13-8 Mo stainless is hardened by heating solution-treated material, Condition A, to a temperature of 950°F to 1150°F for 4 hours, then air cooling. The various heat treatments are as follows (note all times are "at temperature"):
Condition A(Solution treated or Annealed) Heat at 1700°F +/-15°F (time dependent on section size), cool to below 60°F so that the material is completely transformed to martensite. Normally, 1 hour hold at temperature is suggested. Section under 36 sq. inches can be quenched in a suitable liquid quenchant; larger sections should be air cooled.