Bending Bronze

[Seagreen]

I've aquired a bargain on ebay, but it needs "adjusting" a bit. OK, no gloating, please.
These are bronze castings, but one is slightly bent. Is it possible to gently heat and apply pressure to straighten them? Can this be done in the garage or should I get an expert to do it?

 

[earlybird]

Castings aren't noted for ductility, and "bronze" covers a variety of alloys, so bending is bound to have an element of risk. However, if it's bent one way, there's a reasonable hope it will bend back again. First of all, carefully examine the bend. If there is any sign of cracking I'd not be keen on trying to bend it back. Where it's bent, the alloy will be slightly work hardened, so it might be best to first anneal it by heating to 400 deg C or so for a minute or two,( less than red-heat). That done, I think it would then be OK to bend cold, provided only slight bending was involved.
No money-back guarantee mind you!!

 

[NickiCrutchfield]

After annealing copper in metalwork in school we immediately quenched it. Would this practice apply to bronze also?

 

[vyv_cox]

After annealing copper in metalwork in school we immediately quenched it. Would this practice apply to bronze also?

Entirely dependent upon exactly which 'bronze' we are talking about. Genuine tin bronzes are quite ductile, as are the ones that are modified 70/30 brasses. 60/40 brasses, on the other hand, are rather brittle. In the case of the former it should be possible to do it cold. Not too sure about the 60/40 but can look it up if you confirm it to be this type.

 

[KristiferColumbus]

I've aquired a bargain on ebay, but it needs "adjusting" a bit. OK, no gloating, please.
These are bronze castings, but one is slightly bent. Is it possible to gently heat and apply pressure to straighten them? Can this be done in the garage or should I get an expert to do it?

I would heat it to cherry red & then straiten it out.Let it cool for a couple of minutes then quench it in water to give it reasonable strength.
Don't quote me on it though because I could'nt find the exact procedure in my reference book.

 

[earlybird]

After annealing copper in metalwork in school we immediately quenched it. Would this practice apply to bronze also?

Quenching copper has several effects; it saves time, it removes some of the thin oxide film that forms during heating and it provides interest for schoolboys. It has no effect on the final condition. Much the same applies to most common "bronzes" AFAIK.

I would be wary of heating to cherry-red if you don't know what the alloy is, that might be within 150deg. of a typical melting point. It could be OK, but some can be very weak at around that temperature. Over-do it at your peril! If you must heat, I would go for very dull red at the most.

 

[Keith 66]

Be very careful, heating red hot & quenching may make the part go crystalline & useless, some bronzes can be annealed or hot forged others cannot, without knowing what its made of you run the risk of ruining it. If its a small bernd try bending it back cold, but watch for cracking.

 

[Seagreen]

Be very careful, heating red hot & quenching may make the part go crystalline & useless, some bronzes can be annealed or hot forged others cannot, without knowing what its made of you run the risk of ruining it. If its a small bernd try bending it back cold, but watch for cracking.

There's a small casting fault, so I'm wary of bending it cold. I had it in mind to heat it to a very dull red at the bend and let it cool without quenching. I thought that at those temps the structure would be pliable enough to bend safely without the metal becoming fuid enough to re-crystallise. How do I find out what type of alloy it is by just looking at it?

BTW, these are Highfield levers (not Davey pattern) and also have the remnants of chroming on them. They wouldn't come under horrible strain as the bend is in the lifting handle part and not the main body.

 

[Ubergeekian]

Be very careful, heating red hot & quenching may make the part go crystalline & useless, some bronzes can be annealed or hot forged others cannot, without knowing what its made of you run the risk of ruining it. If its a small bernd try bending it back cold, but watch for cracking.

Er-hem (polite cough). All solid metals are crystalline. All that changes is the size and type of crystals.

 

[vyv_cox]

There's a small casting fault, so I'm wary of bending it cold. I had it in mind to heat it to a very dull red at the bend and let it cool without quenching. I thought that at those temps the structure would be pliable enough to bend safely without the metal becoming fuid enough to re-crystallise. How do I find out what type of alloy it is by just looking at it?

BTW, these are Highfield levers (not Davey pattern) and also have the remnants of chroming on them. They wouldn't come under horrible strain as the bend is in the lifting handle part and not the main body.

Seems very unlikely to me that a highfield lever would be cast. Much more likely to be a forging and made from a true tin-bronze. Need more information, can you post a photo?