Relationship between Mechanical Properties and Nature of Fracture Surface of Powder Steels under High-Temperature Tension

Results of research on high-temperature tension for powder steels by the Swedish company Höganäs are analyzed. Morphological differences in the structure through the cross-section of a cylindrical specimen, which is conventionally divided into central and peripheral areas, are revealed. Microstructural analysis and fractographic study of the fracture surface are performed in each area. These studies provide identification of areas of fractures having different relief in intercrystalline shears and their extent, which indicates the presence of areas on the surface of interparticle contact with different degrees of completion of interparticle fusion. It is shown that plastic flow is accompanied by formation of peripheral region material whose structure and properties depend on the degree of deformation and production conditions. As the peripheral region develops material strength properties decrease after reaching a critical amount of transverse flow. Mechanical properties of specimens prepared from the highest quality materials are studied in detail at high temperature. This provides a complete picture of the occurrence of microcracks and the potential for using the material under actual conditions.