- Grade / Alloy
- 303Cu
- EN / W.Nr.
- 1.4570X6CrNiCuS18-9-2
- AISI / SAE
- —
- UNS
- S30331
- Other names
- 303Cu
- Family
- Austenitic
Chemical composition
Chemical composition
Composition limitsComposition limits for long products within EN 10088-3:2014. Special cases allowing a 1.0% Cu maximum for cold-work-hardening or extrusion products are outside the general range shown here.
| Element | Content (% by mass) |
|---|---|
| CCarbon | ≤ 0.08 |
| SiSilicon | ≤ 1 |
| MnManganese | ≤ 2 |
| PPhosphorus | ≤ 0.045 |
| SSulfur | 0.15–0.35 |
| NNitrogen | ≤ 0.1 |
| CrChromium | 17–19 |
| NiNickel | 8–10 |
| CuCopper | 1.4–1.8 |
| MoMolybdenum | ≤ 0.6 |
Values describe the grade, not the analysis of a specific batch. The applicable product specification and material certificate determine acceptance. A dash does not mean zero.
Properties of 303Cu
1.4570 is related to the austenitic 303 family but is distinguished by its copper content. The combination of sulfur and copper is intended for parts where machinability is important. Small fittings, bushes and turned components in different diameters are familiar examples. The name 303Cu should therefore not be read as merely another spelling of 303.
Comparison with 303 and 1.4598
General 303 / 1.4305 is a sulfur-bearing chromium-nickel stainless steel. Grade 1.4570 also has a defined copper range. Grade 1.4598 contains molybdenum as well and is closer to the 316 family. Their shared machining focus does not make these three grades identical. Greater corrosion demands call for more than machinability alone.
Does 303Cu always describe the same product?
Producer catalogues may use 303Cu, 303Cu+ or similar names for products with different copper ranges. This record follows 1.4570 / X6CrNiCuS18-9-2. Weldability and resistance to severe corrosion are not its principal selection advantages. This distinction explains why a readily machinable material cannot replace every stainless component.
Mechanical properties of solution-annealed long products
Values are given for the stated +AT long-product conditions and sections up to 160 mm under EN 10088-3:2014. Bright or cold-worked bar values are considered separately. Elongation is for longitudinal testing.
| Property | Value |
|---|---|
| Tensile strength Rm | 500–710 MPa |
| Proof strength Rp0.2 | ≥ 185 MPa |
| Elongation A | ≥ 35% |
Typical application areas
Turned fittings, bushes and small machine parts.
Product and cutting options
Relevant product forms for this material are listed below. Availability varies with grade and dimensions.