Numerical Analysis and in-situ Observation of bubble Behavior and Microporosity Formation in Laser Beam Welds of Aluminum Alloy

Abstract

Aluminum alloys are useful structural materials to make automobiles lighter. But, in the case of welding for aluminum alloys, large distortion occurs due to its large thermal conductivity and thermal expansion ratio. From the view point of heat input suppression, laser beam welding (LBW) is one of effective approach to put the alloys into practical use. However, one of other big problems to adopt the alloys as structural materials with welding is weld defects such as porosity, hot cracking, and so on. Thus, development of the method to draw proper welding method and its conditions more efficiently is demanded, in order to improve productivity due to breaking away from current search methods by trial and error. Therefore, in order to clarify the mechanism of porosity in weld metal on LBW process and suggest proper welding conditions without any defects, numerical analysis based on fluid dynamic theories and in-situ observation using X-ray transmission real-time imaging system were conducted in this study.