Type 420 is a high-chromium, martensitic stainless steel known for its excellent hardening capability and good corrosion resistance. It can be hardened through heat treatment to achieve high strength and wear resistance, making it ideal for applications such as knives, surgical instruments, pump shafts, and valves. While its machinability is lower compared to free-machining grades like 416, 420 stainless steel offers improved corrosion resistance due to its lower sulfur content.

420 stainless steel retains magnetic properties in all conditions and can achieve significant hardness through quenching and tempering. In the annealed state, it exhibits good ductility, but after hardening, it can reach very high hardness levels, making it suitable for high-wear applications. However, due to its higher carbon content, it is not recommended for use in high-pressure environments or applications requiring extreme corrosion resistance.