Process And Theoretical Study Of Laser Welding Carbon Fiber Composite And Stainless Steel

Carbon fiber composite(CFRP)is one of the most ideal materials to replace metal in the field of lightweight.But CFRP can’t be used to completely replace metal materials.It is necessary to replace part of the metal with CFRP to form CFRP-metal structural parts.Laser connection can effectively solve the connection problem between the dissimilar materials.But using lasers to connect CFRP to metal inevitably induces defects such as bubbles in the joints,these defects can lead to reduced service life of the joint.n this paper,the laser welding process of CFRP and stainless steel is studied by numerical simulation and experiment,and the influence of bubbles and other defects on the joint bonding strength is evaluated.The main research contents and conclusions are as follows:(1)Simulation of laser welding CFRP and Stainless steel.The influence of laser power,scanning speed,resin type and other parameters on the temperature field in the material was studied.he results show that the maximum temperature of resin layer temperature field and stainless-steel surface temperature field increase with the increase of laser power,but decrease with the increase of scanning speed.The selection window of laser welding speed increases with the increase of laser power.The larger the temperature difference between the gasification point and the melting point of the resin,the larger the window of process parameters.The width of the molten pool formed by the resin layer increases with the increase of laser power and the decrease of scanning speed.(2)Study on pretreatment of laser welding CFRP-Stainless Steel.The effects of laser power,scanning speed,defocusing amount and other process parameters on the removal efficiency of CFRP surface resin were studied.The results show that the higher the laser power,the cleaner the resin removal on CFRP surface,but the higher the laser power will damage the carbon fiber.The higher the scanning speed,the more residual resin on the surface of CFRP,and the higher the scanning speed will lead to inadequate resin removal.The residual resin on CFRP surface increases with the increase of defocus,but the thermal damage of carbon fiber on CFRP surface decreases.(3)Experimental study on laser welding of CFRP and Stainless steel.The influence law of process parameters(resin removal rate,laser power,scanning speed,resin type)on the connection strength was studied,and the bubble defect at the joint and the failure form of the joint were analyzed.The results show that the joint bonding strength decreases with the increase of laser power after approaching the maximum value.The joint strength increases first and then decreases with the increase of scanning speed.The larger the bubble size,the lower the binding strength.The removal of CFRP surface resin is helpful to improve the bonding strength of the joint.When the filling resin is polyphenylene sulfide resin,the failure modes of CFRP-stainless steel joints are cohesive failure and interface failure simultaneously.When the filling resin is polyether ether ketone resin,the failure mode of CFRP-stainless steel joint is the interface failure of CFRP.When the filling resin is polyamide 66 resin,the failure mode of CFRP-stainless steel joint is mainly the cohesive failure of resin matrix and a small amount of CFRP interface failure.