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MaterialAISI 431
Product DatasheetCarpenter 431
Aubert Duval 431
General InformationMartensitic 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
PrecautionsHydrogen 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 CompositionFe-16Cr-2Ni-0.2C
Name of ManufacturerAubert and Duval
22, rue Henri-Vuillemin • 92230 Gennevilliers - France
33 (0)1 55 02 58 00
33 (0)1 55 03 58 01
Crystal StructureFace centered cubic (fcc)
Specific Gravity7.74
Magnetic PropertiesFerromagnetic
Electrical Volume Resistivity7.2e-7 ohm.m
Thermal Expansion Coefficient10 μstrain/°C
Melting Range1430 to 1510 °C
General Corrosion StatusNo specific corrosion protection required
Corrosion/ThermalThe corrosion resistance of Type 431 is superior to other hardenable chromium stainless steels, but is generally inferior to the 18-8 types
Stress Corrosion StatusModerate 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 CorrosionCan 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
MachinabilityBecause 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
WeldingWelding is recommended only for parts used at elevated temperatures. Welds show grain growth that causes embrittlement at room temperature