Microstructure Characteristics in Multi-Pass Welding Interface of Al-Mg Alloy

Al-Mg alloy plates with 10mm thick were welded by multi-pass MIG welding with the self-made wire as filler material, and microstructure of the welded joint were examined by metallographic and electron backscatter diffraction (EBSD). The results indicate, because of the grain refining effect of Zr, the grains in welding joints fusion zone formed grain-refining layer tissue by competitive growth. In the juncture zone of two welding passes, because of the grain epitaxial growth mechanism, it formed obvious coarse grain zone, which became a weak link of welding joints. And the coarse grain zone exist faint <110> texture, but to the whole, the welding zone did not exist obvious preferred orientation.