Research On Arc Brazing Process And Connection Mechanism Of 5052 Aluminum Alloy/304 Stainless Steel With The Aid Of Cutting

Based on the solution ideas of improving the bonding strength of the joint interface and buffering the large difference in coefficient thermal expansion of dissimilar metals,based on the theories of metal milling mechanics,semi-solid rheology and diffusion dynamics,the first proposed arc welding of aluminum alloy and stainless steel with the aid of cutting tool.The welding of 5052 aluminum alloy and 304 stainless steel with a thickness of 3mm is realized through the cutting auxiliary arc welding brazing technology.The five key issues of aluminum/steel joint weld formation,interface morphology evolution,intermetallic compound,distribution of IMC particles and interfacial connection mechanism are carried out experimental research.First,optimize the design of the gnawing tool structure,discuss the influence of the number of steps and taper of the gnawing head on the formation and microstructure properties of the joint,and establish the gnawing head and process parameters-interface morphology-weld structure-mechanical properties of the joint The law of influence among the four further strengthens the stability of the gnawing assisted arc welding technology.The results show that by optimizing the structure of the gnawing head,the cutting and stirring capabilities of the gnawing head can be improved,and finally a matching relationship with the weld formation can be achieved.Based on the 6-step 15° structure of the gnawing head,the influence of different process parameters on the structure and mechanical properties of the joint is explored.Finally,the average tensile strength of the joint obtained under the conditions of 102 A welding current,3500 rpm of gnawing head rotation speed and 0.2mm gnawing amount reached 152.3 MPa,and the thickness of the interface IMC layer reached the minimum value of 3.7 ?m.The cross-section of the joint is characterized by a macroscopic wave shape,and the microscopic interface is a periodic sawtooth structure.This macroscopic wave interface and the microscopic sawtooth interface feature synergistically form a "macro and micro double self-locking structure" interface strengthening.The meshing effect is to improve the crack resistance of the interface.In addition,the precipitation phase and IMC particles in the welded seam are evenly distributed,forming a strengthening effect of weld particles,and alleviating the difference in thermal expansion coefficient between aluminum alloy and stainless steel.The combined action of "macro/micro double self-locking interface strengthening + weld particle strengthening" improves the comprehensive mechanical properties of the aluminum/steel joint and reduces the brittleness of the overall joint.A "far-to-near" gnawing-assisted arc welding test process was established.By analyzing the law of the role of the gnawing head on the aluminum/steel interface,it is found that the complete welding process includes welding wire melting to fill the assembly gap,gnawing head cutting and interface wetting,initial formation of a serrated interface,IMC layer growth on the steel substrate,IMC The coexistence of layer growth and fragmentation.A regular wave-like interface is formed on the macroscopic interface;the zigzag interface morphology is finally obtained on the microscopic interface,and the IMC layer grows wavyly along the steel matrix,which is conducive to the redistribution of interface stress.The effect of macro/micro double self-locking interface strengthening is achieved.The implementation of internal and external measures to reduce interface brittleness and release interface stress will promote the improvement of joint strength.