Development of liquid-nitrogen-cooling friction stir spot welding for AZ31 magnesium alloy joints
来源期刊：International Journal of Minerals Metallurgy and Materials2017年第10期
论文作者：Dong Wu Jun Shen Meng-bing Zhou Liang Cheng Jia-xing Sang
文章页码：1169 - 1176
摘 要：A liquid-nitrogen-cooling friction stir spot welding（C-FSSW） technology was developed for welding AZ31 magnesium alloy sheets. The liquid-nitrogen cooling degraded the deformability of the welded materials such that the width of interfacial cracks increased with increasing cooling time. The grain size of the stirred zone（SZ） and the heat-affected zone（HAZ） of the C-FSSW-welded joints decreased, whereas that of the thermomechanically affected zone（TMAZ） increased with increasing cooling time. The maximum tensile shear load of the C-FSSW-welded joints welded with a cooling time of 5 or 7 s was larger than that of the friction stir spot welding（FSSW）-welded joint, and the tensile shear load decreased with increasing cooling time. The microhardness of the C-FSSW-welded joints was greater than that of the FSSW-welded joint. Moreover, the microhardness of the SZ and the HAZ of the C-FSSW-welded joints increased, whereas that of the TMAZ decreased, with increasing cooling time.
Dong Wu，Jun Shen，Meng-bing Zhou，Liang Cheng，Jia-xing Sang
State Key Laboratory of Mechanical Transmission, College of Materials Science & Engineering, Chongqing University
摘 要：A liquid-nitrogen-cooling friction stir spot welding（C-FSSW） technology was developed for welding AZ31 magnesium alloy sheets. The liquid-nitrogen cooling degraded the deformability of the welded materials such that the width of interfacial cracks increased with increasing cooling time. The grain size of the stirred zone（SZ） and the heat-affected zone（HAZ） of the C-FSSW-welded joints decreased, whereas that of the thermomechanically affected zone（TMAZ） increased with increasing cooling time. The maximum tensile shear load of the C-FSSW-welded joints welded with a cooling time of 5 or 7 s was larger than that of the friction stir spot welding（FSSW）-welded joint, and the tensile shear load decreased with increasing cooling time. The microhardness of the C-FSSW-welded joints was greater than that of the FSSW-welded joint. Moreover, the microhardness of the SZ and the HAZ of the C-FSSW-welded joints increased, whereas that of the TMAZ decreased, with increasing cooling time.
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