REVIEW ARTICLE


Forming and Properties of Friction Stir Welding Process for Dissimilar Mg Alloy



Tielong Li*, 1, 2, Zhenshan Wang3
1 Tianjin Key Laboratory of Advanced Joining Technology, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
2 Mechanical and Electrical Engineering Department, Yuncheng University, Yuncheng, Shanxi, 044000, China
3 Shanxi Wenxi Silver Magnesium Industry Co, LTD, Yuncheng, Shanxi, 043800, China


© 2015 Li and Wang

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: (https://creativecommons.org/licenses/by/4.0/legalcode). This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Tianjin Key Laboratory of Advanced Joining Technology, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China; Tel: +8613753918248; E-mail: 378269309@qq.com


Abstract

For hot extrusions of magnesium alloy sheets, Dissimilar AZ80 and AZ31 were used, in which AZ80 was placed on advancing side and AZ31 on retreating side, using friction stir butt welding with different process parameters. Some defect-free welded joints with good weld surfaces could be obtained with some suitable welding conditions. The maximum tensile strength of welded joint which is 225.5 MPa can reach 98% that of the AZ31 base material. Influence of process parameters on defects, weld shaping and mechanical property were discussed systematically. And the microstructure of different zones was compared. The fracture of the welded joints takes place at the junction of mechanical heat affected zone and nugget zone in AZ31 magnesium alloy set retreating side, since existing difference in metallographic structure of alloy diversely suffered by heat, pressure and depositing impurities. Fracture initiation site may be the P line defect which should be eliminated, and the P line defect formation was analyzed.

Keywords: Defect, dissimilar magnesium alloy, fracture location, friction stir welding, mechanical properties, metallographic structure.