The only references to a C3 stainless that I can find refer to a structural stainless steel which is not heat treatable since its very low in carbon at .015%. You need at least .4% Carbon before a steel is considered martensetic(heat treatable). Structural stainless steels are typically used in the manufacture of stainless sinks, pipes, large storage tanks etc and are high in nickel and chromium, plus some aluminum. Perhaps you're using a different designation for a martensetic steel as manufactured by some different source; manufacturers sometimes devise their own nomenclature,i.e. Buck's 420HC, rather than use standard AISI codes. You'd have to give me the steel composition, if its different than what I've found before I can say much more. BTW, many of the cheap knives on the market today are made of various grades of 420 stainless, most of which are also very low carbon. While structural steels can't be heat treated, they do respond, a little, to work hardening. That means they can hold an edge for a bit. A lpt of scalpels are made from 420 since it's cheap and they are a one time use, throw away item. Also, having your blade, of the proper steel, heattreated isn't all that expensive an operation. D'Holder HT's mine and charges me anywhere from $10.00 for a couple of blades, or less for the more blades I send. Paul Bos also runs a HT service aimed at knifemakers, and he is also reasonable. There are others.
