| With the rapid development of my country’s high-speed train industry,the lightweight has become an inevitable trend in the development of the railway transportation industry.For the 6005 A aluminum alloy profile for high-speed train welding,different welding processes,clamping positions,clamping types,welding sequence and other factors will have certain effects on the residual stress and deformation after welding,which will affect the fatigue performance of the welded joint.In this paper,the finite element numerical simulation method is used to study the residual stress and deformation of laser wire welding 6005 A aluminum alloy profiles after welding.Through the welding process parameter test of laser wire welding of 6005 A aluminum alloy flat plate,the welding process parameters under different heat input were obtained under the premise of ensuring stable penetration and good appearance molding.After verifying the heat source model with this parameter,the numerical simulation of the welding seam of the profile was carried out to determine the heat input range of the profile welding.The welding temperature field of aluminum alloy profiles is calculated,and the results show that the welding process of the lower plate surface of the profile has almost no effect on the thermal cycle curve of the upper plate surface.The calculation results of the residual stress field of the aluminum alloy profile show that the residual stress after welding is mainly distributed on both sides of the weld,showing a bimodal distribution.The peak residual stress is 165 MPa,which is located near the fusion line of the weld and is 67% of the yield strength of the base material.When the clamping position of the fixture is 12 mm from the center of the weld,the peak residual stress drops by 12%;when the clamping position of the fixture is 36 mm from the center of the weld,the peak of residual stress drops by 4%.When the clamping position of the fixture is greater than 65 mm from the center of the weld,the residual stress no longer changes.The use of long-type clamping can reduce the peak residual stress by 30% and obtain a smaller residual stress distribution range than the key-type clamping.The difference between the welding direction of the upper weld and the lower weld has basically no effect on the residual stress after welding.Under the same clamping conditions,the welding sequence has no effect on the peak value of the residual stress of the profile after welding.The welding sequence of the profile from the middle to both sides of the profile is smaller than that of other welding sequences.In the length direction of the weld,the welding sequence from the middle to both sides can effectively separate the residual tensile stress area.The calculation results of the deformation of the aluminum alloy profile after welding show that the welding process of the lower weld seam will produce the reverse deformation effect on the upper weld seam,which can effectively eliminate the angular deformation of the upper weld seam after welding.The final post-weld deformation of the profile is mainly transverse shrinkage.The closer the distance between the fixture and the welding seam,the smaller the final lateral shrinkage of the profile.When the distance between the clamping position of the fixture and the center of the weld is less than 65 mm,warpage and deformation are likely to occur at the web.The post-weld deformation caused by the long-type clamping is less than that of the piano-type clamping;when the welding direction of the lower welding seam is different from that of the upper welding seam,the reverse deformation of the lower welding seam will not completely eliminate the angular deformation of the upper welding seam,so that the deformation of the entire profile increases after welding.Using the welding sequence from the middle to both sides produces the least amount of post-weld deformation.The post-weld deformation simulation results of the complex roof structure of highspeed trains show that the welding sequence of welding small components first and then welding large components can obtain a small amount of lateral shrinkage after welding. |
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