5B70 aluminum alloy plates with a thickness of 1.5 mm were welded using tungsten inert gas (TIG) welding with 5B71 filler wire. The mechanical properties and microstructures of the welded joints were investigated. The results show that under appropriate welding parameters

joints with excellent mechanical properties could be achieved. The tensile strength reached 342–350 MPa

the joint strength coefficient was 0.82–0.84

and the elongation at fracture was 9.5%–13%. The weld hardness ranged from 87HV to 93HV

with the minimum hardness located near the fusion line. The hardness profile exhibited a double V-shape. The fracture surface displayed a 45° shear morphology

characterized by a mixed mode of dimples and cleavage facets

with strengthening phase particles observed within some dimples. The fusion line of the joint was distinct

and the microstructures differed across the weld zone

fusion line

heat-affected zone

and base metal. The weld zone consisted of refined equiaxed grains with nonuniform sizes.