431 stainless steels are martensitic, heat-treatable grades with excellent corrosion resistance, torque strength, high toughness and tensile properties. All these properties make them ideal for bolt and shaft applications. These steels, however, cannot be cold-worked owing to their high yield strength, hence they are suitable for operations such as spinning, deep drawing, bending or cold heading.
Fabrication of martensitic steels is generally carried out using techniques that allow hardening and tempering treatments and poor weldability. The corrosion resistance properties of grade 431 steels are lower than that of austenitic grades. The operations of grade 431 are limited by their loss of strength at high temperatures, due to over-tempering, and loss of ductility at negative temperatures.
Corrosion Resistance: 431 stainless steel has good corrosion resistance in a wide range of environments. It can withstand exposure to water, mild acids, and other corrosive substances without corroding or rusting.
Strength: 431 stainless steel has high strength and hardness, making it ideal for applications that require high mechanical strength. It has a minimum tensile strength of 760 MPa and a minimum yield strength of 345 MPa.
Ductility: 431 stainless steel has moderate ductility, which means that it can be formed and shaped, but not as easily as other types of stainless steel. This property makes it suitable for applications that require moderate ductility.
Weldability: 431 stainless steel is easily weldable, but it may require preheating to prevent cracking. It can be welded using common welding techniques, such as TIG, MIG, and resistance welding.
Magnetic Properties: 431 stainless steel is magnetic, which makes it suitable for applications that require magnetic properties.
Heat Resistance: 431 stainless steel has good heat resistance and can withstand moderately high temperatures without losing its strength or corrosion resistance. It can withstand temperatures up to 760°C (1400°F) without undergoing any significant change in its properties.
Composition ranges of grade 431 stainless steels
| Grade | C | Mn | Si | P | S | Cr | Ni | |
| 431 | min. | - | - | - | - | - | 15 | 1.25 |
| max. | 0.2 | 1 | 1 | 0.04 | 0.03 | 17 | 2.5 | |
| Condition | Annealed | *T | |
| Tensile Strength (MPa) | Min | 850 | |
| Max | 1000 | ||
| 0.2% Yield Strength (MPa) | Min | 635 | |
| Elongation on 5.65√S0 % | Min | 11 | |
| Izod Impact Valua J mm | Min | 63 34 | |
| 63 20 | |||
| Hardness HB | Min | 248 | |
| Max | 277 | 302 |
Qinghe Steel is a full line supplier and processer of stainless steel coil, sheet, plate, bar, and strip products. We stock many grades of stainless steel, including 300 and 400 series stainless, annealed and in various tempers and high temperature grades, for shipments worldwide. View our steel center here
Full anneal — Full annealing cannot be performed on grade 431 steels. This grade gets hardened even during slow cooling.
Process anneal — Grade 431 steels are heated to 620 to 660°C and then air-cooled.
Grade 431 steels are generally hardened by heating at temperatures from 980 to 1065°C, holding for nearly ½ h, followed by oil or air quenching. Complex or hardened parts of grade 431 steels can be pre-heated to temperatures from 760 to 790°C and tempered, to improve their mechanical properties. Tempering of these steels at 425 to 600°C should be avoided, owing to the loss of impact toughness at this temperature range.
Welding of grade 431 stainless steels is difficult due to the chances of cracking. It is recommended to pre-heat the materials to 200 - 300°C before welding, and carry out post-weld heat treatment at 650°C. Welding can be performed using grade 410 filler rods, but ductile welds can be achieved using grades 308L, 309 or 310 steels.
Grade 431 steels can be easily machined in their annealed state. However, it is extremely difficult to machine these steels if they are hardened above 30HRC.
Typical applications of grade 431 stainless steels include the following:
Qinghe Steel is a full line supplier and processer of 431 stainless steel coil, sheet, plate, bar, and strip products. We stock many grades of stainless steel, including 300 and 400 series stainless, annealed and in various tempers and high temperature grades, for shipments worldwide. View our steel center here
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