Microstructure And Properties Of Tungsten Carbide Composite Coating On Cast Iron Surface By Laser Cladding

Ductile cast iron,with excellent castability,shock absorption and mechanical properties,is widely used in machinery,metallurgy,mining,petroleum,petrochemical and other fields.However,problems such as earlier failure and damaged of ductile cast iron often caused by the surface serious wear and corrosion during its service.The C276 and 1725 coatings on the surface of QT400-15 have been made by laser cladding to improve the wear resistance and corrosion resistance of ductile iron surface.The results show that these two coatings have better forming quality,and better wear resistance and corrosion resistance compared with cast iron.The relatively low-cost 1725 powder is chosen to prepare the 1725/WC composite coating to further improve the surface properties of cast iron.The optimal single-pass cladding process is obtained through orthogonal experiment,and the optimal processing parameters are laser power 2000 W,15 mm/s scanning speed,10 g/min powder feed rate.Taking the above single-pass cladding process for reference,a multi-track cladding with an overlapping ratio of 40%is carried out.The microstructure and properties of the coatings are analyzed at the power of 1500W,2000W,and 2500W through single factor experiments.The higher the power,the coarser the structure,the lower the hardness,and the corrosion resistance increases firstly and then decreases.Two new phases of WC and W₂C are founded owing to the addition of WC particles by analyzing the microstructure and property of the cladding with different WC weight ratios（0%,15%,30%,45%）when the power is 2000W.And the coating is strengthened by fine-rained strengthening,solid solution strengthening,dispersion strengthening and precipitation strengthening.The hardness of the cladding layer increases as the proportion of WC increases,but both of the corrosion resistance and wear resistance increase firstly and then decrease.The comprehensive property achieves the best when the WC ratio is 30%.The weightlessness of wear at 1 h is 212.0 times lower than that of the cast iron substrate and 61.1 times lower than the 1725 coating.The self-corrosion current density is 3.5 times lower than the substrate and 2.4 times lower than the 1725 coating.Figure 44;Table 11;Reference 87...