Technical overview
Silicon bronzes are copper alloys with about 3–5% silicon. Wrought C65500 (High-Silicon Bronze A, Si 2.8–3.8%) offers high strength with good weldability and resistance to salt water, petrochemicals and paper-industry chemicals. It is used for fasteners, pole-line hardware, chemical equipment and marine hardware.
Cast silicon bronzes such as C87300 and C87600 are used for valve bodies, bearings and engineering castings.
Grades & standards
Grades are distinct materials — properties and uses below apply to the named grade only.
C65500
High-Silicon Bronze A (wrought)
Composition: Si 2.8–3.8%, Mn 0.50–1.3%, Zn ≤ 1.5%, Fe ≤ 0.8%, Ni ≤ 0.6%, Cu remainder
- High strength, weldable
- Salt-water and chemical corrosion resistance
- Fasteners, pole-line hardware, heat-exchanger tubes
Listed specifications: ASTM B98/B98M · ASTM B96/B96M · ASTM B124/B124M · ASTM F467 / F468
C87300
Silicon Bronze (cast)
Composition: Cu ≥ 94.0%, Si 3.5–4.5%, Mn 0.8–1.5%
- Cast components
Listed specifications: ASTM B584 · ASTM B271/B271M
C87600
Copper-silicon alloy (cast)
Composition: Cu ≥ 88.0%, Si 3.5–5.5%, Zn 4.0–7.0%
- Valve bodies and stems, bearings
Listed specifications: ASTM B584 · ASTM B271/B271M
Technical properties
| Property | Value | Applies to | Source |
|---|---|---|---|
| Electrical conductivity | 7% IACS | C65500 | Copper Development Association Inc. |
| Melting range | 971–1027 °C | C65500 | Copper Development Association Inc. |
| Specific gravity | 8.53 | C65500 | Copper Development Association Inc. |
Typical or specified values for the named grade from the cited source. Actual values depend on temper, size and the producing mill — rely on the mill certificate for your lot.
Forms
Typical industry forms for this material. They are not a stock list — form, size and availability are confirmed per enquiry.
- Rod & bar
- Sheet & plate
- Welding wire
- Castings
Applications & industries
- Marine and chemical-plant fasteners
- Pole-line hardware and electrical fittings
- Pump, valve and bearing castings
- Hydraulic-pressure lines and heat-exchanger tubes
Selection notes & limitations
- Low conductivity (~7% IACS for C65500) — not a conductor alloy.
What to specify when requesting a quote
- 1Wrought or cast grade
- 2For welding wire: AWS classification and spool size
- 3Grade and the standard it must conform to (ASTM, EN, IS, UNS or your drawing)
- 4Form and dimensions — thickness or diameter, width, length and tolerances
- 5Approximate quantity, and whether the requirement is one-off or recurring
- 6Intended application, so the grade can be cross-checked before quoting
- 7Documents required — e.g. mill test certificate, chemical analysis, certificate of conformity
- 8Delivery city / site and the date you need material by
Documents buyers may request
Mill test certificate
e.g. EN 10204 type 3.1 inspection certificate, where the producing mill issues one
Chemical analysis report
heat / lot composition against the specified grade
Certificate of conformity
confirming the material meets the ordered standard
Heat / lot traceability
heat numbers marked on material and documents
Dimensional inspection report
for cut-to-size or machined material
Safety Data Sheet (SDS)
especially for lead, beryllium-, cadmium- or lead-bearing products
Which documents can be provided depends on the source mill and is confirmed with each quotation.
Frequently asked questions
Why choose silicon bronze over brass?
Silicon bronze offers higher strength, good weldability and better resistance to salt water and many chemicals — at a higher cost than brass.
Sources & technical references
- C65500 — High-Silicon Bronze A (CDA alloy database) — Copper Development Association Inc. (CDA). Checked 2026-10-14.
- C87300 — Silicon Bronze (cast) (CDA alloy database) — Copper Development Association Inc. (CDA). Checked 2026-10-14.
- C87600 — Copper-Silicon Alloy (cast) (CDA alloy database) — Copper Development Association Inc. (CDA). Checked 2026-10-14.
