m303BÖHLER M303 is a pre-hardened martensitic chromium steel with very hh toughness, wear resistance and machinability. It is suitable for tools processing corrosive moulding compounds, e.g. PVC, and for food and beverage contact.M303 is a type of mould steel with hh chromium and nickel content. It has hh hardness, strength and corrosion resistance. See its chemical composition, physical and mechanical