440C
Data verified440C is a high-carbon martensitic stainless capable of the highest hardness of any standard stainless grade, used for bearings, knife blades and wear parts. Its large chromium carbides give edge retention but limit toughness and corrosion resistance relative to its chromium content.
Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.95–1.20 |
| Si | ≤1.00 |
| Mn | ≤1.00 |
| P | ≤0.040 |
| S | ≤0.030 |
| Cr | 16.00–18.00 |
| Mo | ≤0.75 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Delivery condition | Annealed (hardened for use) |
| Hardness (hardened) | 58–60 HRC |
| Tensile strength | 760–2030 MPa (condition dependent) |
| Density | 7.70 g/cm³ |
| Magnetic | Yes |
Heat treatment
Anneal 845–900 °C slow cool; harden 1010–1065 °C oil/air (sub-zero treatment improves stability); temper 150–370 °C.
Equivalent grades
| Standard | Designation |
|---|---|
| din | 1.4125 |
| aisi | 440C |
| jis | SUS440C |
| gb | 102Cr17Mo |
Compare side by side: 440C vs 440B · 440C vs 440A
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Ball bearings and races, premium knife blades, valve seats, surgical instruments, wear components.
Processing: Difficult to machine and grind due to carbide volume; weldability negligible; corrosion resistance is moderate and best when hardened and finely polished.
FAQ
- Is 440C a good knife steel?
- Yes for edge retention: at 58–60 HRC it holds an edge far longer than 420, though it is harder to sharpen and less tough, so blade geometry must avoid thin, brittle edges.
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Ask for a quotationVisit NasteelSource: ASTM A276 / EN 10088 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.
