题目：Ultrasonic Spot Welding of Lightweight Alloys for Automotive Applications
报告人：Prof. Daolun Chen
时间：9月27日（周三），上午9:00-11:00
地点：师昌绪楼403室
The transportation industry is facing mounting pressures in several key areas including energy, emissions, and safety. Lightweighting is one of the most effective strategies to address these challenges, since a 10% weight reduction results in a 6~8% fuel-efficiency gain. 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. Vehicle lightweighting can be better achieved via a “multi-material” concept, where the characteristics of different materials (e.g., aluminum and magnesium alloys) are optimized for the desired applications for lightweighting, cost effectiveness and value addition. The structural applications of such multi-materials inevitably involve welding and joining, particularly dissimilar welding. This poses significant challenges due to different physical, mechanical and thermal properties and the related safety and durability issues of welded joints. In this talk several examples on the ultrasonic spot welding of similar Mg/Mg and Al/Al and dissimilar Mg/Al, Mg/steel and Al/steel 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.
作者简介：陈道伦博士是加拿大工程院院士，加拿大瑞尔森大学大学机械和工业工程系教授。1983和1986年于东北大学分获学士与硕士学位，1989年于中国科学院金属研究所获工学博士学位，1993于奥地利维也纳大学获自然科学博士学位。已在先进材料和关键工程材料及其变形、疲劳、焊接方面发表350多篇学术论文期刊，以及180篇以上的非国际会议论文/研究报告。他的研究成果产生了很好的影响。根据加拿大学术委员会在2011和2016的分析，他两次被鉴定为“在其研究领域内被引用次数世界前1%的论文作者之一”。他获得了多个奖项和荣誉，包括：总理杰出研究奖、加拿大自然科学和工程研究委员会（NSERC）DAS奖、冶金与材料学会优秀科研奖/著名材料科学家奖、Sarwan Sahota杰出学者奖。他是Mater Sci Eng A、Mater Design 等27个期刊的副主编或编辑委员会成员。他经常受到科学记者的邀请，就Nature 与 Science杂志发表的一些重大科学突破进行采访和评论，还是NSERC资助遴选委员会和欧盟地平线2020计划科学评估专家成员。更多的信息可以看他的网站http://www.ryerson.ca/~dchen/biography.html.
