How to prevent 3/32" 1084 from warping during quench?

[cotdt]

I got about 1mm of blade warp during the quench, not throw-away-the-blade bad but it's noticeable. How do I correct the warp? Also, any advice for preventing warp next time?

 

[69_knives]

Easiest way is to do it right after the quench when the blade is still hot, with gloved hands. I've done some with a plastic 'dead blow' hammer on a rubber-over-steel surface.

Also you can make a couple straightening jaws for a vise out of hardwood, see if this ascii drawing works:

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two smooth arcing pieces of hardwood on one side and one arc on the other side that presses the blade between the two arcs on the other side.

Try to do that when the blade is still warm from tempering.

 

[cotdt]

Thanks for the response, 69_knives. I know that the blade can be straightened while still warm from the quench, but I didn't notice the warp at the time.

Now the blade is fully tempered. Would your vise idea still work? Should I warm it up in the oven again?

 

[Nathan the Machinist]

Cotdt,

Ideally you straighten it before the blade is hard. If you pull the blade from the oil during the quench while it is 400-500 degrees it will still be fairly soft and will respond to hand tweaks (no hammer, just gloved hands). If you pull the blade out and the oil quickly vaporizes you're too hot. If it stays wet and barely makes a wisp, you're too late. It probably takes 6-10 seconds.

Otherwise, your best bet is to straighten it directly from full tempering temp using a jig like 69 is talking about.

If it is high hardness (over 60) you might regret attempting to straight it.

Things to do to prevent warping include a stress relieve by soaking at 1200 and cooling (and straightening) before hardening, and good agitation during the quench to reduce stable vapor pockets.

Kevin goes into this in some of his stickies.

 

[AcridSaint]

I would anneal it, straighten it and try again (after normalizing). I've had some blades return the warp after straightening. In the state that you are in, you've basically got to bend the blade, which is introducing a new dynamic that's not worth all of the hassle in my opinion.

If it is not too bad and you have enough steel left, you may be able to grind it out.