The tensile properties of a Powder Metallurgy Cu–Mo–Ni diffusion bonded steel sintered at different temperatures

The increase of the sintering temperature from 1120 °C up to 1280 °C of a 0.2%C Cu–Mo–Ni diffusion bonded steels with 6.9 g/cm3 and 7.2 g/cm3 green density slightly increases sintered density and improves the pore morphology. The fraction of the load bearing section increases consequently. Moreover, high sintering temperature enhances the compositional homogeneity of the metallic matrix, and the microstructure evolves from a mixture of ferrite, pearlite, bainite, martensite and Ni-austenite to a bainitic/martensitic microstructure, with a decreasing amount of the Ni-austenite. Tensile strength and ductility increase with the sintering temperature. The paper clearly demonstrates the role of the pore morphology on the mechanical properties that are therefore better correlated to the fraction of the load bearing section than to density. It also highlights that sintering temperature may represent a solution to enhance mechanical properties of porous sintered steels as an alternative to the increase in green density.