Improved mechanical properties of laser-arc hybrid welded Al/steel dissimilar butt-joint through beam oscillation

Al/steel butt-joints are hard to be fusion welded because of the easily formed and unevenly distributed brittle intermetallic compounds (IMCs) at the interface. Laser-arc hybrid welding was used to suppress the IMCs formation and improve its uniformity through beam oscillation. The weld defects of uneven formation and lack of fusion were suppressed at optimised frequency of 150 Hz. Furthermore, the interface was transferred from an uneven two-layer IMCs (≥ 3.8 µm), including Al₅Fe₂ and Al1₃Fe_4, to a uniform single-layer Al₅Fe₂ (≤ 1.4 µm). Owing to these changes, not only the tensile property was increased by 65% compared to non-oscillating weld, but also the bending property that hardly reported in most studies was enhanced by 96%.