Stainless 420 · UNS S42000 · W. Nr. 1.4021 / 1.4028
Stainless 420 (S42000): composition, properties, fittings and flanges
Stainless 420 (S42000, W. Nr. 1.4021 / 1.4028) is Martensitic chromium stainless steel with higher carbon. Stainless 420 is specified at Chromium 12.00 - 14.00, Nickel 0.75 max. 420 raises carbon above 0.15 %, so it hardens to roughly 50 HRC - the standard choice for cutlery, surgical instruments, valve seats and plastic moulds…
- UNS
- S42000
- W. Nr.
- 1.4021 / 1.4028
- Density
- 7.75 g/cm³ (0.280 lb/in³)
- Key strength
- 655 MPa / 95 ksi
Identification and standards
| Short form | Stainless 420 · UNS S42000 · W. Nr. 1.4021 / 1.4028 |
|---|---|
| Classification | Martensitic chromium stainless steel with higher carbon |
| UNS | S42000 |
| Werkstoff number | 1.4021 / 1.4028 |
| Material family | Stainless Steel |
Chemical composition
| Element | Composition (wt %) | Why it is there |
|---|---|---|
| Chromium (Cr) | 12.00 - 14.00 | Corrosion resistance |
| Carbon (C) | 0.15 min | Hardening response |
| Manganese (Mn) | 1.00 max | - |
| Silicon (Si) | 1.00 max | - |
| Phosphorus (P) | 0.040 max | - |
| Sulphur (S) | 0.030 max | - |
| Nickel (Ni) | 0.75 max | Residual |
| Iron (Fe) | Balance | Matrix |
Note Single figures are maximum limits unless shown as a range. Always confirm against the heat-specific EN 10204 3.1 certificate supplied with your order.
Mechanical properties
| Tensile strength, min (annealed) | 655 MPa / 95 ksi |
|---|---|
| 0.2 % yield strength, min (annealed) | 345 MPa / 50 ksi |
| Elongation in 2 in, min (annealed) | 20 % |
| Typical hardness, hardened and tempered | 48 - 54 HRC |
| Maximum recommended service temperature | About 650 °C |
Warning Values depend on product form, section thickness and heat treatment. Larger sections generally achieve lower strength than thin product; always design against the applicable code allowable stress rather than these figures.
Physical properties
| Density | 7.75 g/cm³ (0.280 lb/in³) |
|---|---|
| Melting range | 1450 - 1510 °C (2640 - 2750 °F) |
| Modulus of elasticity | 200 GPa (29.0 x 10⁶ psi) |
| Thermal conductivity at 20 °C | 24.9 W/m·K |
| Mean coefficient of thermal expansion, 20-100 °C | 10.3 µm/m·°C |
| Specific heat capacity | 460 J/kg·K |
Specifications by product form
| Forgings & flanges | ASTM A182 F6a family or to order (UNS S42000) |
|---|---|
| Butt weld fittings | To order |
| Seamless pipe & tube | ASTM A268 TP420 or to order |
| Plate / sheet / strip | ASTM A240 420 · ASME SA-240 |
| Bar / rod | ASTM A276 / A479 |
| Welding consumables | ER420, with preheat and immediate temper |
| UNS / EN / China | UNS S42000 · W. Nr. 1.4021 / 1.4028 · GB 20Cr13 |
Product forms available
Hangbo supplies this grade in the following forms. Sizes outside the listed range can often be produced to order.
- Forged flanges blanks and finished flanges to ASME B16.5, B16.47 Series A/B and B16.36
- Butt weld elbows, tees, reducers, caps and stub ends to ASME B16.9 and MSS SP-43
- Seamless pipe and tube to the applicable ASTM / ASME pipe specification
- Forged rings, discs and hubs machined to your drawing
Typical applications
- Cutlery, surgical and dental instruments
- Valve seats, gates and pump wear rings
- Plastic injection moulds and die casting tooling
- Shafts, spindles and springs needing high hardness
Welding, forming and machining
- Welding
- Preheat to 200 - 300 °C and temper straight after welding. Hardened 420 should never be fusion welded without a full re-heat treatment.
- Heat treatment
- Anneal at 840 - 900 °C and furnace cool, or austenitise at 980 - 1035 °C, oil or air quench, then temper at 150 - 400 °C for cutting hardness.
- Hot and cold forming
- Hot work in the range stated by the mill for this grade, then re-solution or re-age before final machining so that the delivered condition matches the certificate.
- Machining
- Machine with sharp carbide or high-speed steel tooling, positive rake, constant feed and ample coolant. Never dwell - the surface work-hardens quickly.
Buy Stainless 420 from Hangbo
Material is supplied with full heat-number traceability, solution annealing or ageing performed under calibrated furnace control, and an EN 10204 3.1 certificate covering chemical analysis, mechanical properties, heat treatment records and the agreed NDT scope. Positive material identification and third party inspection and test reports from SGS are available for critical service.