440C Stainless (UNS S44004)
The hardest standard stainless steel: bearing-grade wear resistance at up to ~60 HRC with corrosion protection.
- UNS
- S44004
- W.Nr / EN
- 1.4125
- Density
- 7.8 g/cm³
- Service range
- To ~425 °C (hardness-limited)
About 440C Stainless
440C is a high-carbon martensitic stainless steel that hardens to about 58–60 HRC — the highest hardness of any standard stainless grade. Chromium carbides in a hardened martensitic matrix provide bearing-class wear resistance while the 16–18 % chromium matrix keeps useful corrosion resistance.
It is the standard corrosion-resistant material for rolling bearings, valve seats and cutting components. DMK Alloys supplies 440C as bars and blanks, annealed for machining or hardened and tempered to specification.
440C Stainless chemical composition (weight %)
| Element | Limit / range |
|---|---|
| Fe | Balance |
| C | 0.95 – 1.20 |
| Cr | 16.0 – 18.0 |
| Mo | ≤ 0.75 |
| Mn | ≤ 1.0 |
| Si | ≤ 1.0 |
| P | ≤ 0.04 |
| S | ≤ 0.03 |
Composition limits per the commonly referenced standards listed below. Order-specific limits may differ — confirm against the governing specification.
440C Stainless mechanical properties (typical)
| Condition / form | Tensile, MPa | 0.2% Yield, MPa | Elongation, % |
|---|---|---|---|
| Bar, annealed (machining condition) | ≈ 760 | ≈ 450 | ≈ 14 |
| Bar, hardened + tempered, ~58 HRC | ≈ 1970 | ≈ 1900 | ≈ 2 |
Values are typical or specification-minimum levels for guidance only — not a guarantee of properties. Certified values are established by testing against the ordered specification.
440C Stainless specifications & international equivalents
| System | Designation | Covers |
|---|---|---|
| UNS | S44004 | All product forms |
| AMS | AMS 5630 | Bars, forgings |
| AMS | AMS 5618 | Bars (premium melted) |
| ASTM | ASTM A276 Type 440C | Bars, shapes |
| W.Nr / EN | 1.4125 · X105CrMo17 | European cross-reference |
Cross-references are for guidance; the governing document is always the specification cited on your purchase order or drawing.
440C Stainless physical properties
| Property | Typical value |
|---|---|
| Density | 7.8 g/cm³ |
| Melting range | 1370 – 1480 °C |
| Modulus of elasticity (family-typical) | ≈ 190 – 210 GPa |
| Indicative service range | To ~425 °C (hardness-limited) |
Forms we manufacture
- Bars
- Blanks for bearings and tooling
- Machined components to drawing
Dimensional ranges and delivery conditions are confirmed per enquiry.
Where 440C Stainless earns its keep
Typically specified for:
- Rolling-element bearings
- Valve seats
- Balls
- Pump components
- Wear-critical parts
Also consider
17-4PH Stainless
UNS S17400 · W.Nr 1.4542AMS 5643 · AMS 5604
Martensitic precipitation-hardening stainless steel — high strength and corrosion resistance from a single low-distortion age.
4340 Alloy Steel
UNS G43400AMS 6414 · AMS 6415
The reference nickel–chromium–molybdenum steel: deep hardenability with dependable toughness across strength levels.
321 Stainless
UNS S32100 · W.Nr 1.4541AMS 5510 · AMS 5645
Titanium-stabilised austenitic stainless for welded assemblies in the 425–815 °C sensitisation range.
Request 440C Stainless to your specification
State the governing standard, form, dimensions, quantity and testing requirements — the export team responds with a manufacturer's quotation.