Laser Cladding Of Co Based Alloy On 304 Stainless Steel

304 stainless steel is widely used because of its good corrosion resistance and heat resistance.However,in the coastal area,304 stainless steel is prone to wear,corrosion and other failure behaviors due to the existence of corrosive media in the environment.Therefore,using laser cladding technology to improve the surface properties of 304stainless steel is of great significance to improve its service life.In this paper,304stainless steel was used as substrate and Co Cr W alloy powder was used as coating material.Single pass single factor test,orthogonal test and multi pass lap test were adopted to analyze the macro morphology of the coating,optimize the process parameters,and study the microstructure,wear resistance and corrosion resistance of the coating.By analyzing the macro morphology and dilution ratio of the coating,it is found that the parameters affecting the width of the cladding layer from large to small are:laser power P(generally significant),powder feeding rate V_f(insignificant),scanning speed V_s(insignificant);The parameters that affect the dilution ratio from large to small are:laser power P(significant),scanning speed V_s(significant),powder feeding rate V_f(generally significant).The optimal parameters of single pass are:laser power 1000W,scanning speed 8mm/s,powder feeding rate 1.8r/min,and the lap rate is 30%optimal.The results show that the microstructure of the coating is plane crystal,columnar crystal,dendrite and equiaxed crystal from the bonding zone to the surface.The SEM and EDS analysis showed that the coating contained?-Co,Cr₇C₃,M₂₃C₆,etc.The results show that the grain growth direction and grain size of the coating vary greatly under different lap ratios.The crystal near the previous coating area grows towards the top of the previous coating,and the crystal near the latter coating grows towards the top of the latter coating;When the lap ratio is 30%,the microstructure distribution of the coating is regular,the grain size is small and there is no obvious defect.The results show that the coating has the best performance when the lap ratio is30%,and its microhardness is about 450HV,which is 2.1 times of that of the substrate;The average friction coefficient is about 0.4,and the total wear amount is 12.71mg,which is 0.6 and 0.2 times of the matrix,respectively;The hardness and wear resistance of the coating are improved obviously.The Cr₇C₃and M₂₃C₆phases in the coating play the role of strengthening phase,which further increases the wear resistance and corrosion resistance of the coating.The results show that the microstructure distribution is uniform after lap remelting,which can reduce the composition segregation,and Cr and Ni elements are conducive to the passivation of the coating at low potential and passivation at low potential.The self corrosion current density of the coating is 5.7?A/cm²,which is 0.14 times of the matrix.The results show that the coating can effectively improve the wear resistance and corrosion resistance of the material surface.