Effect of different laser welding processes on high strain rate performance of 6005A-T6 aluminum alloy welded joints

In this paper,butt joint with 3 mm 6005A-T6 aluminum alloy was taken as the main object of study.The samples were welded by laser wire filling welding,laser-MIG welding and laser-CMT welding,and were tested with a high strain rate to obtain the true stress-true strain curve.Tensile fractures were analyzed by SEM to compare high-speed tensile properties of the three welding methods.Johnson-Cook constitutive equations’parameters of welding processes were calculated correspondingly by fitting to their plastic deformation parts of testing curves.The results showed that the tensile strength of the laser wire filling welded joints was the highest at the high strain rate of 200 s-1,while the joints’tensile strength of the other two welding processes was a little bit lower.The fracture mode was ductile.The curve of Johnson-Cook constitutive equation fit the testing curve well for each welding process,and it accurately described the variation of flow stress under high strain rate.Highlights:(1)The dynamic mechanical properties of 6005A-T6 aluminum alloy welded joints at high strain rates were studied.By fitting the Johnson-Cook constitutive equation curves of the plastic deformation section of three welding processes,it was found that the tensile strength of laser wire filled joints was the highest at the typical high strain rate of 200 s-1,while that of laser-MIG and laser-CMT hybrid welding was slightly lower.(2)The Johnson-Cook constitutive equation curve of each welding process fit well with the test curve,which could predict the plastic deformation of joints of different welding processes under high strain rate,and provide data support for the lightweight design of body structure and the optimization and improvement of welding method and other processes in actual production.