Solid-State Ultrasonic Spot Welding of Lightweight Alloys for Automotive Applications
Daolun Chen
Professor, Ph.D., Dr.rer.nat., P.Eng.
Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, Canada
Phone: (416) 979-5000 ext. 6487, Fax: (416) 979-5265,
Email: dchen@ryerson.ca, Web: http://www.ryerson.ca/~dchen
Vehicle lightweighting is today recognized as one of the most important strategies to improve fuel efficiency and reduce anthropogenic climate-changing, environment-damaging, costly and human death-causing emissions, since every 10% reduction in weight would lead to about 6.6% to 8% increase in fuel efficiency. Indeed, it has recently been portrayed as the “storm” of lightweighting – a revolution in materials, processes, and business models – which is brewing on the horizon of the automotive industry. Lightweight alloys including magnesium (Mg) alloys and aluminum (Al) alloys have thus been increasingly used in the transportation industry. The structural applications of these materials inevitably involve welding and joining. Some emerging and promising solid-state welding techniques, such as ultrasonic spot welding, friction stir (spot) welding, have been developed to join the lightweight alloys in both similar and dissimilar material combinations. In this talk several examples on the welding of similar Mg/Mg and Al/Al and dissimilar Mg/Al, Mg/steel and Al/steel using ultrasonic spot welding and friction stir welding will be presented. The weld interface experienced dynamic recrystallization during similar welding, while an intermetallic compound layer or a eutectic layer was formed during dissimilar welding, depending on the material combinations. To eliminate/minimize the occurrence of intermetallic compounds, an interlayer or coating (tin or zinc) was also used during dissimilar welding. It was observed that the tensile lap shear strength of the dissimilar welded joints was effectively enhanced. The evolution in the microstructure and texture as well as fatigue properties and fracture mechanisms of the welded joints will be presented.
Brief Biography: Dr. Chen is a Professor in the Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, Canada. He received his Ph.D. from the Institute of Metal Research, Chinese Academy of Sciences, 1989, and Dr.rer.nat. from the University of Vienna, Austria, 1993. Dr. Chen has authored over 330 refereed publications (including 253 journal papers and 82 conference papers) mainly in the area of advanced materials (bio- and nano-materials, composites, etc.) and other critical engineering materials, and their mechanical properties, plus additional 165 non-refereed conference papers/abstracts/research reports. His research findings have been widely cited by other researchers, including those cited in 81 overview papers, 43 books or book chapters, and 4 handbooks or sourcebooks. According to an analysis by the Council of Canadian Academies, Dr. Chen is identified to be an author of one of the top 1% most highly cited papers in his field worldwide. He is a recipient of a number of prestigious awards including Premier’s Research Excellence Award, Natural Sciences and Engineering Research Council of Canada (NSERC) DAS Award, MetSoc Award for Research Excellence, Sarwan Sahota Distinguished Scholar Award, Ryerson inaugural Faculty SRC Award, and Ryerson Research Chair. Dr. Chen is an Associate Editor or a member of Editorial Board of 21 journals. He is currently a member of NSERC Grant Selection Committee and Scientific Expert Evaluator of European Commission Horizon 2020 Programme. More information could be seen on his web site at http://www.ryerson.ca/~dchen/biography.html .
