Challenges in Fusion Welding of Al alloy for Body in White

Abstract

Since the beginning of 21st century automobile industries are under great pressure to fulfill environmental regulations as well as user driven strict requirements such as low cost, safety, exhaust emissions, fuel efficiency, drivability, comfort and larger interior space. One of the options to address few of these challenges is reducing fuel consumption and so, it is now crucial for all the automobile manufacturers to get breakthrough in this direction. Various measures in engine modifications and hybrid systems are developed to reduce fuel consumption. However, main thrust area is automotive weight reduction, which is regarded as one of the most effective means for decreasing fuel consumption by replacing steel with aluminum. At present aluminum weight per vehicle is around 180 Kg/vehicle which will be increased to 250 Kg./vehicle by 2025. Joining of aluminum and repair of the aluminum in automobile body panels is still remain big challenge because of inherent properties of aluminum like low melting point, high thermal conductivity, high solubility of hydrogen, oxide formation and high solidification shrinkage. Aluminum is not forgiving material like still and produces several defects during welding of aluminum alloy. Hot tears, solidifying cracks, porosity, distortion and melt through are commonly observed in weld bead. Such defects drastically reduce fatigue strength and mechanical properties of aluminum alloy plates. These defects can be tackled by developing best practices in fusion welding. Especially in MIG welding, correct filler rod selection, reduced heat input, inert gas selection, welding techniques etc... can provide better quality weld beads in aluminum.