| The laser ladding stainless steel coatings and stainless steel/Al2O3composite coatings are made on surface of45#steel using CO2laser. The physical and mechanical properties which include macroscopic morphology, phase composition, microstructure, microhardness, wear and corrosion resistance are studied.The process parameters possess great effect on the quality of the coating. The parameters of the experiment are proved by experiments and theoretical analysis. It is clear that the effect of scanning speed on the macroscopic morphology and cross-sectional microstructure of stainless steel coating is great when other parameters are constant.The stainless steel powder consists of austenite phase by XRD analysis, stainless steel coating is composed of ferrite and austenite phase.The electrochemical analysis shows that corrosion potential of stainless steel coating is much lower than45#steel substrate, while the current is higher than those of stainless steel coating, so the stainless steel coating possess excellent corrosion resistance. This conclusion is also verified by corrosion resistance test.15%FeCh solution is used to test the corrosion resistance of the coatings. Weight of laser cladding coating does not change, but that of the substrate reduces seriously. There are many holes on the surface of substrate. So stainless steel coatings have better corrosion resistance than the substrate.Microhardness of the stainless steel coating is close to that of substrate, the hardness of composite coating is higher than the substrate. But hardness of heat affected zone is much higher than cladding coatings and substrate because of emergence of martensite. Fiction and wear tests of stainless steel/Al2O3composite coating show that wear resistance is significantly improved since Al2O3powder is added. Fiction coefficient of coating is lower than substrate. |
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