Heat Treating a Revolver

Short version: probably not. Almost certainly not.

One could, theoretically, weld the crack up then re-heat treat and harden the frame. But you'd want to know a whole bunch of specifics about the alloy DW used, and how hard they got it. Then I'd want to have a hardness test done to see how close I got.*

*I guess that also depends on where the crack is. There are less critical area's of the frame.

Heating the frame and hammering the crack shut will not repair the crack. The crack needs to be fused by some welding method. However, the heat input from welding will distort the frame to some degree. You will also need to know the frame composition to select the welding process and filler metal, if a filler metal is used. For me, repairing the frame would not be worth the time nor the expense.

NOOOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!!!!!!!!

The cracked frame is junk.
Denis

Where is the crack? It might not matter at all* and the gun can safely be fired with the crack. But as far as welding it or heating it white hot and hammer welding it, that would definitely be a bad idea; don't try it!

*I recall a poster who reported a cracked frame on his brand new S&W. The crack ran from in front of the hammer, down back of the recoil shield and around under the cylinder and down in front of the trigger.

Jim

A good TIG welder could likely fix the crack without over heating the rest of the frame

In a word...no. please don't blow yourself up.
Keep that extra gun basically as a parts kit. It is nothing more at this point. I would even go as far as to spraypaint it red to distinguish it from a serviceable gun.

From my understanding about welding it COULD be welded. But it's not an easy one pass over the crack sort of thing. It would need to be V'ed out and multiple passes used with the correct filler rod to fill in the crack. Along the way the frame would need to have the weld peened to correct for shrinkage by cold forming the weldment out to the right size.

Then when it's all finished you need to get the repair machined back down to the right shape. Only then is it ready for a proper heat treating of the whole frame. And not just the hardening. The tempering back to the right spring like qualities needs to be done correctly to avoid further warping. If it's even possible.

Your knife making has given you part of the equipment and skill set. I'm in the same boat. But when I looked further into all this stuff for heat treating I quickly learned that it gets a lot more specialized in a hurry when looking beyond simple knife making or machining cutters from drill rod like I typically do.

All of this is a costly and time consuming repair which will likely cost more to have done than the frame is worth.

It would need to be V'ed out and multiple passes used with the correct filler rod to fill in the crack.

Click to expand...

That would mean it's one HUGE "crack"

What you're describing sounds more like joining a complete seperation

Cracks in something like a gun frame don't just appear on the surface. By the time it cracks it WILL be deep. And the weld will only penetrate about 1/16 to 3/32 inch. So that's why it would need to be V'd out so it can be fully welded from very near or at the apex of the crack and then back out to the surface. Otherwise the weld is just a bandaid over the remaining separation inside the frame.

If the crack is so shallow that it could be filled in one pass then it suggests a crack which is so narrow that it would only be found with a dye penetrant test or with some other NDT method. Anything I've ever seen in metal of any sort which is visible to the naked eye is deep enough that it would not be fully repaired with a single pass.

"In addition to my regular job, I also make knives. I have plenty of experience in heat-treating them properly. I heat them up in my kiln until they will no longer stick to a magnet, then I plunge them into oil. None of my knives has ever broken (as far as I know). I use high carbon 1040, or 440C stainless steel for the blades."



At what temperature do you draw the blades back to? Do you temper "Draw back" the blades after heat treating. What is your final RC scale hardness on the blades? If the blades are not drawn back they will be to brittle and prone to cracking.

I have heat treated several Ruger frames . They are made from 4140 and you
want them to Rockwell 43 on the "C" scale. As I remember and this has been
40 years ago, I put the frame in the oven at 1500 degrees for a hour then into
oil. After cooling back into the oven at 400 degrees to draw it back to Rockwell
hardness of 43. Hope this helps.

I did some welding in a past life. In my experience a gun frame is so small and the metal so thin that the mere act of striking an arc would blow away half of the gun. And I wouldn't let a torch near a gun.

striking an arc would blow away half of the gun

Click to expand...

You're describing "stick welding"
TIG is much more precise and easy to control

Marv, it sounds like all the welding you did was with big bad welders, heavier sticks and bad torches.

I think you'd be amazed at what can be done even with stick welding with the right electrode choice in the smaller 1/16 sizes. And then TIG raises the bar on the possibilities to a whole other level. Check out You Tube with the search terms "tig pop cans" to see what I mean. It's an eye opener that'll make welding a gun's frame seem pretty simple by comparison.

There's also one from Larry Potterfield where he TIG's some build up on a Parker shotgun's barrel hook that again shows how TIG can be a gunsmith's friend.

JB Weld!!!

Unless you know the chemical composition of the frame, have access to the heat treat specs for the frame and can duplicate the process to get it the same and have a way to keep the frame from warping while welding, I think you are peeing in the wind on this one. Heat treating a knife is a little different in that it doesn't have to contain thousands of pounds of pressure repetitively.

If the crack is in the frame, and not in the area under the barrel (where revolvers typically crack), a repair is possible. First, do a Rockwell hardness test to get the basic frame hardness, then weld, remachine, and heat treat. Rule of thumb is 1500 degrees F for 1 hr. per inch or less of material thickness, oil or brine quench, and draw at 300 to 400 degrees F and cool to final hardness. GTAW (TiG) is the only welding process practical, and it would be best to anneal the frame before welding to minimize warping. It is absolutely essential that you know the alloy the frame is made from so you can specify the proper filler material (autogenous welding is not a likely candidate); what the heat tratment and stress relief regimens are, and verify the weld integrity through X-ray to get a successful repair. Oh, yes - a refinish will also be required. Like I said, the repair is technically possible. Possible; yes... feasible; without specialized tools and knowledge, not likely.

Adding to JD's post is that when heat related warping needs to be minimized it's also normal to pre-heat the item so that the heat of welding isn't adding as much and it can all cool and shrink together. The shrinking of the weld that causes the warping comes from it being so localized and because it melts into the base metal and then shrinks as it freezes again. Pre-heating both aids in a little more penetration as well as expanding the frame before the welding is done so the freezing of the weld pool isn't as big a shock and it can then all cool and shrink more evenly.