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对Mg-6Zn-1Gd合金搅拌摩擦焊接头进行固溶处理,采用金相显微镜(OM)、扫描电镜(SEM)、能谱仪(EDS)以及显微硬度测试和室温拉伸试验研究了固溶处理对接头组织和性能的影响。结果表明,在430℃进行固溶处理时,焊核区平均晶粒尺寸随着固溶时间的延长而逐渐增大;当固溶时间超过2 h后,其晶粒尺寸长大更为显著,4 h时达到46μm,约为未固溶接头的3.5倍。焊核区的第二相则由大块状共晶组织逐渐破碎、溶解为小颗粒状组织,其面积分数随固溶处理时间的延长逐渐减少。固溶处理后接头发生了“软化”现象,焊核区的显微硬度下降明显,最大下降幅度超过20%。接头的抗拉强度随固溶时间的延长呈现先升高后降低的趋势,而伸长率则逐渐提高。当固溶时间为2 h时,接头抗拉强度达到最高,较原接头提高32.5%,约为母材的85.5%。
The friction stir welded joints of Mg-6Zn-1Gd alloy were treated by solution treatment. The solution treatment was studied by OM, SEM, EDS, micro-hardness test and tensile test at room temperature Impact on joint organization and performance. The results show that when the solution treatment at 430 ℃, the average grain size of the weld nugget increases with the increase of the solution time. When the solution time exceeds 2 h, the grain size grows more obviously. Reached 46μm at 4 h, which was about 3.5 times of that of unsoluble solution. The second phase of the nugget zone is gradually crushed by the massive eutectic structure, dissolving into small granular structure, and its area fraction gradually decreases with the prolongation of solution treatment time. After solution treatment, the phenomenon of “softening” occurred in the joint, and the microhardness of the nugget core area decreased obviously with the largest decrease of more than 20%. Tensile strength of the joint increases first and then decreases with the increase of solution time, but the elongation increases gradually. When the solution time is 2 h, the joint tensile strength reaches the highest, which is 32.5% higher than the original joint, about 85.5% of the base metal.