Microstructure and performance of Fe-Cr-Ti-C plasma coatings

Fe-based alloy coatings, with and without adding titanium (keeping other powder ingredients constant), were produced on Q235 steel substrate by plasma cladding process with high-energy plasma jet as the heat source. The microstructure, phase composition and microhardness of the coatings were investigated by optical microscope (OM),scanning electron microscopy (SEM),X-ray diffraction (XRD),electron probe microanalysis (EPMA) and microhardness tester,respectively. The results showed that the grain of the Fe-based coating containing Ti was obviously finer than that without Ti,and more band-like crystals formed in the coatings containing Ti. However, with the increase of Ti content in the coating,the hard phase (Cr,Fe)₇C₃ in the eutectic increased gradually and restrained the precipitation of carbides in the coating,consequently,the average and maximum microhardness of the cladding coating decreased.