WE Colloquium: Yi Huang, Aluminum welding and joining in some vehicle application
Aluminum, because of inherent advantages, is widely used in the industry, especially gradually adopted in vehicle structures. The application of this lightweight material, compared to traditional steel structure, can significantly reduce vehicle weight, and further reduce energy consumption. The aluminum structure in the powertrain assembly has numerous advantages over other ones, such as light weight, good thermal conductivity, corrosion resistance, etc.. However, in the powertrain structures, especially battery structure for electric vehicles, one of the basic requirements is low welding temperature but to realize water leak-free performance. Brazing is widely selected in this kind of application area but with high joining temperature which is usually over 450℃. Coating soldering process was developed to realize low soldering temperature and relative high joining strength. Ni and SnCu alloy plating baths were developed to reduce the stress in Ni layer. The influence of electric deposition parameters of Ni and SnCu alloy on the coating quality and subsequent solderability were analyzed. Soldering flux was adopted to remove the oxidation before joining. By adopting proper soldering temperature profile, solid soldering joint was obtained. The peak temperature was around 360℃. The lap shear strength can reach around 20MPa and the joint fractured at the interface of the intermetallic compound and Sn-rich phase. Water leak-free structure was realized with low joining temperature.
Aluminum is also widely used in the body structure to reduce vehicle weight. Resistance spot welding is one of the major processes to realize this design. However, due to high thermal conductivity, low melting temperature, high electric resistance, small plastic range, and other property, it is hard to achieve stable weld quality compared to steel structure. The major concerns were analyzed, and potential equipment and process set up were proposed to achieve stable welding quality.
Dr. Yi Huang received his PhD Degree in Electrical and Computer Engineering (Welding Major) from the University of Kentucky, Lexington, Kentucky in 2011, and M.S. in Materials Engineering (Welding Major) and B.S. in Welding Engineering from the State Key Laboratory for Advanced Welding and Joining, Harbin Institute of Technology, Harbin, China, in 2006 and 2004, respectively. His major research interests include novel welding and joining processes development for advanced materials, welding and joining metallurgy especially for microjoining, and analytical modeling of materials joining process, and dissimilar material welding and joining.
Dr. Huang is currently employed as a Staff Advanced Manufacturing Engineer at Tesla Motors, Fremont, CA. He leads Welding and Joining R&D team for exploring novel welding and joining processes for current and future vehicle models, and welding and joining processes selection and qualification, design, cost control, equipment introduction and launching for body in white, closure in white, battery enclosure, seat framing, and other structure assembly. Dr. Huang has published more than 20 papers in peer-reviewed journals and conferences. He was the recipient of the A. F. Davis Silver Medal Award for Machine Design in 2011 and Charles H. Jennings Memorial Awards in 2012 from American Welding Society (AWS), and Henry Granjon Prize for Joining and Fabrication Technology from International Institute of Welding in 2012.