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Joining of Aluminum to Steel with Butt Joint Using Welding-brazing Method

Zhuguo Li
Shanghai Jiao Tong University

Abstract:

Butt joining of AA6061 aluminum alloy and Q235 low-carbon steel was conducted using welding-brazing method. A hot-dip galvanized process or an electro-galvanizing process was performed to obtain a zinc coating at the steel's bevel surface. Different heat input and wire feed rate were tried. The weld appearance, brazing interface, and tensile strength were observed and evaluated. It is feasible to join aluminum alloy to steel when zinc layer was obtained at the steel's groove face compared that without zinc coating, and the zinc coating could markedly improve the wetting of weld metal on the bevel surface of the steel. Sound weld appearance can be obtained at appropriate welding parameters. The joints had dual characteristics of a welding joint on the aluminum side and a brazing joint on the steel side. The smooth Fe2Al5 layer adjacent to the steel matrix and the serrated-shape FeAl3 layer close to the weld metal were formed at the brazing interface. The average thickness of Fe-Al intermetallic compounds layers produced was less than 10┬Ám at various welding parameters. The mechanical strength of the joint was mainly depended on the area of the brazing interface and maximum tensile strength of 175Mpa was achieved. The joint had a better performance with an electro-galvanizing coating and a smaller bevel angle of the steel. The fracture surface presented a typical cleavage fracture mode. All the joints failed in the Fe2Al5 layer.

Biography:

Prof. ZHUGUO LI has obtained Bachelor degrees in Welding and Automation in 1994 from Shanghai Jiao Tong University, and a Master degree in Welding Engineering in 1997 from the same university, and a Ph.D in Materials Processing Science from Osaka University in 2004. Since then he has joined Shanghai Jiao Tong University. He has became a full professor since 2010. Now Prof. LI ZHUGUO is the vice dean of School of Materials Science and Engineering Shanghai Jiao Tong University, and the director of Shanghai Key Laboratory of Materials Laser Processing and Modification. He also serves as the Deputy Secretary General of China Welding Society. His research interests include laser welding, laser cladding and laser additive manufacturing, and he is the co-author of more than 150 SCI-papers published on peer-review journals.

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