420 STAINLESS STEEL BAR

420 is a hardenable martensitic stainless steel that contains at least 12% chromium, just enough to provide corrosion resistance. It has good ductility in the annealed condition but is capable of being hardened to a minimum Rockwell hardness of 50 HRC, the highest hardness of the 12% chromium grades. Due to its hardening characteristics, 420 is not often welded, although it is possible. Martensitic stainless steels are designed for high hardness, sometimes with other properties compromised to some extent. Corrosion resistance is lower than that of ordinary austenitic grades, and its effective operating range is limited by its loss of ductility at sub-zero temperatures and loss of strength due to over-tempering at elevated temperatures. The best corrosion resistance is achieved when the metal is hardened and the surface ground or polished.