Study on Fatigue Performance of Non-Uniform Thickness Markless Laser Lap Welding

In this paper fatigue properties of three groups of unequal thickness unmarked overlap laser welding of the external wallboard connected of type A and B vehicle were studied. In addition, a group of overlap penetration welded structures of 1.5mm-301L-HT+0.8mm-301L-DLT is designed to study the impact of penetration rate to the mechanical properties. The influence of the weld geometry and plate combination on fatigue fracture behavior and fatigue property is studied based on the combination of fatigue test and simulation stress analysis. Fatigue studies have shown that in spite of the thickness of the two lap unequal thickness welded plate is disparities -- unmarked non-penetration welding outer plate is thicker but it appears fatigue fracture on the outer plate. The safety fatigue limit of three different non-penetration welded structures of plate combinations and weld structures is close which further proofs that the stress state and microstructure of non-penetration outer plate is not conducive to fatigue fracture. It is consistent with the results of the finite element simulation. The fatigue limit of lap welded structure increase with the increase of plate thickness.

Numerical simulation and experimental verification of laser multi-section welding

Aiming at the problems of large welding deformation and spatter in resistance spot welding of traditional lube oil cooler plate, a new welding method: laser multi-section welding is proposed. The major processes here involved were a finite element model of pulsed laser lap welding established using SYSWELD simulation software, and the laser welding process of different welding methods. Study the influence of different welding methods on welding quality, Optimize the parameters of average power and duty cycle according to the comparative analysis of experimental results and numerical simulation Experimental results indicate: When the new 6-sections welding method is adopted, the resulting welded joint has the most uniform heat input, the largest welding fusion area, the tensile properties of the welded joints were significantly improved, however, there are still pores. By changing the duty cycle, air holes can be effectively eliminated to further improve the quality of the joint.