Are strawed parts
 

case hardened? Is this what the yellow color comes from?
Steve

Although both processes employ heat, they are not the same thing. Strawing is produced by simply heating the parts at about 300 degrees for a certain amount of time. Case hardening employs other steps/additives.

Thanx.
Steve

Add a little more temp, and the parts go purple, then light blue, then dark blue. Then dingy gray.