Microstructure and Impact Properties of Low Alloy Sintered Steels

摘要

This paper discusses the influence of the micro-structure on the Charpy impact properties of some low alloy sintered steels. The materials were produced by using four different Cr, Mo and Ni prealloyed powders, and by adding Cu by diffusion bonding. The carbon content was varied between 0.05% and 0.4%. Three different densities, between 6.8g/cm_3 and 7.4g/cm_3 were obtained, and sintering was carried out at 1120°C and 1250°C. The as sintered microstructure depends on how the alloying elements influence the transformations of austenite on cooling. These transformations were investigated by dilatometry. Instrumented Charpy tests were carried and the characteristic parameters of the impact curve were determined: yield load, maximum load, deflection and the total adsorbed energy. These parameters are mostly correlated with microhardness, since all the materials have an elastoplastic behavior.