Study On The Microstructure And Properties Of Mn13 Steel Plasma Fusion Coated Tungsten Carbide-nickel Based Alloy Composite Coating

The plasma cladding of tungsten carbide-nickel based alloy composite coating on the surface of high manganese steel can significantly improve its wear resistance and lifetime,but there is little research on the presence of tungsten carbide in the composite coating and its influence on the microstructure and properties of the coating.In this thesis,tungsten carbide-nickel based alloy composite coating was prepared on high manganese steel substrate by plasma cladding technology,and the influence of process parameters on the microstructure and properties of the clad tungsten carbide-nickel based alloy composite coating was investigated to investigate the melting of tungsten carbide under high energy input of plasma and the influence of the presence of tungsten carbide in the coating form and on the microstructure and properties of the coating.It is expected to provide process and theoretical references for the application of plasma melting tungsten carbide-nickel based alloy coating on high manganese steel to improve its performance.The thickness increases with the increase of current,from 1.01 mm to 1.53 mm;the thickness decreases with the speed of melting,from 1.48 mm to 0.96 mm;the thickness increases with the increase of powder feeding,from 1.15 mm to 1.39 mm;the coating dilution rate is 20%～40%,and the orthogonal analysis shows that the main factor affecting the coating dilution rate is The current,followed by the amount of powder feeding,and the melting speed has the weakest influence,the law is:the dilution rate decreases with the increase of current and then increases,from 37%to 25%,and then increases to 40%;the dilution rate decreases with the acceleration of melting speed,from 37%to 30%;the dilution rate decreases with the increase of powder feeding,from 39%to 26%.（2）The analysis of the phase composition of the composite coating shows that the organization of the coating mainly consists of nickel-based solid solution（Ni,Fe）and WC phases,mixed with trace amounts of Cr₂₃C₆,Cr₇C₃,Fe₃W₃C and W₂C phases,etc.The process parameters only change the intensity and position of the diffraction peaks,the more powder is fed,the stronger the intensity of the WC,W₂C,Cr₂₃C₆and Fe₃W₃C diffraction peaks,the higher the current（3）Histomorphological analysis shows that the WC particles in the coating show an increasing gradient from the surface to the bottom of the coating;there are significant differences in the coating histomorphology under different process parameters,the dark tissue is nickel-based solid solution,and the bright tissue is the melting of undissolved tungsten carbide and WC particles in the coating after the solid solution of C elements with W,Ni,Fe and other alloying elements to form structurally complex carbides.（4）The highest surface hardness of the prepared tungsten carbide-nickel based alloy composite coating is 621.77 HV0.5.The orthogonal analysis shows that the main factor influencing the surface hardness of the coating is the current,followed by the melting speed,and the powder feeding quantity has the weakest influence,and the influence law is that the surface hardness of the coating decreases with the increase of the current,decreases with the acceleration of the melting speed,and increases and then decreases with the increase of the powder feeding quantity.The surface hardness is higher when the coating surface contains fishbone carbide,which is 547.93-621.77 HV0.5;the hardness of the coating surface and the middle is higher,and the hardness of the bottom is lower.（5）The wear amount of high manganese steel substrate at room temperature reaches20.0 mg,and most of the coating wear amount is within 5.0 mg.The orthogonal analysis shows that the main factor affecting the coating wear amount is current,followed by powder feeding amount,and the influence of melting speed is the weakest,and the wear amount increases first and then decreases with the increase of current,increases and then decreases with the increase of melting speed,and decreases with the increase of powder feeding amount The wear amount decreases with the increase of current,increases and then decreases with the increase of cladding speed,and decreases with the increase of powder feeding;the wear amount is smaller when the coating surface contains fishbone carbide,0.5-1.2 mg.（6）Overall,the current of 100 A,the melting speed of 35 mm/s and the powder feeding rate of 15 g/min resulted in higher hardness and better wear resistance of the clad layer,which were the better process parameters obtained in this paper.