Heat treating Thin Chefs knives

Gliden07

Gliden07

Well-Known Member
Is there a trick to heat treating a thin chefs knife blade?? I was at a well known makers shop and watched him forge a chefs knife. He got the cutting edge less than a 1/16" I asked him how he would heat treat the blade and all he said was "VERY CARFULLY". It was made out of 1084 and was a full tang 2" wide heel. I've never had luck with thin, thin blades, they always seem to warp on me.
 
I make chef knives out of 0.09" AEB-L. Not as thin as your friend's knife but they do frequently warp in HT.
I have had the best luck with two things.
I go from cryo right into the tempering oven, and if there is a warp I clamp the blade to a straight piece of bar stock while tempering.
If the warp is "serious" I overcorrect it with a washer or two at the strategic point.
If it comes out of tempering and is still warped I use my straightening hammer on it, and can almost always fix the problem.
 
Even forging, normalize & anneal, quench and put it in a clamp while it's still warm. Correct slight warps in the temper. Grind out any leftover warpage. Sharpen it, test the edge. Wrap paracord around the handle and call it a 3" utility knife for the shop. :)
 
For the thin stuff I would. You could always quench in oil to black heat then quickly slap it into the plates if just using plates bothers you. I am amazed at how fast big fat aluminum plates alone will quench.
 
Chris Railey said:
For the thin stuff I would. You could always quench in oil to black heat then quickly slap it into the plates if just using plates bothers you. I am amazed at how fast big fat aluminum plates alone will quench.
Click to expand...

And not to be Captain Obvious, but plates work best when you grind post heat treat. Having so much flat surface area in contact with the plates makes for tremendous heat transfer.
 
Only part of my post above was a joke. If you quench to about 400F you can clamp the knife before it cools to straighten it. I use a couple of angles in a vise. Any remaining warp can be fixed in the temper. Even forging (or evened out on the grinder) plus a proper normalize and anneal will solve the vast majority of warping.
 
Don’t grind the bevels until after HT on a stock removal blade. On any forged blade that you have chosen to bevel for some strange reason, stress relief is your friend. :)
 
I've made a lot of kitchen knives from 1/16th 15n20. I do all grinding after heat treat and I also do what others suggest. Once I quench, and the blade is still hot I will clamp them between two 1 inch thick aluminium plates.
 
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