Straightening 440C Blade

[Tom Militano]

I just received some knives back from heat treating and the one I least wanted anything to happen to came back warped. It's 440C and has had a cryogenic quench. It was a piece of precision ground stock and I checked it for straightness. I've never had to straighten a blade after heat treating, help!!!
Tom

 

[L6steel]

Hmmmmmmmmmmm, I thought your heat treater was supposed to straighten the blades that needed it.. The only safe way I know of to straighten a blade is with a torch, but that will possibly ruin the heat treat. I know 440c has to get real hot and cool extremely slowly to be annealed, but it still looks like heating it enough to take the warp out would change the hardness. I'd get ahold of the heat treater and ask them about it. Not much help I know, but it's all I can tell you.

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http://www.nebsnow.com/L6steel

 

[Jerry Hossom]

Sorry, but you need to change heat treaters. I suggest sending the blade to another heat treater (Paul Bos is highly recommended). He will need to anneal it and reharden, straightening it after the hardening and before tempering. It's salvageable, but a good heat treater shouldn't let that happen.

Precision grinding isn't going to prevent warping. The hollow or flat grinding you did is what makes it warp, but better heat treaters will straighten the blades before they temper.

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Jerry Hossom
www.hossom.com

 

[george tichbourne]

I just take the blades back to the heat treater and there is usually no problem. Of course there has been only one occasion that I have had to do this so my heat treater must be doing his job properly.


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george
www.tichbourneknives.com
sales@tichbourneknives.com

 

[tom mayo]

i thought tom sent them to paul...the best way is with round rods....put two on one side about two inches out from the high spot, and one on the high spot....preferably in your vise...and very carefully crank down a little past true....the hard part is holding the rods....drill bits will do, but stainess rod is safer, bigger is better up to a point....people who have this problem regularly have fixtures to do what i have described above...like folder makers who put interframes into solid stainless bodies, they ALWAYS warp after the cut...or guys who make integral guard and liner folders, same problem....you can do it...go for it...and if it breaks...send it to jerry, he will use anything to make a knife..even jeep leafsprings.

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http://www.mayoknives.com