431 stainless steel is a martensitic stainless alloy known for its high strength, good toughness, and moderate corrosion resistance. Thanks to its heat treatability, it is widely used in aerospace, marine, and mechanical components. In this guide, we explore key considerations for machining and post-treatment of 431 round bars.
Typical Chemical Composition (wt%)
| Element | C | Cr | Ni | Mn | Si | P | S |
|---|---|---|---|---|---|---|---|
| Content | ≤0.20 | 15.0–17.0 | 1.25–2.50 | ≤1.00 | ≤1.00 | ≤0.040 | ≤0.030 |
Mechanical Properties (After Heat Treatment)
| Property | Value |
|---|---|
| Hardness | Up to 285 HB (annealed), ≥ 40 HRC (hardened) |
| Tensile Strength | 850–1000 MPa |
| Yield Strength | 635 MPa (min) |
| Elongation | ≥15% |
Machining TipsCondition: Best machined in annealed condition (≤ 285 HB)
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Cutting Tools: Use carbide-tipped tools for better tool life
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Coolant: Essential for heat control and surface finish
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Speed & Feed: Reduce speed when work hardening is observed
Heat Treatment Process
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Hardening: Heat to 980–1065°C, then air or oil quench
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Tempering: 150–370°C to adjust hardness and ductility
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Annealing: 850–900°C followed by slow furnace cooling for softening
Applications
| Sector | Application Examples |
|---|---|
| Aerospace | Shafts, bolts, fasteners |
| Marine | Propeller shafts, valve stems |
| Machinery | Pump parts, high-strength pins |
431 stainless steel bar is a versatile and heat-treatable martensitic alloy suitable for high-performance applications. For precision machining and reliable post-treatment, choosing a professional supplier is crucial. Tongyi Metal offers high-quality 431 round bars with technical support and flexible processing services.
