Heat treatment is a dark art. What works for one heat treater may not work for the other. Also, heat treaters are somewhat reluctant to share their secret sau

Heat treatment is a dark art. What works for one heat treater may not work for the other. Also, heat treaters are somewhat reluctant to share their secret sauce with customers. General hardening is no problem. The challenge is when a company needs a very specific hardness. There is a fair amount of trial and error with the heat treater (at least at first) before they get it right.