Stainless steel / UNS S44004
440C is a high-carbon 17% chromium martensitic stainless steel that reaches the highest hardness of the standard stainless grades (around 58–60 HRC after hardening) for wear-resistant parts.
- UNS S44004
- W.Nr. 1.4125
- Spec ASTM A276
- Density 7.65 g/cm³
Also known as / equivalents
| System | Designation |
|---|---|
| UNS | S44004 |
| W.Nr. | 1.4125 |
| EN | X105CrMo17 |
| JIS | SUS440C |
| Also known as | AISI 440C, 1.4125, SUS440C |
Chemical composition
| Element | Min % | Max % |
|---|---|---|
| C | 0.95 | 1.20 |
| Mn | — | 1.00 |
| P | — | 0.040 |
| S | — | 0.030 |
| Si | — | 1.00 |
| Cr | 16.0 | 18.0 |
| Mo | — | 0.75 |
| Fe | Bal. | — |
Physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.65 g/cm³ | 0.276 lb/in³ |
| Magnetic response | Magnetic | — |
Available forms & specifications
| Form | Specification | Size range |
|---|---|---|
| Sheets, plates & coils | ASTM A240 / ASME SA240 | 0.3 mm – 6 mm |
| Seamless & welded pipe | ASTM A312 / ASME SA312 | 1/8" – 24" NB |
| Tubes | ASTM A213, A249, A269 | 1/8" – 24" NB |
| Bars & rods | ASTM A276, A479 | 3 mm – 500 mm |
| Flanges & forgings | ASTM A182 / ASME SA182 | 1/2" – 48" NB (larger on request) |
| Buttweld fittings | ASTM A403 / ASME SA403 | 1/2" – 48" NB |
| Fasteners | ASTM A193 / A194, F593 / F594 | M3 – M56 |
Corrosion & temperature resistance
Corrosion resistance rises with chromium, molybdenum and nitrogen: 304 handles general atmospheric and food-contact service, 316/317 add resistance to chlorides and pitting, 904L handles strong reducing acids, and stabilised 321/347 resist intergranular attack after welding or high-temperature exposure.
Applications
SS 440C: Bearings, valve seats, nozzles, knives. Process piping, tanks and vessels, heat exchangers, food, dairy and pharmaceutical equipment, architectural work and general engineering.
Frequently asked questions
What is the UNS number of SS 440C?
SS 440C is designated UNS S44004 (W.Nr. 1.4125, EN X105CrMo17).
What is SS 440C used for?
Highest hardness stainless. Typical uses: bearings, valve seats, nozzles, knives.
Is SS 440C magnetic?
Magnetic.
In which forms can I buy SS 440C from Rajkamal Metals?
Coils & Strips, Sheets & Plates, Pipes & Tubes, Round Bars & Rods, Structural Sections, Flanges, Buttweld Fittings, Socket Weld & Threaded Fittings, Fasteners, Ferrule / Instrumentation Fittings, Dairy Fittings, Dish Ends, SS Tanks, Custom Orders. Sizes as per standard; other sizes on request.
Do you supply a Mill Test Certificate with SS 440C?
Yes. Actual values are given in the Mill Test Certificate (EN 10204 3.1) supplied with each order.
Last updated: 30 October 2026. Grade names identify the supply range; designations are not engineering equivalents. Availability, make, origin and documentation are confirmed at quotation.
Request a quote
Need SS 440C?
Send the grade, form, size, quantity and destination. Price on request — every offer is prepared against your specification.