[TheForge] looking for"real" bronze

[Peter Fels & Phoebe Palmer]

Acknowledging that my alloy ID is often guessed at or 2nd hand,
and that i'm self taught...and about to doubt a near deity...grin...
I've had a terrible time trying to forge architectural bronze...it cracks easily, has a narrow working temperature range and attempts at repair turn ugly. Machines nicely though.
Al  bronze is buttery in it's temperature range, but unforgiving out of it.
Silicon bronze alloys vary, but trend to be kinda sticky, plastic and more forgiving.
The more zinc in an alloy, i found, the narrower the forging temperature range. 
Also the more zinc, the less successive working heats it would tolerate, it seemed.
"Naval" bronze alloys and" everdure" i played with were quite forgeable.
I speculate that when Jim says forgeable, he is thinking in terms of rollers and presses and excellent temperature control.
For me, it's hammer , anvil, treadle hammer tooling, gas forge or torch more likely and sloppy eyeball temperature estimates.

On Feb 17, 2013, at 6:11 PM, James Binnion wrote:

Historically bronze was a copper tin alloy but also had lots of other things in it as well due to less the materials and processes available. Today a copper alloy that does not have zinc or nickel as the second significant metal in the alloy is a bronze.

The closest thing you can buy to that real bronze is what is called phosphor bronze it is 94.8% copper, 5% tin and a tiny amount .2% of phosphorous to deoxidize the metal. The trade number for this material is C5100 or C510. The stuff is tough to work and not a good choice for hot working, in fact no copper tin alloy will be a good hot work alloy.

The best forging alloy is called Architectural Bronze (C3850) which is actually a brass as it has zinc as the second greatest metal in the alloy after copper. 57% Cu, 40% Zn, 3% Pb just don't weld it as the lead makes it a poor choice for welding both from a health and performance aspect.

A reasonable compromise alloy is Commercial Bronze (C2200) which has reasonably good hot work properties and can be TIG welded but it is again a brass called bronze at 90% Cu, 10% Zn



James Binnion
jbin at well.com



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