Achieving low-porosity and high-strength 2219 aluminum alloy joints through coupling of laser beam oscillation and post-weld heat treatment

Abstract

Laser welding is a highly promising joining method for Al alloys. However, certain limitations such as elevated thermal input and keyhole instability are associated with its application in medium-thickness aluminium alloy plates. To address these issues, circular oscillating laser welding combined with post-weld heat treatment was employed to improve the formation quality and mechanical properties of the welds. The effects of the frequency of circular oscillating laser on the forming quality, microstructure, and properties of the welds were analyzed. At an oscillation frequency of 200 Hz, the grain size in the weld zone was reduced compared to single laser welding, and the maximum tensile strength of the weld was observed to reach (264.96±1.33) MPa, representing approximately 61.19% of the base metal. Following the post-weld heat treatment of “solid solution and artificial aging”, the grain boundary segregation was diminished. Nanoscale precipitated phases are present in the weld zone. Furthermore, the tensile strength was augmented to (386.35±5.65) MPa, representing approximately 89.23% of the strength of the base metal. The results of this study can provide a theoretical basis and technological reference for the circular oscillating laser welding of medium-thickness 2219-T6 aluminium alloy plates.

Keywords

2219 aluminium alloy / circular oscillating laser welding / parameter optimization / porosity / post-weld heat treatment / mechanical enhancement

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