DIY Case hardening

[flatwins]

I have an old SxS shotgun that was probably originally case hardened but if so all the color is worn off. I'd like to try to do a little at-home case hardening if possible. Can't remember if it can be done with a propane torch or an oxy\acet rig. Anyone tried to make purdy colors on metal?

 

[shortgrass]

Ya', I put 'pretty colors' on metal, but I use the bone charcoal method.

 

[Ozark Tracker]

I had to use oxy\acet to get any color on a thin piece of metal, so I'm assuming you'll need it for a gun too, never have tried it on a gun, i'd play around with some metal and see what I could do.

 

[flatwins]

Ozark-

That's just what I'm looking for. I remember reading about the torch technique for another project that I have yet to finish. It a fuel-rich oxy flame then quench it in oil, locking the carbon in.

Shortgrass- The leather and\or bone method sounds pretty cool too. That's probably the "original" method.

thanks guys!

 

[Ozark Tracker]

I think when I was playing around with that, I found that different oils produced different colors and brightness of colors, I don't remember what I was using on that metal, but I tried it with spray on WD 40, cutting oil and motor oil,

I think I'd get some thicker metal and try a few combinations.

 

[BrandonM]

Be sure to get some before and after photos. I would love to see the finished result. Good luck man.

 

[Fyrtwuck]

Would this heat treatment affect the hardness of the receiver and cause a safety problem?

 

[Spiff]

Would this heat treatment affect the hardness of the receiver and cause a safety problem?

Case hardening really only affects the very outside of the metal....but that's definitely something to be concerned about. But being that this is something low pressure like a shotgun, it might be ok.

I think the OP definitely might want to ask some more questions about this.

 

[flatwins]

These are good points and hopefully some of the 'smiths here will have some input. As I understand it, case hardening has been around for centuries as a way to put a hardness on the surface of otherwise soft steel. I'm no expert but I don't see it distorting the overall receiver itself. It looks like I'm going to end up with a couple of extra receivers as I have a lead on a "project" gun of the same type as mine and it has a spare receiver that could be sacrificed in the name of research. ;-)

This is a Stevens 311 shotgun and the project one I'm looking at has the Sears' house brand receiver as a spare in addition to the actual Stevens unit.

 

[shortgrass]

Any time you heat a piece of metal be it with a oxy/accet. torch or a heat treating oven and quench it you will have distortion to some degree. The hotter the material being quenched the more possibility of distoration. Many variablies come into play here. A thin piece will warp more than a piece with more mass. (your 311's won't warp much) By using a 'fuel rich' flame and light grease ( try some Rig Gun Grease) you will be introducing carbon into the surface of the metal. Quenching is when hardness is realized, the higher the temp when quenched the harder the surface. (low carbon steel being case hardened needs to be quenched at or above 1333 deg. f. to realize hardness) The bone char process I use is , basicly, one of the 'old fashoned' ways of case hardening. It was and is done to case harden the steel the colors being a by product of the hardening process. Requires more than most have for tools, crucibles, heat treat oven large enough for crucible (mine is 13"h x 12"w x 18"d) , a minimum 35 gal. quenching barrel, a source for the proper bone charcoal, and a way to handle a 1333 deg. crucible to get it contents into the quench and retrieve those parts. Torch hardening can produce some colors for your project. Nice you have at least one expendible receiver to experiment with. There are few set rules and experimentation is the best way to see what works and what doesn't! (the best quenching will be with oil for flame hardening, I'd have a bucket of at least 4gal. ,used motor oil will work as good as any and be the cheapest. have a fire extingusher handy and when you dunk the part in the oil swish it around until it is cool enough to handle with your hands)