Research On Laser Cladding Layer On The Surface Of The Stainless Steel And Its Properties

316L stainless steel has excellent oxidation resistance,corrosion resistance and high-temperature resistance,so it is widely used in petrochemical,aviation and automotive industries.However,the single-phase austenite organization leads to low surface hardness and poor wear resistance of stainless steel,resulting in 316L stainless steel parts are prone to wear loss in service,which brings greater safety risks to industrial production.Laser cladding technology is one of the important methods of stainless steel surface repair or modification,the processing loss is small,no waste liquid outflow,the prepared coating performance is excellent,in line with China’s green development concept.Therefore,in this paper,Inconel 718/Ce O₂ fusion coating was prepared on the surface of 316L stainless steel by laser cladding technology,and the effects of different laser power,scanning speed and Ce O₂ content on the physical phase as well as microstructure of the coating were investigated to analyze the change law of coating properties.The specific research contents of this paper are as follows:（1）To investigate the effect of laser power on the organization and properties of Inconel 718coatings,Inconel 718 coatings were prepared at different laser powers（1400,1600 and 1800 W）while keeping the scanning speed constant(2 mm·s^-1).The results showed that the physical phase composition of the coatings prepared at different laser powers was consistent and consisted ofγ～（Fe,Ni）solid solution,Ni₃N_b,MC_X（M=Cr,Nb,Mo）and other physical phases.As the laser power increases,the hardness of the coating decreases and the wear resistance first improves and then decreases.When the laser power is 1600W,the coating organization consists of plane crystal,columnar crystal,cellular crystal and equiaxed crystal,and the mechanical properties of the coating are excellent,with an average microhardness of 604.6 HV_0.2,which is 3.1 times the hardness of the 316L stainless steel;the friction coefficient is 0.3,which is significantly lower than that of the substrate（0.6）;the wear rate is 2.97×10^-5 mm³·N^-1·m^-1,which is only 20%of the wear rate of the substrate.（2）To investigate the effect of scanning speed on the organization and properties of Inconel718 coatings,Inconel 718 coatings were prepared at different scanning speeds(1.5,2 and 2.5 mm·s^-1)while keeping the laser power constant（1600 W）.The results show that the scanning speed also does not change the phase composition of the coatings,which all consist ofγ～（Fe,Ni）solid solution,MC_X（M=Cr,Nb,Mo）and other phases.With the increase of the scanning speed,the hardness and wear resistance of the coating first increased and then decreased.The dendritic morphology of the coating of the scanning speed of 2 mm·s^-1 was regular and orderly,with high hardness(604.6 HV_0.2)and uniform distribution,and the frictional wear morphology was relatively smooth,and the wear mechanism occurred by abrasive wear and adhesive wear.（3）To investigate the effect of Ce O₂ content on the organization and properties of Inconel718 coatings,Inconel 718 coatings with different Ce O₂ contents（0,1,2,3,4 and 5 wt.%）were prepared using the obtained optimum process parameters.The results showed that the coatings with different Ce O₂ contents were composed ofγ～（Fe,Ni）solid solution,Ni₃Nb and MC_X（M=Cr,Nb,Mo）phases,and no Ce₂O₃ phase appeared in the coatings when the Ce O₂ content was 1wt.%;Ce₂O₃ phase was generated in the coatings when the Ce O₂ content was 2,3,4 and 5 wt.%.With the increase of Ce O₂ content,the grain size in the coating first decreases and then increases,and the corresponding hardness and wear resistance first increases and then decreases,but it has little effect on the corrosion resistance of the coating.When the Ce O₂ content is 2 wt.%,the coating has a fine tissue,the average microhardness is the largest(771.6 HV_0.2),the friction coefficient（0.126）and wear rate(0.94×10^-5 mm³·N^-1·m^-1)are the lowest,and the wear resistance is the best;the self-corrosion potential is-0.495 V,the self-corrosion current density is 2.05×10^-4 A·cm^-2,and the self-corrosion potential is the highest.At this time,the self-corrosion potential is the highest and the self-corrosion current density is the lowest.