Effect And Mechanism Of WC On Microstructure And Properties Of Ni60 Wear-resisting Hardfacing Alloy

Today,with the vigorous development of China’s industrial production and life,manufacturing,mechanical engineering and other industries,more and more parts fail due to the corresponding wear and corrosion problems in their work.This paper mainly analyzes the abrasive wear and corresponding corrosion caused by mining machinery,cement equipment and oil transportation pipeline,and improves its surface wear resistance and corrosion resistance through surface strengthening treatment,so as to prolong the service life of workpieces and save economic costs.The following conclusions are obtained through experiments:（1）Using the control variable method,the effects of the process parameters of welding current and welding speed on the surface forming,surface microhardness and wear of surfacing layer are studied.Finally,the best process parameters are determined as follows:surfacing current 160 A,surfacing voltage 25 V and surfacing speed 8 mm/s.（2）The addition ratio is 50wt.%WC+50wt.%Ni60,welding defects such as cracks and pores begin to appear in the surfacing layer.Due to the actual demand,no follow-up research will be done on it.When WC ceramic particles are not added,the main phase of Ni60 alloy surfacing layer isα-Fe Ferriteγ（Fe,Ni）solid solution and Ni₃B₄are equal.After adding different content of WC powder,the overall phase of surfacing layer changes little,only WC,W₂C,M₇C₃and M₇C phases are formed.With the increase of WC content,the microstructure refinement effect of surfacing layer is obvious.The microstructure of surfacing layer is mainly composed of dendritic matrix and intergranular carbide.（3）The hardness test results of surfacing layer show that the hardness value of surfacing layer increases with the increase of WC content.The alloy powder is 100wt.%Ni60,the average hardness value of the surfacing layer is 543.9HV_0.5.With the addition of WC ceramic particles,the powder content is 30wt.%WC+70wt.%Ni60.The maximum hardness value of surfacing layer can reach 725.6HV_0.5.It is 3.4～3.9 times of the base metal hardness.In the wet sand wear test,when the content of alloy powder is 30wt.%WC+70wt.%Ni60,the minimum weight of surfacing layer is 2.08g.In the pin disc wear test at room temperature,the addition amount of WC is 30wt.%and 40wt.%,there is little difference in the weight of grinding loss,and the wear resistance of surfacing layer is the best.But when the powder content is 40wt.%WC+60wt.%Ni60,the friction coefficient of surfacing layer fluctuates greatly.The reason is that too much WC content of ceramic particles will lead to uneven distribution of hard phase in the microstructure of the surfacing layer,resulting in large fluctuation of the friction coefficient of the surfacing layer.（4）The corrosion test results show that the ratio of alloy powder is 100wt.%Ni60,the surface of surfacing layer is severely corroded.However,with the increase of ceramic particle WC,the self corrosion current density decreased first and then increased,and the amount of 10wt.%WC+90wt.%Ni60,the self corrosion current density reaches the minimum value of 3.7135×10^-4m A/cm².The maximum AC impedance radius and the best corrosion resistance.