[epicfail48]

Originally Posted by samuraistuart

epicfail48:

Post quench but pre temper, the matrix is already "martensite", it becomes "tempered martensite" after the temper.

Depending on the steel and heat treatment, there will be some small (or large God forbid) amount of retained austenite after the quench. This retained austenite will get converted to martensite during the temper, usually only at temperatures at or above 400F. The higher the alloying, and the higher the austentizing temperature, the more retained austenite will be present. And it is a good idea to get rid of that retained austenite as much as possible before tempering, ie sub zero or cryo. Most of the low alloy carbon steels, using the low aus temps, have very very little RA to deal with.

Dang it, I knew I had a few of those -ites mixed up!