CU · copper alloy
Silicon Bronze C65500 (Everdur)
A tough, corrosion-resistant bronze that machines reasonably in the annealed condition and work-hardens quickly. Welds well for a bronze, which is a large part of its appeal.
Quoting this material
- Typical lead time
- 10–18 working days
- Condition
- Annealed or cold worked
- Achievable finish
- Ra 1.6 µm typical · Ra 0.8 µm best
Machined in-house to your drawing: see the precision CNC machining service and the machine and inspection capability it runs on.
Machinability
Our own 1–10 shop ranking, not a published index: 10 is free-cutting brass C360, 1 is Inconel 718. It ranks how a material behaves on the floor - cycle time, chip control and tool life together. Where a published index exists it is quoted in the note.
A tough, corrosion-resistant bronze that machines reasonably in the annealed condition and work-hardens quickly. Welds well for a bronze, which is a large part of its appeal.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Tensile strength | 380–600 | MPa |
| Yield strength (0.2%) | 240–450 | MPa |
| Elongation | 30–50 | % |
| Hardness | 150 | HV |
| Thermal conductivity | 36 | W/m·K |
| Modulus of elasticity | 100 | GPa |
Hardness, tensile and thermal figures are typical published values for the condition stated. Actual mill certificates govern; send the specification with the drawing and we confirm against the certificate before the material is cut.
Condition
Annealed or cold worked
Heat treatment
Not precipitation hardenable; it is a solid-solution alloy. Annealing after cold work is a softening step.
Achievable surface finish
Ra 1.6 µm
Ra 0.8 µm
Takes a good finish and patinates to a stable brown - it is often left bare in architectural and marine work.
Tooling and cutting parameters
Cutting speed
- 120–250 m/min (carbide)
Feed
- 0.10–0.25 mm/rev turning · 0.08–0.18 mm/tooth milling
Tooling
- Sharp uncoated or coated carbide, high positive rake
Coolant
- Flood or mist
Starting points for carbide on a rigid setup, not a guarantee. The right numbers depend on the machine, the toolholder and the fixturing - ask and we will say what we would actually run.
Typical applications
- Marine and architectural hardware
- Pump and valve components
- Chemical process fittings
- Welded bronze fabrications
- Fasteners for corrosive service
DFM notes for this grade
- Its weldability is unusual for a bronze: a fabricated assembly in silicon bronze is a real option rather than a compromise
- Good general corrosion resistance but it is not an aluminium bronze - for high-load bearing service, C954 or C63000 are the right alloys
- It work-hardens quickly, so a heavy finishing pass on a previously machined surface will fight the tool
Questions buyers ask
- Where is silicon bronze used in preference to a stainless?
- Marine and architectural hardware where the colour and a stable patina matter, and where a stainless part would show tea staining. It is also chosen where the part is welded, because it joins far more readily than an aluminium bronze.
- Is it a bearing material?
- Not primarily. It has decent wear resistance and it resists corrosion, but the load capacity is well below an aluminium bronze or a tin bronze. For a bearing, use the bearing alloys; silicon bronze is for corrosion resistance and fabrication.
Grades we would quote instead
C63000 Nickel Aluminium Bronze
4/10The strongest of the standard bronze families: about the cutting speed of a stainless and the tool wear of one too.
C51000 Phosphor Bronze
6/10The spring bronze: good machinability with enough tin to give real strength and fatigue resistance.
C93200 Bearing Bronze
6/10The standard bearing bronze: it machines well, it is soft enough to embed grit, and it runs against a steel shaft without galling.