Tin Bronze
C90300 — Tin Bronze (88-8-0-4)
An unleaded tin bronze with good strength, pressure tightness and corrosion resistance for valve bodies, bushings and gears.
Grade overview
C90300, sometimes referred to as “G bronze” or 88-8-0-4, is a classic unleaded tin bronze. It has a dense, fine-grained structure and is valued for pressure tightness, strength and good resistance to corrosion in fresh and salt water.
The absence of lead makes it harder to machine than leaded bronzes but more suitable where lead content or very high pressure tightness matters. It is a common choice for bushings, gears and valve components in steam and water service.
Alloy family and identification
Cast copper-tin-zinc alloy, UNS C90300, commonly referred to as 88-8-0-4 tin bronze (Cu-Sn-Pb-Zn). Contains only trace lead.
| Item | Detail |
|---|---|
| UNS designation | C90300 |
| Common name | Tin Bronze (88-8-0-4) |
| Alloy family | Tin Bronze |
| Type | Cast copper-tin-zinc alloy |
Typical composition
| Element | Nominal limit, wt % |
|---|---|
| Copper (Cu) | 86.0 – 89.0 |
| Tin (Sn) | 7.5 – 9.0 |
| Zinc (Zn) | 3.0 – 5.0 |
| Lead (Pb) | 0.30 max |
| Nickel (Ni, incl. Co) | 1.0 max |
| Iron (Fe) | 0.20 max |
| Antimony (Sb) | 0.20 max |
| Phosphorus (P) | 0.05 max |
| Sulfur (S) | 0.05 max |
Reference data only – typical or nominal values from published specifications, not a guarantee of supplied material. Confirm against the current edition of the applicable specification, the product form and condition, and the material test certificate. Technical review by the company is required before publication or reliance.
Typical mechanical properties
Mechanical property values are intentionally not published here. They vary with specification, product form, size and temper or condition and will be added only once the governing specification and condition are confirmed. Request the applicable specification or test certificate with your inquiry.
Physical properties
Physical properties (density, thermal and electrical data) are not listed until verified against an authoritative datasheet. Contact us for current reference data.
Corrosion and wear considerations
Resists corrosion in fresh water, steam and many salt-water conditions. Pressure tightness is a key feature of tin bronzes. Not suitable for oxidising acids or ammonia-bearing media.
Machinability and fabrication
Moderate machinability – lower than leaded bearing bronzes. Reduced lead helps where lead-limited alloys are preferred. Suitable for soldering and brazing; welding requires procedure control.
Common industrial applications
- Valve bodies and fittings (design dependent)
- Bushings and bearings
- Gears and worm wheels
- Pump components
- Marine hardware in compatible service
Examples only. Suitability must be confirmed for the actual operating environment.
Available product forms
Sizes, tolerances and stock are not published and must be confirmed with the company.
Relevant products
Standards and specifications
- ASTM B584 – sand castings
- ASTM B505/B505M – continuous castings
Verify against the current edition and the exact product form before specifying.
Certification and inspection options
Material test certificates, chemical analysis, dimensional reports and third-party inspection can be requested with your inquiry. What can be supplied for C90300 is confirmed with the company for each order; no certificate is implied by this page.
Related grades
Frequently asked questions
Is C90300 lead-free?
It is a low-lead alloy (lead limited to a trace level in the specification) but is not marketed here as meeting any drinking-water standard. Lead-restricted applications should be reviewed against the applicable regulation.
How does C90300 differ from C90500?
C90500 has a higher tin range, giving a harder and somewhat stronger alloy.
Need C90300 in a specific form?
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