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| PRODUCT DATA of AISI 431 |
| Material | AISI 431 |
| Product Datasheet | Carpenter 431 Aubert Duval 431 |
| General Information | Martensitic stainless steel. This alloy is a modification of Type 410 stainless steel with increased chromium and carbon contents and an addition of about 2 percent nickel. It is on the borderline of a heat treatable stainless steel. Because of the rather broad composition limits, it may require special considerations regarding heat treatment. It is normally used at temperatures up to 425C where moderate strength is required and provides corrosion resistance superior to other hardenable chromium stainless grades. It is frequently used in highly stressed parts where good corrosion resistance is important in design, such as aircraft fittings, pump shafts and valve parts |
| Precautions | Hydrogen embrittlement may be a problem with this steel at high strength and hardness levels. Embrittlement may be caused by cleaning processes such as pickling. |
| Chemical Composition | Fe-16Cr-2Ni-0.2C |
| Name of Manufacturer | Aubert and Duval
22, rue Henri-Vuillemin • 92230 Gennevilliers - France 33 (0)1 55 02 58 00 33 (0)1 55 03 58 01 dircom@aubertduval.com www.aubertduval.com |
| PHYSICAL PROPERTIES |
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| Crystal Structure | Face centered cubic (fcc) |
| Specific Gravity | 7.74 |
| Magnetic Properties | Ferromagnetic |
| ELECTRICAL PROPERTIES |
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| Electrical Volume Resistivity | 7.2e-7 ohm.m |
| THERMAL PROPERTIES |
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| Thermal Expansion Coefficient | 10 μstrain/°C |
| Melting Range | 1430 to 1510 °C |
| RELEVANT PROPERTIES FOR USE IN SPACE COMMUNITY |
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| General Corrosion Status | No specific corrosion protection required |
| Corrosion/Thermal | The corrosion resistance of Type 431 is superior to other hardenable chromium stainless steels, but is generally inferior to the 18-8 types |
| Stress Corrosion Status | Moderate Resistance to SCC: Table 2 Remark:Requires Stress corrosion evaluation form Data Quality: Design Data |
| EMF vs SCE | -0.17 V Remark: Measured in 3.5% NaCl solution. Passive condition Data Quality: Design Data |
| Bimetallic Corrosion | Can be connected without any restriction to: Cr, Au, Ag, Gun-metal, P-bronzes, Sn-bronzes, Ti+alloys, Ni, Monel, Inconel, Ni/Mo alloys
Can be connected in a non-controlled environment to the above and Cd, austenitic cast iron, Cu, Brasses, Al-bronzes, Si-bronzes, Au, Pt, C, Rh, Sn-Pb alloys, Sn, Pb, 300 series stainless steels Can be connected in a clean room environment to above and Al-Cu alloys Needs specific measures: All others Test:ECSS-Q-ST-70C Rev.1 Table 5.1 Data Quality: Design Data |
| Machinability | Because of the relative high hardness of this steel in the semi-annealed condition, machinability is poorer than the other 400 grades. Machinability is superior to the 18-8 stainless steels |
| Welding | Welding is recommended only for parts used at elevated temperatures. Welds show grain growth that causes embrittlement at room temperature |