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Brian Madigan

AISI 1084 carbon steel

34 posts in this topic

1 hour ago, Alan Longmire said:

All steels benefit from slow air cooling after the tempering step.  It may only be a miniscule benefit, but it's better than quenching.

I'd just amend this to say most steels.  There are some that definitely need a water quench after a temper.  Generally these are not blade steels though.  

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Okay, that's what I thought but as I've been watching more and more Youtube videos and such I'd seen a lot quenched. Just wanted to make sure I wasn't missing something. Thanks!

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5 hours ago, Alan Longmire said:

All steels benefit from slow air cooling after the tempering step.  It may only be a miniscule benefit, but it's better than quenching.

Alan--I used to  think the same way but I've been told by those who know much more than I  that it really doesn't make any difference.  I've  not done any testing to know one way or  the other.

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Duly noted!  You and Jerrod certainly know more than I do.B)

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For the record, my take on quenching after a temper is this:

1)  Avoid the blue brittle range as much as possible.  If you have martensite it should spend as little time as possible between 500-900 F (the exact edges of this range are under debate and are likely alloy dependent).  So 4325 quenched then tempered at 1150F must be quenched.  Anything tempered at 450 or below doesn't need it.  Anything that doesn't have martensite (like 1010), isn't affected by this rule.  

2)  Other than following the above guideline, quenching or not after a temper cycle is all about convenience.  Letting it slow cool will continue the tempering (depending on thermal mass and temperature this may not be significant), quenching will end it right away.  Blades at temperatures under 500 F are good either way.  

Somewhere I'm sure there is an odd alloy that doesn't fit into these, but I haven't played with it yet.  

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One advantage that I  have  used a  time  or two is when the blade does a  slight bend during tempering.  By running water over the outside or convex side of  the bend, I have been able  to  straighten it but this is seldom relevant.

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Gary, that is a great idea!  I seem to always get a slight bend when quenching.  Is that something that can be attempted after the first tempering cycle, or do you wait until at least the second?

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On 2/15/2017 at 10:10 AM, Alan Longmire said:

All steels benefit from slow air cooling after the tempering step.  It may only be a miniscule benefit, but it's better than quenching.

It also has the potential to cause warping and cracks from what I've heard. I haven't experienced it myself, but I also don't quench them again after temper.

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It's interesting that Stacey, the moderator at bladeforum, suggested quenching after tempering or between tempers.  I pressed him on this, and it was said there is a miniscule advantage to it, though things got very technical at that point and I pressed no further.

I started quenching between tempering cycles, and the one difference I've been able to discern is it is quicker... Pull the blade out of the oven, quench, stick it right back in for another round.  Other than that, I can't see any difference, good or bad.

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