How To: Heat treating CPM S35VN

Heat treating CPM S35VN

CPM S35VN is a martensitic stainless steel designed to offer improved toughness over CPM S30V. It is also easier to machine and polish than CPM S30V. Substituting niobium carbides for some of the vanadium carbides makes CPM S35VN about 15-20% tougher than CPM S30V without any loss of wear resistance.

Heat treating S35VN can be done at different levels of complexity. The below is the "ultimate" version from knifsteelnerd.com:

• hold at 2025 F for 15 mins (1107 C)
• plate quench
• liquid nitrogen/cryo treatment for 30+ mins
• temper between 300 - 400 F for 2 hours x 2 (149 C - 204 C)
• (adjust temp for hardness, aim for 60 HRC as a starting point)

A simpler heat treatment recipe that is proven to work but provide a slightly lower HRC:

• hold at 1950 F for 15 mins (1065 C)
• quench in oil
• temper at 400 F (204 C) for 2 hours x 2 for 57-58 HRC