Persistent cracks

Persistent cracks

Postby Joe D » Sat Mar 11, 2017 3:19 pm

I cast a shibuichi ingot that was about 40% silver a while ago. I did what Ford instructed and upset the edge by quite a bit and then began to forge down. I annealed liberally during this whole process. Everything was fine until I got to about 3/8 of an inch when cracks formed in two spots. In my last ingot I filled the little crack out and kept moving. filing has not worked on both cracks and they reappear no matter how far I file (you can see how much material I have removed). I don’t know what to do and fear that I might just make it worse.

Should I Solder the cracks like ford suggested here: viewtopic.php?f=13&t=1455&p=16036&hilit=hira#p16036

Should I just trim the outside? I would hate to waste the material.

Or should I keep forging and let the cracks come to an equilibrium.

Any advice would be greatly appreciated.

Cracks: http://imgur.com/a/fPev4
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Re: Persistent cracks

Postby Chris A » Sat Mar 11, 2017 9:30 pm

My opinion, for what it's worth, is solder the cracks now as they can only get bigger.
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Re: Persistent cracks

Postby ps_bond » Sun Mar 12, 2017 10:48 am

For non-water cast billets I always scalp (filing the surface back) before working them down to help reduce the chance of this happening; since you've already filed back and your billet is still suffering with crack propagation then, as with Chris, I'd solder. I often flow solder across the edges of mokume gane billets to help avoid delamination starting; the solder is removed later on as part of the general wastage of the billet.
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Re: Persistent cracks

Postby Ford » Sun Mar 12, 2017 7:20 pm

Joe

how did you anneal?
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Re: Persistent cracks

Postby Joe D » Sun Mar 12, 2017 8:26 pm

Thank you so much for the advice. I will try to solder it when I get a chance.

Ford: I heat it to a dull red before i see silver bubble to the surface. I usually just leave it to cool and do something else but sometimes i quench it immediately and it goes in the Sparex.
Is quenching bad?
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Re: Persistent cracks

Postby Ford » Sun Mar 12, 2017 9:14 pm

you should quench at a good red heat. Slow cooling essentially hardens the alloy.

And the most effective way to stop a crack growing is to drill a little hole at the end.
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Re: Persistent cracks

Postby Joe D » Wed Mar 15, 2017 1:12 pm

Sorry for the late response.

I feel really dumb. I hadn't noticed a difference under the hammer when I let the ingot air harden.
The tip about drilling a hole is really useful and it appears to work.

I was able to solder one of the cracks but the other just wasn't holding so I had to prune it.

Thank you again for the great advice.
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