Jacob Palmer

Thermal Cycling/Normalizing Questions

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I'm working on a short-ish blade right now, and I'm trying to make my chances of a successful heat treat as high as possible. I know all most of the basics and some of the chemistry, but I still have one question: What is the best method of thermal cycling/normalizing? I know that you should get it to crit temp then let it cool to black, or room temp, but how many times should I do this? What I've been doing is heating it up to crit, letting it cool to black (I do that three times in a row) then I heat it a little bit above crit and let it cool to room temp, then I heat treat. It's worked so far, but y'all probably have more experience than me. 

 

Thanks,

              Jacob

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Depends on the alloy!  For instance normalizing is not suggested for S-1. Not telling us the alloy means anything we suggest will just be a random guess.

(The *best* way would be to send it out and have it done professionally; I won't discuss perfectly good ways as you wanted the BEST and did not supply any details to narrow it down!)

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The best method for a DYIer is the one you can achieve good results with, repeatedly. :D

I usually do three normalizing cycles as a rule of thumb. I place my work pieces on a a wire rack so they cool more evenly. I've placed a few pieces on concrete before just to see what would happen and they warped pretty badly on me during the heat treat, so my recommendation is a wire rack of some sort. I also let my pieces soak in the forge the duration depends on the thickness and what the piece is for. I don't think there is a best way to do it yourself, if you want perfection.

 

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The bladesmiths and metallurgists can correct me if I'm wrong on this, but I think one of the ideas behind the triple normalization is to do it at a slightly lower temperature each time. As I understand it, this makes new grains forming at the boundaries between the old grains, which results in a finer grain structure; heating to a higher temperature creates a new, coarser grain structure, so having your second or third normalization at a higher temperature undoes the good work of the earlier cycle(s).

Is that correct?

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When doing the three normalizing cycles should I let it cool to room temp or to black each time? I'm mostly looking for a standard rule of thumb sort of thing. I just want to make the chances of a good heat treat as high as I can doing it myself, without going to some crazy measures.

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cool to below conversion, if you let it get cooler you are just allowing  for more grain growth

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1 hour ago, Steve Sells said:

cool to below conversion, if you let it get cooler you are just allowing  for more grain growth

By below conversion you mean below critical temperature, right? For most 10x steel the crit is around 1500f, so just under that? Or lower?

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