Microstructures and Mechanical Properties of Mg Alloy FSW Joint Characterized with Asymmetric Gradient in Three Dimension

Abstract:

Friction stir welding (FSW) experiments were carried out on AZ31 magnesium alloy under the optimized welding parameters. The temperature distribution, macrostructure and microstructure, mechanical properties of the joint were studied along three dimensions (transverse direction, longitudinal direction, thickness direction). Temperature distribution, joint appearance and microstructure demonstrate asymmetric gradient in three dimensions. The peak temperature of featured points at the welding beginning stage was lower, and the one in the ending stage was higher. The temperature of advancing side was higher than that of the retreating side. More in detail, the dynamically recrystallized microstructure in weld nugget zone (WNZ) was uniform and small. The thermomechanically affected zones (TMAZ) closed to the WNZ, which were characterized with bended and elongated grains. At advancing side, the interface between TMAZ and WNZ was very distinct. The microhardness distribution showed a typical W shape. The profile showed a slightly lower hardness in the WNZ than in the base metal,HAZ, and TMAZ correspond to the lowest one. The FSW joints were observed to fail mostly at the boundary between WNZ and TMAZ at the advancing side.

• Periodical: Materials Science Forum (Volume 749)
• Pages: 180-186
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.749.180
• Online since: March 2013
• Authors: Sheng Lu, Dai Li Yang, Shi Yu Xiao, Ali Lu
• Keywords: Friction Stir Welding (FSW), Magnesium Alloy, Temperature Field, There-Dimensional

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