Study on the properties of 6082 aluminum alloy lap welding joint
The 6 mm thick 6082 aluminum alloy lap joint was welded by MIG welding.The effects of different process parameters on the appearance,microstructure and mechanical properties of welded joints were studied,and the fracture morphology was analyzed by SEM.It was found that with the decrease of welding speed and the increase of welding heat input,the porosity gathered at the top of the weld and the porosity at the root of the weld decreased.Softening occured in the heat-affected zone,and the hardness value of heat-affected zone was lower than weld zone.The metallurgical structure near the heat-affected zone was columnar crystal structure.The fusion zone was equiaxed crystal structure,and intracrystalline liquefaction was found in the heat-affected zone,Mg,Si,Fe,Mn and other alloy elements was segregated in the weld which form intergranular precipitates.The maximum tensile strength of the lap joint was 222 MPa.Although there were a lot of porosities in the weld,the fracture behavior was still ductile fracture.
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