Current issues and problems in laser welding of automotive aluminium alloys

The automotive industry is facing demands simultaneously to increase its fleet average fuel economy and to reduce the emission of greenhouse gases by its products. In order to meet these new standards, the industry is increasingly aiming to decrease the weight of vehicles through the use of new materials, especially lightweight aluminium alloys. Laser welding is a critical enabling technology in reducing the weight of the body structure through increased use of aluminium and tailor welded blanks. In this review the available research on the laser welding of 5xxx, 6xxx, and some 2xxx series automotive aluminium alloys is critically examined and interpreted from different perspectives. First, the current understanding of the important physical processes occurring during laser welding of these alloys such as energy absorption, fluid flow and heat transfer in the weld pool, and alloying element vaporisation are examined. Second, the structure and properties of these weldments are critically evaluated. Third, commonly encountered defects found in laser welded automotive grade aluminium alloys and their science based remedies are discussed. Finally, several important unanswered questions related to laser welding are identified and an outlook on future trends in the laser-welding of automotive grade aluminium alloys is presented. The review is written for scientists and materials engineers who are not specialists in welding, practising engineers in the automotive industry, welding engineers, and researchers in this field.