O1 steel also is called DIN 1.2510 and JIS SKS3 steel. High content for manganese, chromium and tungsten in 1.2510 steel composition, that could increase the hardening ability. Then the steel does not need to undergo water quenching. After oil cooling and quenching, the hardness could reach 62HRC. O1 tool steel round bar sheet plate was used widely as a cold work mold steel. It is a great material for the blade, metal molds and etc.