doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com cyanide case hardening of shotgun parts

dont know about this method of heat treating, except that i have heard it is quite dangerous...any info re the process would be in appreciated...

and does anybody currently do this kind of work?

I�m not aware of any that do. More importantly why? Flame hardening yields a much harder, deeper and durable case with none of the inherent hazards of using sodium cyanide.

Dave

Bobby Tyler of Tyler Gun Works does it.

dtm: flame hardening? tell us more about that...

was wondering what current manufacturers of shotguns, such as csmc,beretta and the turks, are doing to case harden shotgun parts...are any of them using a cyanide process...

Flame hardening is just that, a high temp flame is used to heat the steel then quenched in water or oil. Which liquid used for quenching used is determined by the carbon content of the steel and the desired hardness. The flame is either an oxyacetylene or oxyhydrogen one resulting in a deep hard martesite layer over a soft inner core. The flame can be applied via a single head torch or a custom design predicated on the shape of the object to be hardened.
Cyanide hardening produces a shallow hardness layer of .5 to 5 mils in depth with a hardness of 50 to 65 HRC. Pack hardening is the type used which we are generally familiar yields a case depth of 5 to 60 mils with a hardness of 55 to 65 HRC. Flame hardening yields a case depth of .5 to 8 mils with a hardness range of 45 to 70 HRC.
Large parts such a some gears and machine toolways are flame hardened.

dtm: be aware that flame hardening, aka torching of shotgun receiver parts and forends, is frowned upon by some members of this forum...with that said, do you have an opinion you would express here?

Yes I aware that flame hardening is frowned upon by some here on this forum as is cyaniding. If used correctly, however its results are superior to cyanide hardening.
If one were restoring a firearm, then there is but one choice and that would be to anneal the parts to remove hardness and temper and use the methods employed at the time they were manufactured, ie bone and charcoal pack hardening. Bear in mind the coloration of the steel is secondary to the purpose of hardening it. A welcome side effect if you will.
If one is attempting not to restore but to place back in service a tired old worn piece, flame hardening would be preferable to cyaniding. It is safer and yield better results.

This thread is stupider than Wonko�s hockey thread, but not quite as stupid as the Old Bed thread.


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Why is this a stupid discussion? I realize I am new here but I am not new to metal working. The information I provided came right out of an ASM white paper on hardening processes.