Improvement in tensile strength of Mg/Al alloy dissimilar friction stir welding joints by reducing intermetallic compounds

• Published in: Journal of alloys and compounds 2021-04, Vol.861, p.157942, Article 157942
• Main Authors: Chen, Wei, Wang, Wenxian, Liu, Zepeng, Zhai, Xin, Bian, Gongbo, Zhang, Tingting, Dong, Peng
• Format: Article
• Language: English
• Subjects: 6061 Al alloy; AZ31B Mg alloy; Friction stir welding; Intermetallic compounds; Tensile strength; Thermal cycles
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.157942

There has been an increasing demand for joining Al to Mg in transportation vehicles to reduce weight further. However, it is difficult to manufacture high performance Mg/Al dissimilar joints due to the formation of massive intermetallic compounds (IMCs) during welding. In the present study, AZ31B Mg and 6061 Al were friction stir welded with a high joint efficiency by reducing the IMCs formation. Microstructural observations were conducted by using optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), and the results showed that the content of IMCs reduced from about 31.79% to 7.8%. Mechanical test results showed the tensile strength of joint increase from 92 MPa to 168 MPa. The findings provide an alternative to improve Mg/Al dissimilar joint strength. •Formation of different Mg/Al intermetallic compounds is made clear.•The reason why Al3Mg2 eutectic microstructure does not occur is explained.•The intermetallic compounds are reduced with the increase of the cooling capacity of the different coolants.•The performance of Mg/Al joints are improved by reducing intermetallic compounds.