quote:

Originally posted by Naphtali:
I have viewed photographs of at least three different case hardening processes: a charcoal gray-ish color case; a mottled brown-ish color that I think was identified as "pack hardening"; and something identified as "chemical case hardening."

1. Please describe differences among them, and other variations if there are any, excluding the obvious difference in appearance.



2. What are the purposes for which the processes are intended? If each process has a different purpose, why?
Purpose 1 - Functional - To create a hard surface with improved wear and friction characteristics. The hard surface, if thick enough, will increase the strength of a component. This case may or may not colored in a pleasing manner. It may be subsequently blued so that you do not notice its presence. Purpose 2 - Some processes these days are primarily decorative and cosmetic. There is no function served by case hardening a Ruger #1 frame. The Ruger frame is a through hardening alloy without any need of case hardening. There is zero benefit gained by color hardening a set of scope rings.


3. These processes appear to be used on frames, locks, receivers, small parts, etc. - but I have not seen a barrel having the process. Why?

There are no surfaces on a barrel that require high surface hardness. The function of a barrel is not improved by such a process and a barrel will most likely be warped by the process.

4. Since most firearms do not have parts processed, there may be liabilities to processing beyond any additional cost. What are liabilities?
Assuming proper design of the firearms components there are no liabilities. Assuming proper process design there are no liabilities. For a market that is not interested in the resulting cosmetics it is only a cost issue. It is an added process that can turn out ugly resulting in reprocessing or scrapping of components.


5. Case hardening does not, I believe, build onto a metal surface. Rather it penetrates the surface to alter metal's surface chemistry. How deeply do different processes penetrate, if each penetrates differently? What problems occur with too little penetration? What problems occur with too much penetration?