5 for 5.......aarggghhhh!!!!

jdm61

jdm61

itinerant metal pounder
Joined
Aug 12, 2005
Messages
47,357
I heat treated 5 blades today and they all warped to some degree. I have never every freakin' blade warp before, so I thought about what I did differently and came up with this. Because I had more blades to do than usual, I had the Paragon heated up and put each knife into the hot oven and let it soak after the oven came back up to temperature. In the past, I have put the knives in a cold, or at most, a slightly warm oven and brought them up to temperature and let them soak for a bit. Anyone else ever have this happen? Any suggestions?
 
This one is easy. Simply re HT your blades and straighten them while still hot during the quench.

In the future, like you said, a more gentle preheat might help, and interrupt your quench around Ms and tweak them back straight while still very hot.

I HT D2 with high thin hollow grinds (down to.010") and pull them from the plates around 400-600 and nudge the tips back in line. It takes very little force, a light nudge with the thumb is all I need while still mostly austenitic.

Martensite takes up more space than austenite. If areas are going through Ms at different times, things can get funky. Slowing down the second half of the quench can help everything catch up.
 
Nathan the Machinist said:
This one is easy. Simply re HT your blades and straighten them while still hot during the quench.

In the future, like you said, a more gentle preheat might help, and interrupt your quench around Ms and tweak them back straight while still very hot.

I HT D2 with high thin hollow grinds (down to.010") and pull them from the plates around 400-600 and nudge the tips back in line. It takes very little force, a light nudge with the thumb is all I need while still mostly austenitic.

Martensite takes up more space than austenite. If areas are going through Ms at different times, things can get funky. Slowing down the second half of the quench can help everything catch up.
Click to expand...
I treid to straighten a couple of them. Too much or warp was in a bad spot. Gotta straighten hot, reanneal and start over. With two of them, the warp was so slight that I couldn't see it with my fuzzy eyesight, but noticed it too late.:D I have a sneaking suspicion that putting them in the hot oven is the cause.
 
this may be a dumb question, so forgive me asking the obvious, when you put them in do you haave them standing up in a rack or laying on their side?

-Page
 
I have had a similar problem with a rack, I think blades heat unevenly since the blades on the outside will get alot of radiant heat from the coils and the walls of the kiln. Starting with a cold or not too hot oven seems to help prevent warping. I had to redo my HT up to 3x on one blade to get it straight, ugly.
 
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