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Crusader68: "CCH finish on a part made from 4140?"

Color case hardening is not done only to create a "finish;" it, foremost, is done to impart a hard surface to the steel, to protect it from scratching, denting, etc., which also happens to make it less susceptible to corrosion. It does little or nothing to give steel more tinsel strength overall, The colors are just a byproduct of the process, (it is thought by the authorities to have happened only by accident, while performing early work on developing the whole process). The colors fade over time, and are eventually eliminated over time, due to sunlight beating on surface, and more significantly due to rubbing (friction) of any kind from gun case, hands, etc. Thus, cch surfaces should always be protected with a coating, such as clear lacquer. Color case hardening of firearms, is generally limited only to parts made of mild steel, low carbon steels, because they color case easily and well. 4140, and many other similar steels used for making gun parts, is generally NOT color case hardened, because the process alters, to some degree, the normally superior tensile strength, and other desirable characteristics of these steels, negatively altering their normally desirable characteristics for a best gun part steel. How do I know this? In tech. college, gunsmithing class, I took color case hardening, learning the process, and also learned the methods and techniques from a highly skilled, knowledge gunsmith, who, at one time, worked in engraving and color case hardening with Colt. Also, I tried to learn all I could from the work done by Oscar Gaddy, when he was alive.

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