CuSn4
CW450KLow-tin phosphor bronze — the standard connector and spring material in the CuSn series. 4% Sn gives good spring properties, corrosion resistance, and electrical conductivity. Better electrical conductivity than higher-Sn bronzes. Used for connectors, contact springs, switch parts, and precision bellows. ≈ UNS C51000.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | UNS | USA | UNS C51000 (Phosphor Bronze A) | C51000 | REF |
| 🇪🇺 | EN | Europe | CuSn4 | CW450K | 100% |
Sources: ASTM B103, EN 1652
Chemical composition comparison (wt%)
Side-by-side: CuSn4 (EN) (EN 1652) vs CuSn4 (EN) (EN 1652)
| Element | CuSn4 (EN) | CuSn4 (EN) | Overlap |
|---|---|---|---|
| P | 0.01–0.4% | 0.01–0.4% | OK |
| Cu | — | — | — |
| Sn | 3.5–4.5% | 3.5–4.5% | OK |
| Zn | 0–0.1% | 0–0.1% | OK |
| Pb | 0–0.02% | 0–0.02% | OK |
Mechanical properties
Annealed
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 330–400 | MPa |
| Yield Strength | 120–200 | MPa |
| Elongation | 40–55 | % |
| Hardness HB | 55–85 | HB |
| Elastic Modulus | ≥ 110 | GPa |
| Density | ≥ 8.89 | g/cm3 |
H04 Half Hard
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 450–560 | MPa |
| Yield Strength | 400–520 | MPa |
| Elongation | 10–25 | % |
Related materials
CuZn37
2.0321Lead-free alpha/alpha+beta brass (63% Cu, 37% Zn). Compromise between cold formability (CuZn35) and hot formability (CuZn40). The most widely used unleaded brass. Used for cartridge cases, radiator cores, lamp components, plumbing fixtures, and decorative hardware.
CuZn36Pb3
CW603NFree-cutting leaded brass — the benchmark for non-ferrous machinability (rated 100%). Lead particles act as chip breakers for excellent surface finish. Used for screw machine parts, fittings, valves, watch components, precision mechanics, and electrical connectors. Old DIN number 2.0375.
CuSn6
CW452KPhosphor bronze with 6% tin — better cold formability than CuSn8 at slightly lower strength. Excellent spring properties and fatigue resistance. Used for electrical connectors, spring contacts, switch parts, bellows, bourdon tubes, and precision springs.
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