the service hardness of pre-hardened steel is usually within the range of 30—42HRC, wherein the cutting property is not good under high hardness, pre-hardened steel are mostly manufactured with medium carbon steel as the base, appropriately added with such alloy elements as Cr, Mn, Mo, Ni and V. to solve mechanical cutting difficulty under high hardness, add appropriate amount of S, Ca, and Pb into the steel during smelting to improve the cutting and processing property of steel. Some pre-hardened steels can be applied with nitriding heat treatment after molding to improve the surface hardness and abrasion resistant of molds, on the premises of not reducing matrix intensity.