Keep sorted in your mind that hardening and coloring are differing processes. You can harden without coloring, color without hardening, and harden with coloring. Also, note that differing steel alloys react somewhat differently to the various hardening/coloring processes. Further note that low carbon steel is sufficiently strong (assuming adequate section thicknesses) without case hardening (the only hardening available for low carbon). The case is for surface wear reduction. Higher carbon steel alloys (which will through harden) are more likely (within my knowledge) to be colored separate from hardening. Witness the W-W M-21; the original plan was a case colored finish on a through hardened receiver. Said plan didn't work out satisfactorily, so they through hardened and blued.
Cyanide case hardened steel may or may not have increased surface hardness; I can't say. However, I am sure it is not to be worried about other than as a scientific fact. Aesthetics are, of course, your individual call.
DDA
Last edited by Rocketman; 08/07/15 04:20 PM.
