Study On Modification Technology And Microstructure Of 316L Stainless Steel By Laser Cladding With Wire-powder

316L stainless steel has excellent corrosion resistance,becoming one of the most used stainless steels varieties.Its service environment is complex and changeable,and it faces serious damage caused by chemical corrosion,electrochemical corrosion,high-energy impact,cyclic load,friction and wear and other physical and chemical synergies.Scholars at home and abroad have carried out a lot of research and exploration around the surface modification laser cladding technology of stainless steel,but the existing laser cladding equipment basically adopts the feeding way of single wire or single powder,the flexibility and utilization rate of materials are limited.In view of the above situation,the laser cladding technology test of 316L stainless steel surface with 316L solid wire+Al powder was carried out in this paper,and the microstructure,mechanical properties,wear resistance and corrosion resistance of the cladding layer were analyzed.In order to realize the laser cladding of fiber optics combined with fiber optics,a set of robot laser cladding equipment of fiber optics combined with fiber optics was designed and integrated.The main work completed in this paper is as follows:（1）The design of structure and control scheme of fiber laser cladding equipment for combined wire-powder robot.The wire-powder combined robot fiber laser cladding equipment is effectively integrated by motion system,energy system,control system,feeding system and auxiliary system.Through the selection of each equipment,it is determined that the energy system is composed of IPG fiber laser and optical coaxial powder feeding cladding nozzle.The motion system is ABB six-axis robot.The feeding system is composed of TIG-Mate wire feeder and double channel air carrier powder feeder.The control system is ABB IRC5.The auxiliary system consists of water-cooling equipment,shielding gas equipment and power supply system.（2）The influence of process parameters on the macroscopic morphology,phase composition and metallographic structure of the cladding layer.With the increase of laser power,the diffraction peak intensity of Al Fe₃ gradually changes in the range ofθ=42°～46°.The diffraction peak intensity of Cr-Ni solid solution,Al Ni,Fe Ni,Al Cr Fe₂ and other intermetallic compounds is basically unchanged.When P=1700 W,serious intergranular segregation occurs and the mechanical properties of the cladding layer decrease seriously.With the increase of the ratio of filament to powder,the intensity of diffraction peaks of Al Ni,Al Cr Fe₂ and other intermetallic compounds increased gradually in the range of θ=79°～83°,and the grains became smaller and changed to equiaxed grains,and the orientation was uniform.When R=10:3,the diffraction intensity in theθ=42°～46°diffraction range changes abruptly,and the intensity decreases obviously.When R=15:4,the heat-affected zone range of cladding layer is the smallest,and the grains are full of regular arrangement of fine strengthening phases.With the increase of scanning speed,Al,Cr,Fe,Ni and other metal atoms cannot react adequately in the molten pool,and micro-slag is formed in the interlayer microstructure of the cladding layer.The diffraction peak intensity of Al Cr,Al Ni,Al Fe,Al Cr Fe and other intermetallic compounds decreased in theθ=42°～46°range.When the scanning speed v=2 cm/s,the heat accumulation is serious and the matrix is burned through,v=5 cm/s,and the fast speed leads to the metal welding wire cannot be melted quickly.（4）Microstructure and properties of cladding layer.Al is distributed in a continuous pattern at the interface of the cladding layer,and its distribution is relatively uniform.In the cladding layer,intermetallic compounds（IMCs）and solid solutions such as Al Cr₂,Al Cr Fe₂ and Al Ni are formed.And there are a large number of regular arrangements of the diameter of d₄=200nm～500 nm tetragonal pyramid.The hardness of cladding layer is about 2.75 times higher than that of matrix.The friction volume loss is much less than that of 316L stainless steel matrix.E_corr is higher than 316L stainless steel,and I_corr is smaller than 316L stainless steel.Wear resistance and corrosion resistance are significantly improved.