Study On The Control Of Welding Residual Stress And Distortion By Trailing Cooling Of Argon Gas For Al/Steel Thin Sheet

In recent years,Al/steel integrated structures have been increasingly used in automobiles,aerospace and ships to obtain high-strength lightweight structures,thus further reducing fuel consumption and air pollution.But Al/steel dissimilar metal sheet welding is usually accompanied by large residual stress and deformation,which affects the manufacturing accuracy and performance of the structure.In order to control the welding stress and deformation of Al/steel thin plate,this paper presents the argon-induced cooling technology with welding,and studies the controlled deformation and stress of Al/steel thin plate with argon-induced cooling technology by combining test and simulation.A self-made cooling gas device with welding,a welding test platform,a regular tig welding of Al/steel sheet and a cold welding test with welding are carried out.It is verified from the test that the cooling process with welding can effectively reduce the deformation and residual stress after welding of Al/steel thin plate.Thermocouple is used to collect the temperature and thermal cycle curve of a certain point in the welding process,the residual stress of the test plate after Al/steel welding is measured by stress and strain meter,and the deformation of the test plate after welding is measured by three coordinate measuring instrument,which is prepared to verify the accuracy of the numerical simulation.By using ANSYS numerical simulation software,the geometric model is established according to the actual welded joint,and the heat source and cold source models are established at the same time.The temperature field and stress field of Al/steel welding are simulated by indirect coupling method,and the accuracy of the model is verified by combining the test results.The distribution of temperature field and stress field of conventional welding and cold welding with welding is compar ed and analyzed,and the mechanism of controlling welding deformation and stress with welding cold technology is expounded.Using the established finite element model,the effect of different cooling parameters on the stress strain of Al/steel welding is studied.The results show that the smaller the cooling distance without affecting the welding quality,the better the control effect;the increase of cooling strength is beneficial to reduce the welding deformation and residual stress;the cooling diameter of the cold source is 8 mm,and the distance of the cold source is 10 mm.Compared with conventional welding,longitudinal residual tensile stress peak and residual compressive stress peak decreased by 42.1% and 74.4%,transverse residual tensile stress pe ak and residual compressive stress peak decreased by 11.3% and 14.4%,respectively.the deformation of outer edge of aluminum plate and steel plate decreased by 67.9% and 69.5%,respectively,compared with conventional welding.The macroscopic morphology,microstructure and mechanical properties of Al/steel welded joints were compared with those of different welding processes.The results show that there is no obvious difference between the macroscopic morphology,microstructure and mechanical properties of Al/steel welded joints and conventional welded joints during the cold welding test with welding.Under certain conditions,the intermetallic compound thickness of Al/steel welded joints can be reduced with the welding exciting cooling technology,and the purpose of controlling the welding deformation and stress of Al/steel sheet without affecting the mechanical properties of welded joints is realized.