Martensitic stainless steel
Martensitic stainless steel typically contains 12-16% Cr, a low amount of Ni, rarely Mo and a relatively high amount of carbon (C, 0,12-1,2%). It can be hardened by rapid cooling to over 1000 HV and due to the extreme hardness, it is particularly suitable for cutting tools such as surgical equipment and high-quality kitchen knives.
After being hardened, martensitic steel can neither be shaped plastically nor be welded. The steel will lose its hardening if welded or exposed to other heat treatments. The martensitic steels are heavily magnetic and, due to their low Cr contents and high C contents, they generally have poor resistance to corrosion. This is often seen after an expensive kitchen knife has been washed in a dishwasher.
Surgical equipment can be produced by the use of martensitic stainless steel. This gives a high strength but unfortunately a relatively poor resistance to corrosion.