Fatigue properties of 2A12/6061 dissimilar aluminum alloy TIG welded lap joints
Tungsten inert gas(TIG)welding was conducted on 3 mm thick 2A12/6061 dissimilar aluminum alloy plates,and the fatigue performance of the joints was analyzed using optical microscope,microhardness tester,scanning electron microscopy and fatigue testing machine.Based on the experimental results,a finite element model was established for the lap joint specimen,and the fatigue life of the joint was predicted using the hot spot stress method and compared with the experimental results.The results show that the microstructure of the weld zone is uniform equiaxed grains,and the fusion between the 2A12 side weld and the base metal is poor,with a significant difference in strength,resulting in metallurgical defects and large stress gradients at the 2A12 side weld toe,thereby accelerating the initiation of fatigue cracks.Under different load levels,the fracture location of the specimen is located at the 2A12 side weld toe with significant strength differences,exhibiting a brittle-plastic complex fracture characteristics.Metallurgical defects at the weld toe and local strength differences in the weld are the main factors that affect the fatigue performance of the joint.The fatigue life prediction results indicate that the hot spot stress method considering the plate thickness effect is accurate,with an error within a double error band.The FAT40 S-N curve recommended by IIW is considered safe and reliable.
heterogeneous aluminum alloyTIG weldingfatigue strengthhot spot stress methodfatigue life
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