After reading the "hardening/general heat treating" sticky I still have a question...

I'm no newbie when it comes to metalurgy, hardening, tempering, material dynamics etc, but I do have a small question about hardening receivers. I have access to a heat treating oven, and I'm trying to get the quench process nailed down before I ruin a part.

I'm worried about warping the receiver during the quench. Is there a specefic order of operations I should follow? What I'm asking here is should I start with one end of the receiver in the quenchant, submerge the part, then work my way to the other side? Should I place the reciever in a basket, letting the bottom of the receiver meet the quenchant first, then sinking the rest of receiver?

Help walk me through this. Thanks!

The thin gauge receiver will easily warp. Usually to oven treat a whole receiver a steel jig inside the receiver is required. Even then many receivers will still warp. I think one of the big makers said they have 2 - 5 percent of their receivers warp. It might have been a higher number than that and I have no idea how they jig the receivers.

There is another way besides in an oven but requires super special huge equipment. If you are building flats there are some people that designed their own jigs and there are some pics. Still count on a few "test" receivers that won't survive. I would think jig the receiver and use a coat hanger type wire for the quench. The steel must still be above 1250 F when it gets quenched. Not easy to do with sheet steel 1.0 mm thick.

That's what I was figuring. While I've heard of people "spot" hardening with an oxy./acet. torch, it just seems like such an un-even heat would cause more problems than heating and quenching the entire receiver. If this works well, I'll probably go that route for my first receiver, then make some sort of fixture to hold receivers in allignment for future builds.

This looks like the best way so far.

http://www.ar15.com/forums/topic.html?b=4&f=51&t=110499