growing public concern, some vehicle architecture changes may be needed to offset issues surroundingThe automotive industry is facing demands the relationship between vehicle weight and safety, simultaneously to increase its fleet average fuel economy and to reduce the emission of with increasing use of spaceframes, or spaceframe greenhouse gases by its products. In order to meet subassemblies expected. Increased use of technologies these new standards, the industry is increasingly such as hydroforming that can be used to produce aiming to decrease the weight of vehicles through complex single piece sections, further decreasing the use of new materials, especially lightweight weight, while enhancing structural strength and stiffaluminium alloys. Laser welding is a critical ness, will also be seen. All of these technologies are enabling technology in reducing the weight of the likely to be implemented in aluminium as well as in body structure through increased use of steel, as the weight of the body structure drops.aluminium and tailor welded blanks. In this reviewInevitably, this will lead to needs for new jointhe available research on the laser welding of ing technologies for automotive aluminium alloys. 5xxx, 6xxx, and some 2xxx series automotive aluminium alloys is critically examined and Resistance spot welding (RSW) is the most important interpreted from different perspectives. First, the welding process now used in autobody construction. current understanding of the important physical While RSW is a nearly ideal process for the assembly processes occurring during laser welding of these of stamped steel body structures, offering robustness alloys such as energy absorption, fluid flow and and low cost, it is more costly and less robust when heat transfer in the weld pool, and alloying used on aluminium structures. Further, increased use element vaporisation are examined. Second, the of closed sections made via hydroforming will require structure and properties of these weldments are processes other than RSW. Introducing tailor welded critically evaluated. Third, commonly encountered blanks in aluminium will also require new joining defects found in laser welded automotive grade aluminium alloys and their science based capability to support high volume production. remedies are discussed. Finally, several important Laser welding is a particularly interesting approach unanswered questions related to laser welding are to the construction of advanced automotive body identified and an outlook on future trends in the structures because of its high speed, low heat input, laser welding of automotive grade aluminium and flexibility. Among laser welding's potential benalloys is presented. The review is written for efits are thinner flanges, the ability to produce tailor scientists and materials engineers who are not welded blanks, and reduced distortion in hydroformed specialists in welding, practising engineers in the frame structures. New developments in laser techautomotive industry, welding engineers, and nology, su...

A technique for in-situ measurement of the surface tension of molten steel droplets in a gas-metalarc welding plasma is described. Surface tension measurements obtained using this method are reported for ER70S-6 wire, with varying shielding gas compositions, and compared with previously reported results. The in-situ technique is found to produce results consistent with values found in the literature, while incorporating the effects of alloy composition and arc atmosphere.

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The surface tension of detached liquid drops in pulsed gas metal arc welding was determined in situ from the period of the prolate-oblate oscillations initiated by the detachment event. The oscillating drops were imaged by an optical shadowgraph technique utilizing laser illumination. Images obtained during the welding process were recorded with a high-speed video camera and stored for subsequent analysis. For 4047 aluminium alloy wire, surface tension values in the range 0.54-0.7 N m −1 were obtained for various droplet sizes.