The Gun Counter

I bought a couple of un coated AR500 plates. Seeing as they were uncoated I decided to hit them with some k-phos then some black gunkote 2400. This of course requires a one hour bake time at 400 degrees.

I have been doing some reading about tempering of steel when making knives. So now I am wondering, did I just reduce the hardness of my AR500 by setting them in my toaster oven for an hour at 400 degrees, then air cooling?

wouldn't that be GREAT.

I did a quick search and didn't find the temperatures used to temper AR550. That said, I would guess that you probably did change the steel by putting it in an oven at 400 degrees for an hour. How much of a change is the question.

I doubt you can undo what has been done so set it up at 100 or 200 yards and hit it with a few rounds and see if it pits/dents etc. then report back.

A link from people smarter than me: link

Maybe my degree in engineering shouldn't be used as a coaster...

I like the file test that he suggests. Try a file on an untreated plate, and then one that you've stuck in the EasyBake.

Thanks guys.

These are plates that are going to be shot at as part of a test. I really doubt I took them down below brinell 400. My research says I retempered it which should on work to make it less brittle at a slight cost in hardness.

I don't have a non-cooked one to compare, but after the shoot I will be getting some replacements, so I can do the file thing then. I am buying some 50,55,60,65 rockwell files for just this kind of testing on knives. I may have to go down to 45 as well. 50 Rock is roughly 500 Brinell, 45 is roughly 430.

Huh. Did you notice whether the metal changed color? Blue, straw, anything like that?

ETA: Ah, my bad.

If you could change the steel's hardness by baking to cure Gunkote, you wouldn't want to bake steel firearms to cure Gunkote, either. Most powder coating is cured at about 400F also... I have sometimes seen people say not to powder coat vehicle springs for fear of damaging the temper. Which sounds reasonable, until you consider that brand new coil springs are almost universally supplied with a powder coat finish.

Aluminum, on the other hand... You will fuck up the temper of heat treated aluminum by baking at 400F.

Netpackrat wrote:Aluminum, on the other hand... You will fuck up the temper of heat treated aluminum by baking at 400F.

NEVER EVER EVER powder coat/bake aluminum scuba tanks. Because the next time they are filled, they may burst, severely injuring or killing the person filling them. There have been several instances of this.

It depends entirely on what process the parts were heat treated originally. If they were austempered or anything similar (any process that resulted in a phase change of the material) then 400 shouldn't touch it. For less severe processes 400 could definitely effect the hardness.

Vonz90 wrote:It depends entirely on what process the parts were heat treated originally. If they were austempered or anything similar (any process that resulted in a phase change of the material) then 400 shouldn't touch it. For less severe processes 400 could definitely effect the hardness.

I have no idea of the original process. I do know that I will shoot them and they will work or they won't. For this purpose, they should still work fine as I doubt anything I am going to hit them with, would be stopped by 1/4" ar350.

@ NPR. I had that thought too, but was not sure as I don't know that much about the tempering/ heat treating process and how one process might vary from another of any of the other variables I might not even be aware of.