Stainless steel / UNS S42000
420 is a higher-carbon 13% chromium martensitic stainless steel that reaches high hardness after hardening, used where wear resistance and a polished edge are needed.
- UNS S42000
- W.Nr. 1.4021
- Spec ASTM A240
- Density 7.73 g/cm³
Also known as / equivalents
| System | Designation |
|---|---|
| UNS | S42000 |
| W.Nr. | 1.4021 |
| EN | X20Cr13 |
| JIS | SUS420J1 |
| Also known as | AISI 420, 1.4021, SUS420J1 |
Chemical composition
| Element | Min % | Max % |
|---|---|---|
| C | 0.15 | — |
| Mn | — | 1.00 |
| P | — | 0.040 |
| S | — | 0.030 |
| Si | — | 1.00 |
| Cr | 12.0 | 14.0 |
| Fe | Bal. | — |
Physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.73 g/cm³ | 0.279 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 420: Cutlery, surgical tools, moulds, shafts. Process piping, tanks and vessels, heat exchangers, food, dairy and pharmaceutical equipment, architectural work and general engineering.
SS 420 vs SS 410
| SS 420 | SS 410 | |
|---|---|---|
| UNS | S42000 | S41000 |
| Key property | High hardness after heat treatment | Hardenable martensitic |
| Typical use | Cutlery, surgical tools, moulds, shafts | Valve trim, pump shafts, cutlery, fasteners |
| Cr (wt %) | 12.0–14.0 | 11.5–13.5 |
| Ni (wt %) | — | ≤ 0.75 |
| Mo (wt %) | — | — |
| C (wt %) | 0.15 | 0.08–0.15 |
| Tensile / yield (min, MPa) | — | 450 / 205 |
Frequently asked questions
What is the UNS number of SS 420?
SS 420 is designated UNS S42000 (W.Nr. 1.4021, EN X20Cr13).
What is SS 420 used for?
High hardness after heat treatment. Typical uses: cutlery, surgical tools, moulds, shafts.
Is SS 420 magnetic?
Magnetic.
In which forms can I buy SS 420 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 420?
Yes. Actual values are given in the Mill Test Certificate (EN 10204 3.1) supplied with each order.
What is the difference between SS 420 and SS 410?
SS 420: high hardness after heat treatment. SS 410: hardenable martensitic. See the comparison table on this page.
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.
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