Microstructure and performance test of aluminum alloy K-TIG welding joint

Abstract

The K-TIG welding method was used to conduct welding experiments on 6001 aluminum alloy, and the microstructure and mechanical properties of the welded joints were studied by optical microscope, scanning electron microscope, universal testing machine, microhardness tester, etc. The results show that the center of the weld is equiaxed crystals and a small amount of dendrites, the near seam zone is columnar crystals formed by associated crystals, the fusion zone is equiaxed crystals of varying sizes, and there are grain boundary liquefaction and β″ phase in this zone. Agglomeration, growth and transformation, there are grain growth and precipitation zones in the heat-affected zone; the tensile fracture positions are all at the fusion line, and the fractures are ductile and brittle mixed quasi-cleavage fractures, with dimples, river patterns, and cleavage steps; welded joints The hardness of the fusion zone has a W-shaped distribution, and the hardness value of the fusion zone is lower due to over-aging softening.