Microstructure and wear property of surface modification layer produced by laser melt injection WC on Q235 steel

Laser melt injection (LMI) technology has great potential in the field of material surface modification.WC powder was injected into the surface of Q235 steel by LMI process,and the influence of process parameters was studied.The microstructure and composition of the coatings were analyzed by means of SEM,XRD and EDS.Hardness and wear-resistant property of the coatings was measured.The results show that successful LMI layer can be achieved only on the condition that process parameters meet the strict requirements.Through optimizing the process parameters,excellent coatings can be acquired.Microstructure in the coatings is complex,which consist of WC,W₂C,and M₆C (Fe₃W₃C-Fe₄W₂C) phases.The differences of Fe₃W₃C microstructure in the different zones of the coatings are obvious.The compositions of the reaction layers around particles and dendrite precipitation carbides in the upper coating are both Fe₃W₃C.The average hardness of LMI layer is about four times of that of Q235 steel.The friction coefficient of LMI layer is not over one quarter of that of the substrate,which indicates wear resistance of coatings enhanced sharply.