Impact of scrap use on the properties of hot-work tool steels

Scrap is an important raw material applied in the production of tool steels by electric arc furnace metallurgy. Its composition and especially its contents of residual elements can have a crucial influence on the properties of the steels produced. Resuming the results of a former ECSC-sponsored research project, the working properties and the properties important for the use of the steel as a tool were investigated using thirteen heats of hot-work tool steel X38CrMoV 5 1 (material no 1.2343) that contained different contents of the residuals copper, nickel, phosphorus and aluminium. The properties investigated comprised of continuous castability, hot workability as well as mechanical-technological properties at room temperature and at elevated temperature. The elements phosphorus with a content of up to 0,021 mass.-% and aluminium with mass contents of up to 0,025 % were closely associated with a deterioration of ductility and toughness at room temperature as well as at elevated temperature. Likewise hot workability was impaired. Copper mass contents of up to 0,38 % reduced the time-dependent properties and ductility. Of the residuals investigated, nickel with a mass content of up to 0,49 % was the least harmful. Under consideration of the custom-designed requirements on hot-work tool steel maximum upper limits are suggested for the elements investigated.