The most economic and most frequently used production route in powder technology is uniaxial die pressing of the powder at ambient temperature and subsequent sintering of the powder compact at high temperature. Many materials are processed via the powder route, for example sintered steels, ceramics, hard metals and cermets, refractory metals, and certain polymers. In this project only sintered steels were considered. The main problem in the production of complex sinter metal parts is the occurrence of cracks that develop during pressing and ejection. Hence the primary goal of the present simulation effort was to investigate the conditions for crack formation and to formulate appropriate constitutive equations describing cracking as a consequence of strain localization. Another challenge for the powder metal industry is the increasing demand for geometrical accuracy. A controlling factor for the achievable accuracy is the elastic spring-back of the pressed part during unloading and ejec tion. Hence the nonlinear and anisotropic response during unloading was measured and included in the constitutive model.
