Martensitic stainless steel
- AISI 430, 440
"Martensitic stainless steel is a specific type of stainless steel alloy.
Martensitic stainless steels can be high or low-carbon steels built around the Type 410 composition of iron, 12% chromium, and up to 1.2% carbon.They are usually tempered and hardened.
Tempered martensite gives steel good hardness and high toughness; used largely for medical tools (scalpels, razors and internal clamps).Untempered martensite is low in toughness and therefore brittle". (From Wikipedia)