Heat Treating AK Receivers - Metalurgist?
This question may also apply in general to fabricating an AK receiver from a flat.
I have a B-West AK47S, Norinco parts manufactured on a US made B-West receiver prior to the 1989 ban. As some of you may know, the B-West receivers were not heat treated. It's not that they were heat treated improperly, they were not heat treated at all.
The problem is potential elongation of the receiver holes. I have been told it is possible to heat treat around these holes the same way the Chinese did. The whole receiver was not heat treated on Chinese AKs, just the holes and ejector. Apparently they heated the area around the holes and ejector and quenched the area to harden it.
This gun doesn't appear to have been fired very much, and I'd like to heat treat the receiver before doing anything with it. Do any of you have good information, or a web site address on the proper temperatures to use?
To err is human, to moo is bovine.
I have a B-West AK47S, Norinco parts manufactured on a US made B-West receiver prior to the 1989 ban. As some of you may know, the B-West receivers were not heat treated. It's not that they were heat treated improperly, they were not heat treated at all.
The problem is potential elongation of the receiver holes. I have been told it is possible to heat treat around these holes the same way the Chinese did. The whole receiver was not heat treated on Chinese AKs, just the holes and ejector. Apparently they heated the area around the holes and ejector and quenched the area to harden it.
This gun doesn't appear to have been fired very much, and I'd like to heat treat the receiver before doing anything with it. Do any of you have good information, or a web site address on the proper temperatures to use?
To err is human, to moo is bovine.
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Potential problem? Do you know, 100% the AISI designation of the steel the reciever is made from (1010,1040)Tool steel? (A2 D2 O1)?
If not then I'd say don'y try to cure a problem that does not yet exist! You will also need to know the critical temperature for heat treatment of this particular steel, as well as what to quench in after heating. Quenching in the wrong media can cause annealing, or it could cause the steel to be as hard as glass! After heat treat you will also need to temper the steel! One last though on heatreating a small area. Metal thats heated will expand and warp! You might end up with a heat treated piece of junk!0 -
If you were a sporting fellow you could remove the four rivets holding in the barrel extension and remove the barrel plus extension.
Heat the front 2 3/4" of the receiver (3 3/4" to include the ejector)
to a bright red then quench in brine. Test with a file to see if it has hardened then temper in molten lead at about 600f and quench in water.
It might work or it might warp or remain soft.0 -
v35, Maybe you don't understand. The front of the receiver is never heat treated. It is the area around the trigger/hammer holes the Chinese heat treat, as well as the ejector, not the front of the receiver. They torch heat treat these localized areas.
To err is human, to moo is bovine.0 -
GIM had this pretty much covered. It matters not that the receiver has never been heat treated. What matters is if the steel used is heat treatable. If it is, you need to know just what steel you are dealing with. There are many heat treatable steels and many processes. Localized heat treating is commonly done. It can be done without heating the entire receiver. First thing though is to find out what this receiver is made of.
cbxjeffIt's too late for me, save yourself.0 -
Gunisme is right. It would be hard to heat treat any metal if you don't know what steel it is. They all use different heats and quench techniques. If it's a medium carbon, you would want to oil quench, not brine quinch. Your best chance would be to mask everywhere except the holes, and case harden it.
The NRA is on our side!0 -
I thought Boeboe was concerned with the highly stressed holes holding the locking lugs. This is an area reported to give trouble after much use. As far as the trigger and hammer pin holes wearing goes, I wouldnt worry about doing anything about it.
The steel is likely to be relatively low in carbon to take the small radii 90 degree bends and the embossed side features hence my recommendation for a severe quench from recrystallization temperature.
Yes, its nice to have the SAE or AISI material designation but obtaining it isn't likely. That's why I prefaced my comments as being a sporting proposition. If it's hardenable it should respond.
Heating the receiver to case harden it will kill off the hardness of the ejector which is spot welded to the receiver and also the barrel extension that is riveted to the front of the receiver.
If I were to make one I'd start with 1mm 4140 aircraft quality sheet
in dead soft condition.0 -
v35,
I agree with you on a good grade of 4140, but I'll bet it's low carbon 1018 or 8620. In that case, case hardening is all you can do to it.
The NRA is on our side!0 -
Guys, if it's 1018 used for formability, you can forget hardening. One thing you might do, if you really want to attack this, is not bother with hardening. A couple of other options might be (and hey, I don't even own one of these) is to look into enlarging the holes in question and pressing in a bushing that would handle the radial load. The other thing would be to ream the holes slightly and flame spray a hard coating. I don't know how much this rifle is worth, but it might be more cost effective to just buy 2 or 3!
cbxjeffIt's too late for me, save yourself.0 -
You guys have some good thoughts.
I had considered something along the lines of brazing re-inforcement pads around the holes and drilling/reaming to the proper size. It seems that relying on twice the thickness of soft material, with the loads carried over the area of the braze would be a good option. I might have to have extra length pins made up for the extra thickness, but that wouldn't be too difficult. But then, I'd still have the soft ejector.
As far as the value of the gun and the option of buying two or three, the thing is, this is a true pre 1989 ban AK47S with the folding stock, bayonet, and threaded barrel. But this is a bottom of the line for AK style firearms, even though it is pre-ban. Unfortunately, as they came from the factory, the life expectancy of these firearms before deformation became a problem was around 2000 rounds due to the soft metal. I'd be surprised if this one I have has had over 500 rounds through it. If it were a Polytech or Norinco I might have some qualms about destroying the originality of the firearm, but to me, given what it is, I'd just like to turn it into a nice and reliable (but very evil looking) plinker.
Keep in mind, this process is something that third world firearms factories could handle. It's probably not too sophisicated. I would imagine some Chinese slave laborer with a torch and quenching bucket could handle the process. It can't be that sophisicated...
To err is human, to moo is bovine.
Edited by - boeboe on 11/16/2002 23:02:440 -
Ok, were talking practical solutions. You have several options; the easiest is to ream the holes oversize using #70 and # 75 reamers and
make oversize pins, the second would be to rivet doubler plates on the sides, the third to braze up the holes and build up pads, the fourth to MIG weld up the holes using a harder steel.
The ejector can be wrapped with a wet rag if you're going to braze or weld.
Consideration should be given to making a drilling fixture before you start welding or covering up holes.
I would give up the idea of heat treatment because my money says the receiver is not a heat treatable grade. A Rockwell hardness test would probably show it to be on the upper B scale.
If the ejector isn't beat up or burred it's probably a heat treated part.0 -
Guys, 1018 CAN be case hardened. Remember, case hardining is the process of COOKING carbon into steel instead of cooking carbon out of steel.
The NRA is on our side!0
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