Advantages
431 stainless steel is a high chromium-low nickel high hardenability Martensitic stainless steel with high strength and good corrosion resistance, as generally supplied hardened and tempered in the tensile range 850 – 1000 Mpa (condition T) Brinell range 248 – 302. Characterized by very good corrosion resistance in general atmospheric corrosive environments, good resistance to mild marine and industrial atmospheres, resistant to many organic materials, nitric acid and petroleum products coupled with high tensile and high yield strength plus excellent toughness in the hardened and tempered condition.
431 due to its excellent hardenability is capable of being through hardened up to Rc44, depending upon carbon content and section size. Small sections can be air cooled and larger sections oil quenched for maximum through hardness. Pre-hardened and tempered 431 will also respond readily to nitriding achieving a typical surface hardness of over Rc65. The nitriding process however reduces the corrosion resistance and is therefore not generally recommended except for critical applications where the benefit outweighs all other considerations.
Chemical Analysis Weight % (all values are maximum unless a range is otherwise indicated)
| Chromium | 15.0 min.-17.0 max. | Phosphorus | 0.04 |
| Nickel | 1.25 min.-2.5 max. | Sulfur | 0.03 |
| Carbon | 0.2 | Silicon | 1.0 |
| Manganese | 1.0 | Iron | Balance |
Properties
Mechanical Property Requirements For Material in the Annealed and Heat Treated – Condition T To AS2837 – 1986 431 and BS970 Part 3 1991 431S29
| 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 |
Applications
431 stainless steel bar has a good oxidation resistance and intensity of medium temperature. So it is widely used in decoration, sugical instruments, household appliances, cookware, automobile and other industry construction. 431 stainless steel bar has high strength, but poor plasticity and weldability. The commonly used grades of martensitic stainless steel are 1Cr13, 3Cr13, etc. Because of its high carbon content, it has high strength, hardness and wear resistance, but its corrosion resistance is slightly poor. It is used for springs, steam turbine blades, hydraulic valves and other parts with high mechanical properties and general corrosion resistance requirements. It is used after quenching and tempering. Annealing treatment is required after forging and stamping.
