9.6) at 0-315 °C (32-600 °F) | |
| 18.6 (10.3) at 0-538 °C (32-1000 °F) |
Forms
Corrosion Resistance
321 stainless steel exhibits good general corrosion resistance, and excellent resistance to intergranular corrosion after exposure to temperatures in the chromium carbide precipitation range of 800 – 1500°F (427 – 816°C), 321 resists oxidation to 1500°F (816°C) and has higher creep and stress rupture properties than alloys 304 and 304L.
Heat Resistance
Good oxidation resistance in intermittent service to 900°C and in continuous service to 925°C. These grades perform well in the 425-900°C range, and particularly where subsequent aqueous corrosive conditions are present, they also possess good low-temperature toughness.
Heat Treatment
Heat temperature range is limited to 950-1120°C and cool rapidly for maximum corrosion resistance, it cannot be hardened by heat treatment.
Dual Certification
Dual 321/321H stainless steel is usually used for high-temperature applications.
Notes
- Perform not well in chloride solutions, even in small concentrations, or in sulfuric acid service
- Grade 321 stainless steel does not polish well so that not recommended for decorative applications
- Excellent weldability by all standard fusion methods, both with and without filler metals
321/321H Stainless Steel Comparison
Grade 321H is a modification of 321 with higher carbon content, to provide improved high-temperature strength.
| C | Si | Mn | P | S | Cr | Ni | Ti | N | |
|---|---|---|---|---|---|---|---|---|---|
| 321 | 0.08 | 1.00 | 2.00 | 0.045 | 0.030 | 17.0-19.0 | 9.0-12.0 | 5 X C Min – 0.70 Max | 0.10 |
| 321H | 0.04 -0.10 | 1.00 | 2.00 | 0.045 | 0.030 | 17.0-19.0 | 9.0-12.0 | 4 X C Min – 0.70 Max | – |
| Tensile Strength(Mpa) | Yield Point(Mpa) | Elongation(%) | Hardness(HRB) | |
|---|---|---|---|---|
| 321 | 515 | 205 | 40 | 95 |
| 321H | 515 | 205 | 40 | 95 |
Applications
- Petrochemical industry: 321 stainless steel has a wide range of applications in the petrochemical industry, due to its excellent high-temperature stress-breaking performance and high-temperature resistance to latent change performance, it can withstand high-temperature environment stress, so often used in petrochemical equipment.
- Power industry: in the power industry, 321 stainless steel also has outstanding performance, can withstand high temperatures and high-pressure environments, commonly used in the manufacture of boiler steam bags and other equipment.
- Bridge construction: in bridge construction, 321 stainless steel for its good corrosion resistance and mechanical properties, is used in a variety of bridge structures, increasing the durability and safety of the bridge.
- Automotive manufacturing: In the automotive industry, 321 stainless steel is used to manufacture components such as exhaust pipes, which can withstand high temperatures and corrosion to ensure the performance and life of the car.
- Aircraft manufacturing: Due to its excellent high-temperature resistance, 321 stainless steel is also used in the manufacture of aircraft, especially in the application of exhaust pipes and high-temperature components.
304 vs 321 Stainless Steel
Firstly, from the material composition, the main components of both 321 stainless steel and 304 stainless steel are iron, chromium and nickel. However, there are some differences in their alloy compositions. 304 stainless steel has a relatively simple alloy composition that focuses on providing good corrosion resistance and formability. In contrast, 321 stainless steel contains additional elements of titanium or niobium, which are added to give 321 stainless steel better strength and creep properties at high temperatures.
In terms of mechanical properties, both 321 stainless steel and 304 exhibit good strength, ductility and toughness. However, since 321 stainless steel contains titanium or niobium elements, these elements help improve its strength and creep properties at high temperatures. As a result, the mechanical properties of 321 stainless steel may be superior to those of 304 stainless steel in high-temperature environments.
Corrosion resistance is one of the important properties of stainless steel. In this regard, both 321 stainless steel and 304 show good corrosion resistance, especially under general environmental conditions. However, in some specific environments, such as high temperatures, strong corrosive media, etc., the corrosion resistance of 321 stainless steel may be more superior. This is because the titanium or niobium elements in 321 stainless steel help to reduce intergranular corrosion, thereby improving the material’s corrosion resistance in these harsh environments.
In addition, due to the differences in composition and properties, there are also some differences in the application areas of 321 stainless steel and 304 stainless steel. 304 stainless steel is widely used in the industrial and furniture decoration industry as well as the food and medical industry due to its good corrosion resistance and formability. And 321 stainless steel due to its excellent high-temperature stress-breaking performance and high-temperature creep resistance, is more suitable for the manufacture of welded components used at high temperatures, such as petroleum exhaust gas combustion pipelines, engine exhaust, boiler shells and so on.
316 vs 321 Stainless Steel
Firstly, they have different alloy compositions.321 stainless steel contains titanium, which makes it have better high-temperature resistance performance, suitable for use in high-temperature environments. 316 stainless steel contains molybdenum, which has better corrosion resistance, suitable for chemicals, marine environments and other occasions of strong corrosion.
Secondly, their mechanical properties are also different. Because 321 stainless steel contains titanium, so its strength and hardness are relatively high, but the plasticity and toughness are slightly lower than 316 stainless steel. While 316 stainless steel has good workability and plasticity, it can be easily processed into various shapes.
Finally, their prices also differ. Usually, the price of 321 stainless steel is slightly higher than that of 316 stainless steel, which is caused by its containing rare elements such as titanium.
Related References
- ASTM A240, Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications
- ASTM A480, Standard Specification for General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plate, Sheet, and Strip
- EN 10088-2, Stainless steels. Technical delivery conditions for sheet/plate and strip of corrosion-resisting steels for general purposes
- EN 10088-3, Stainless steels. Technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products of corrosion-resisting steels for general purposes
- EN 10088-4, Stainless steels. Technical delivery conditions for sheet/plate and strip of corrosion-resisting steels for construction purposes
- EN 10088-5, Stainless steels. Technical delivery conditions for bars, rods, wire, sections and bright products of corrosion-resisting steels for construction purposes
- ASTM A249, Standard Specification for Welded Austenitic Steel Boiler, Superheater, Heat-Exchanger, and Condenser Tubes
- ASTM A213, Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes
- ASTM A312, Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes
- ASTM A276, Standard Specification for Stainless Steel Bars and Shape