Microstructure stability and high temperature wear behavior of an austenite aging steel coating by laser cladding

Abstract

An austenite aging steel coating was prepared by laser cladding on H13 steel in order to overcome the poor thermal stability and high-temperature wear resistance of the latter. The microstructure, element and phase distribution of the austenite aging steel coating were investigated by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM), and recrystallization were determined by quasi-in-situ EBSD. High temperature wear tests for the austenite aging steel coating and H13 steel were performed on a high temperature pin-on-disk friction and wear tester, and their wear resistance was comparatively evaluated. The austenite aging steel coating was dominated by γ-Fe as matrix phase, while micrometer-grade NiAl and nano-scale Ni3Ti existed as strengthening phases. These fine particles existing in the grain boundary of the coating could effectively improve the recrystallization resistance and thermal stability, which was confirmed by quasi-in-situ EBSD and thermal stability tests. Owing to such superior thermal stability, oxidative mild wear prevailed for the austenite aging steel coating in most of sliding conditions except for 600 °C and 150 N, where a mild-to-severe wear transition of oxidative wear occurred. In particular, the plastic extrusion wear of H13 steel at 600 °C and 150 N was impeded due to the existence of laser-cladded austenite aging steel coating.