Chemical Composition (%)
| Sn | 6.0~7.0 |
|---|---|
| P | 0.26~0.40 |
| Cu | Balance |
Mechanical & Physical Properties
| Tensile strength | ≥410 MPa (hard temper) |
|---|---|
| Elongation | ≥3% (hard temper) |
| Hardness | ≈180-220 HV |
| Density | 8.8 g/cm³ |
Typical Applications
Grade Overview
QSn6.5-0.4 is a wrought tin phosphor bronze with 6.0-7.0% tin and 0.26-0.40% phosphorus, corresponding to UNS C51900. Phosphorus deoxidises the melt and raises strength and elasticity; the alloy is a standard spring and contact material, combining fatigue resistance with good electrical conductivity and corrosion resistance. In the hard temper it reaches at least 410 MPa tensile strength and 3% elongation, with hardness around 180-220 HV.
Selecting QSn6.5-0.4
Choose QSn6.5-0.4 for springs, elastic elements, electrical connectors and terminals, wear plates and sliding strips, vibration reeds and diaphragms, and precision instrument parts. It is a wrought grade supplied as strip, sheet, wire and bar. Where higher conductivity is needed, a copper-beryllium or a pure copper grade is better; where higher strength is needed, QSn7-0.2 carries more tin.
Working with QSn6.5-0.4
The alloy is supplied in tempers from soft to hard and is formed, stamped or bent in the temper selected for the part. It work-hardens readily, so anneal between severe forming operations. Machining is moderate; use sharp tooling. Soldering and brazing are good. Avoid overheating during forming or joining, which softens the spring temper.
Frequently asked questions about QSn6.5-0.4
What does 6.5-0.4 mean?
About 6.5% tin and 0.4% phosphorus, with copper as the balance.
Is it the same as C51900?
It corresponds closely to UNS C51900 phosphor bronze. Confirm the temper and standard on the certificate.
Can it be used for current-carrying springs?
Yes. It is a common contact and spring material, with conductivity lower than pure copper but adequate for many connector duties.
Data compiled from current standards; for selection reference only. Ordering is subject to the standard and the mill certificate. Data source: Shenyang Yuheng Metal Manufacturing Co., Ltd. — yuhengmetal.com.
Related wrought copper alloy grades
QSn6.5-0.1 · QSn7-0.2 · QSn4-3 | All 52 grades in the library