431 STAINLESS STEEL
Hardenable Martensitic Stainless Steel Alloy
Type 431 is a hardenable martensitic stainless steel alloy which has a combination of high tensile and torsional strength - this makes it well suited to shaft manufacture.
The alloy is intended for use in applications requiring good strength and toughness combined with reasonable corrosion resistance. As the alloy offers considerable resistance to saltwater corrosion, it is used widely in marine equipment and systems.
Type 431 is easily machined in the annealed state but welding is difficult due to cracking and it is recommended that the material is preheated to improve welding performance.
| TYPICAL APPLICATIONS |
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| • Marine systems • Pump & propeller shafts • Outboard motor drive shafts • Valve stems • Aircraft components • Axles |
| KEY FEATURES |
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• Heat treatable martensitic stainless steel |
| MACHINABILITY |
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| Risk of cracking. Pre-heating recommended. |
| WELDABILITY |
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Risk of cracking. Pre-heating recommended. |
| AVAILABILITY |
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| Round bar, plate, sheet and tube |
| CORROSION RESISTANCE |
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Similar to Type 304 stainless steel. Considerable resistance |
RELATED SPECIFICATIONS
BS 970 431S29T 1.4057 X17CrNi16-2
X16CrNi16 AISI ASTM UNS S43100
| TYPICAL CHEMICAL COMPOSITION | ||
|---|---|---|
| PREn = Pitting Resistance Equivalent
PREn= Cr% + 3.3Mo% + 16N% |
Carbon | 0.02% Max |
| Silicon | 0.80% Max | |
| Manganese | 1.00% Max | |
| Phosphorous | 0.030% Max | |
| Sulphur | 0.010% Max | |
| Chromium | 19.5 – 20.5% | |
| Nickel | 17.5 – 18.5% | |
| Molybdenum | 6.0 – 6.5% | |
| Nitrogen | 0.18 – 0.22% | |
| Copper | 0.50 – 1.00% | |
| PREn | >40 | |
| MECHANICAL PROPERTY REQUIREMENTS - ANNEALED CONDITION | ||||
|---|---|---|---|---|
| Yield | Tensile Strength | Elongation | Charpy Impact @ Rt J | Hardness |
| >300Mpa (44KSI) | 650 – 850Mpa (94 – 123KSI) |
35% | 100 | 260HB Max |
| PHYSICAL PROPERTIES | ||||
|---|---|---|---|---|
| Density | Modulus of Elasticity | Electrical Resistivity | Thermal Conductivity at 100°C | |
| 7800 kg/m3 | 200GPa | 720 n. Ω.m | 20.2 W/m.K | |