Improvements in the Microstructure and Mechanical Properties of Aluminium Alloys Using Ultrasonic-Assisted Laser Welding

Abstract

Welding high-strength aluminium alloys is generally a delicate operation due to the degradation of mechanical properties in the thermally affected zone (TAZ) and the presence of porosities in the molten metal. Furthermore, aluminium alloys contain compounds that solidify before the rest of the base alloy, therefore acting as stress concentration points that lead to the phenomenon of hot cracking. This paper investigates the process of applying ultrasonic vibrations to the molten pool aluminium alloy AA6082 to improve both its microstructure and mechanical properties. We analysed conventional and ultrasonic-assisted laser welding processes to assess the sonication effect in the ultrasonic band 20–40 kHz. Destructive and nondestructive tests were used to compare ultrasonically processed samples to baseline samples. We achieved a 26% increase in the tensile and weld yield strengths of laser welds in the aluminium plates via the power ultrasonic irradiation of the welds under optimum ultrasonic variable values during welding. It is estimated that the ultrasound intensity in the weld melt, using a maximum power of 160 W from a pair of 28 kHz transducers, was 35.5 W/cm2 as a spatial average and 142 W/cm2 at the antinodes. Cavitation activity was significant and sometimes a main contributor to the achieved improvements in weld quality.

Experimental and Numerical Investigation of the Use of Ultrasonic Waves to Assist Laser Welding

“…The effect of ultrasonic vibration on the solidification phase significantly impacts on the final structure, mechanical properties, and electrical characteristics of the material [5]. This is particularly critical when dealing with metal alloys or combinations of dissimilar materials, as observed in lap joining for ba ery cell connectors in the production of electric vehicle ba ery packs [6,7]. The coexistence of liquid and solid phases, owing to the varying melting points of different metals, leads to the agglomeration of similar particles during solidification, which ideally should be uniformly dispersed throughout the liquid phase [8].…”

Experimental and Numerical Investigation of the Use of Ultrasonic Waves to Assist Laser Welding

“…The effect of ultrasonic vibration on the solidification phase significantly impacts the final structure, mechanical properties, and electrical characteristics of the material [ 5 ]. This is particularly critical when dealing with metal alloys or combinations of dissimilar materials, as observed in lap joining for battery cell connectors in the production of electric vehicle battery packs [ 6 , 7 ]. The coexistence of liquid and solid phases, owing to the varying melting points of different metals, leads to the agglomeration of similar particles during solidification, which ideally should be uniformly dispersed throughout the liquid phase [ 8 ].…”

On the Use of Low-Intensity Ultrasonic Vibration for Enhancing the Laser Welding

“…These vibrations yield positive outcomes such as better material flow, improved diffusion, and increased malleability [19][20][21]. Conversely, the laser energy supplies localized heat to melt and fuse the materials together [22][23][24]. By incorporating ultrasonic vibrations alongside the welding, the integration facilitates superior blending of materials, resulting in robust and dependable welds.…”