Böhler (or Boehler) W303 ISODISC is a hot work tool steel with outstanding hot tensile properties, high retention of hardness, good toughness, and resistance to heat checking. W303 ISODISC is a special grade with improved homogeneity and increased toughness. This datasheet provides information on composition, physical properties, and elasticity. It also includes information on forming and heat treating. Filing Code: TS-724. Producer or source: Böhler Edelstahl GmbH.