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Help? heating treating .......

Rob Davis

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I am making a batch of 6 knives.   They are shaped and have an initial grind.   My plan was to to take them all up to magnetic 3 times/air dry then heat quench and temper.   I got half way through cycle 2 and ran out of propane.  Some of you may recall my last question about delay between quench and temper.  I had planned to do all of them tonight.   Do I just start over from the beginning tomorrow (after a half day delay) and heat it 3 times air dry then heat and quench??   Or do I  continue from where I left off?  I don't want to screw up this batch.  

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If you have not quenched any of them, then you can pick up where you left off.  If you have quenched a blade it is best practice to put it into temper for at least one cycle.  Otherwise you risk cracking a blade under the residual stress of the quench.

I don't understand what you mean by "air dry", unless you mean "air cool".  When you take a normalize heat (heating to non-magnetic, more or less) you should then let the blade cool in still air to about 900 F (or where there is no longer any visible color in it).  You don't have to let it cool to ambient, you just need to get under the knee in the curve where martinsite begins to form.



"The worst day smithing is better than the best day working for someone else."


I said that.


If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton


So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.


Grant Sarver

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1 minute ago, Rob Davis said:

Yes, I meant air cool.  Thank you!   As always( for me ) the steel came from old files.   Thanks again!   

Then you want to be about 50-75F above non-magnetic.  For normalizing and for hardening.  You'll be better off not using the magnet and sticking with watching for decalescence and recalescence.  

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