Weld bead characteristics for full-penetration laser welding of aluminum alloy under electromagnetic field support

Abstract

An oscillating electromagnetic field weld pool support system combined with a welding sample travel mechanism was designed for improving the weld bead formation in full-penetration laser welding of A5083 aluminum alloy. The experimental results show that a proper oscillating electromagnetic field can effectively reduce the weld root sagging. When the root mean square of magnetic induction intensity on the back surface Brms0 = 80 m T and its electromagnetic frequency f = 400 Hz, the weld root sagging for the joint of aluminum alloy plate with thickness of 10 mm can be almost eliminated. The electromagnetic frequency and the laser power have a great impact on the weld root sagging height and the weld back surface roughness, while the influence of magnetic induction intensity is relatively small within its variable range in this study. The analysis of welding joint microstructure shows that the electromagnetic field can also refine the grains to some extent and decrease the width of columnar grain zone, decreasing the cracking susceptibility and improving the mechanical properties of the welding joint. However, the undercut defects are inevitable in full-penetration laser welding of aluminum alloy unless filler wire is used, because the metallic evaporation and splash are unavoidable during the high-power laser welding process.