... designhigh hardenability, high toughness, and fine-grained.The use of Electric arc furnace (EAF+ refiningLF+ VacuumVD + Vacuum Electro-slag ... heat deformation, and in air-quenching , the tendency of the appearing of iron oxide skin is small. In 500 tempering, it will appear ... tempering process should avoid around 500 .According to the use of molds, the tempering temperature should be in the range ...