Effects of Welding Sequence on Residual Stress and Welding Deformation of Aluminum Alloy Frame of Electric Vehicle Battery Box

Aiming at the difficult problems of aluminum alloy frame of electric vehicle battery box, such as complex structure, many welding seams and high requirements of dimensional accuracy after welding, a method of simultaneous MIG welding with four welding guns was proposed. Based on numerical simulation technology, the residual stress and welding deformation of four frames with different welding sequences were compared and analyzed.The results show that the residual stress distribution of the battery box frame with four welding strategies is similar, mainly concentrated in the weld. The average value of maximum equivalent residual stress of "M" shape from outside to inside welding strategy is the minimum, which is 147 MPa. The distribution of deformation varies greatly with different welding strategies. The welding sequence of "W" shape alternating inside and outside is adopted. First, the middle beam, short beam and frame are connected together, which increases the deformation resistance of the battery box frame.Then the rest of the welds are welded.The balanced and symmetrical state of the frame can offset part of the deformation. The maximum deformation is 0.54 mm, which is the minimum deformation in the four welding strategies.