The formation of internal cracks in as-cast billet is mainly attributed to the stress and strain states near the solidifying front. This study investigates the effect of chamfer configuration of as-cast billet on the maximal principal stress and the tensile stress during soft reduction process. The LIT and ZDT of GCr15 bearing steel are calculated by the solidification phase transformation model. What’s more, the 3D finite element models is established to investigate stress and strain states in the brittle temperature range. The relationships between chamfer angle and maximal principal stress, internal crack, as well as equivalent plastic strain are analyzed. Numerical results reveal that a chamfer configuration of as-cast billet is much more effective than a rectangular one on decreasing the risk of internal cracks.

The present research is focused on the characterization of the composites from Al2O3-Cu-Ni system. Two methods of ceramic-metal composite forming were applied: uniaxial powder pressing and Pulse Plasma Sintering (PPS). To obtain the samples the powder mixtures containing 85 vol.% of Al2O3 and 15 vol.% of metal powders were used. Influence of the sintering process on microstructure and mechanical properties of the two series of the composites was analyzed in detail. The selected physical properties of samples were characterized by Archimedes immersion method. Vickers hardness and the fracture toughness of the composites was determined as well. The microstructure of the composites was characterized by XRD, SEM, EDX. Fractography investigation was carried out as well. Independently on composite production method Al2O3, Cu, Ni, and CuNi phases were revealed. Fractography investigation results revealed different character of fracture in dependence of fabrication method. Pulse Plasma Sintered samples were characterized by higher crack resistance and higher Vickers hardness in comparison to the specimens manufactured by uniaxial pressing.