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I have access to large amount of lead and I was wondering if, when melted, could it reach temps to heat treat with, to reduce scale? would the lead mix with the steel when its that hot? way off base?

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Lead won't alloy with steel at tempering temperatures, and it did used to be used to temper springs, but if you get it over about 800 degrees F it has a nasty tendency to vaporize. That means you'd be breathing lead vapor, which as far as I know is still considered to be a generally bad idea. Temper your springs in it by all means, but don't use it as a substitute for high-temp salt for hardening.

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Look at the stickies at the top of this subforum. Then check out Darren Ellis's selections. He'll even sell you the stainless tubes and such you will need.

 

I'd love to have some nice sword-lenght salt tanks, but that kind of cash is not in my realm of possibilities. :(

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Actually, there's a phenomenon called liquid metal embrittlement that I believe can cause problems even at tempering temps. Basically, liquid metal gets into the steel grains and promotes cracks. (I think this is why tin isn't used as a high temp medium for hardening, even though it would otherwise be quite suitable and doesn't raise the toxicity issues that lead does.) I'm pretty sure Scott MacKenzie has mentioned this at least once before; maybe he can step in and clarify.

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I've got to agree with Alan - lead is a nasty metal with significant fume issues. Lead has also been used for tempering for files - back in 89 I worked for Airco Industrial Gases and we were approached by Heller files in southeastern Ohio about replacing their lead heat treating facility with nitrogen based atmospheres. They needed to stop using lead due to environmental concerns as well as health related issues for their workers. If memory serves, they were using lead baths both to austenitize and temper their files. Not certain if they're still in business or not, but they competed with Nicholson and made a decent file.

 

During my tenure with Airco any workplace that dealt with lead usually had to test their workers regularly for lead in their blood after it reached a certain level, they had to go on a chelation treatment to reduce it and work in areas with less exposure to lead fumes. The lead in the blood occurred, even with the use of chemical respirators.

 

Liquid metal embrittlement - part of it is exposure time and temperature, part of it is the type of metal - I don't remember any major issues with lead for heat treating times for objects of a file thickness. Going on memory, mercury was a major bad actor for liquid metal embrittlement. I'm not certain about tin.

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I read that lead bath were used to austenize razor blades, so I suppose that it worked also on thin sections. It's a pity that it's vapour causes saturnism.

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