Heat Treatment is the whole process of hardening & tempering the steel after manufacture of the blade.

I heat blades in a programmable Paragon furnace which is highly accurate and produces repeatable and verifiable results; the blades are heated to their hardening temperature then quenched in oil, water or air as necessary. I frequently use differential heat treatment to provide for hard edge and a supporting, more flexible spine.

Hardening is followed by multiple tempering cycles with intermediate deep freezing to ensure that the blade has the correct grain structure and hardness, typically 60-65 Rockwell C dependent on the specific needs.