Assessment of Strength and Toughness of Alloyed Tool Steel for Cold Metal Forming under Combined Stress

摘要

To assess the strength and the toughness of an alloyed tool steel (JISSKDll) for cold metal forming，q uasi-static combined stress tests undertensile and torsional stresses are carried out by using the hollowspecimens varied with the hardness. As the measures of the strength andthe toughness， the equivalent yield stress and the absorptive energyestimated by the equivalent stress-strain relation are used respectively.From the relations between the absorptive energy and the hardness ofthe tool steels， three kinds of regions which correspond to the ductilefracture， brittle fracture and transition were c1early recognized.By introducing anisotropic parameter r value for the anisotropic yieldfunction proposed by R. Hill，the relations between tensile yield stress andtorsional yield stress， that is， the yield curves are a fairly goodapproximation.The hardness and optimum condition of heat treatment in the case ofwhich the alloyed tool steel，SKDll is used practically are also discussed.