Authors:
Annalisa Fortini (1), Ottavia Vezzani (1), Michele Gragnanini (1), Gian Luca Garagnani (1), Mattia Merlin (1)
1- University of Ferrara, Department of Engineering, Italy
Abstract:
Powder metallurgy (PM) steels containing diffusion-bonded Ni are characterized by microstructural inhomogeneities related to the lack of Ni diffusion during sintering. As a result of sinter-hardening treatment a martensitic microstructure with Ni-rich austenite areas is obtained. Aiming at homogenizing the Ni distribution by diffusion, in the present study two different post-sintering treatments were performed, consisting in a vacuum quenching at 900 °C for 1 h and 3 h, respectively, followed by inert gas cooling. Microstructural evolution was investigated through hardness tests, optical and scanning electron microscopy, coupled with image analysis techniques. The mechanical properties of sinter-hardened and heat-treated samples were evaluated through Charpy impact, tensile and pin-on-disk tribological tests. The main effect on material properties was given by austenite content reduction and the resulting formation of Ni-rich martensite.
DOI:
https://doi.org/10.59499/EP246281385
