Effect of initial microstructure on Ti–6Al–4V joint by friction stir welding
Effect of initial microstructure on Ti–6Al–4V joint by friction stir welding
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DOI：
10.1016/j.matdes.2015.09.128
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发表时间：
2015-12
影响因子：
8.4
通讯作者：
Sungook Yoon;R. Ueji;H. Fujii
中科院分区：
文献类型：
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作者：
Sungook Yoon;R. Ueji;H. Fujii
采用搅拌摩擦焊（FSW）对具有不同大角度晶界密度的3种初始组织的Ti-6Al-4V合金板进行了连接，研究了搅拌区的组织演变规律。关于显微组织的形态，所有三种接头显示出相似的特征; SZ的上表面呈现出片层组织与等轴α晶粒的混合物，并且由于温度梯度，等轴α晶粒的面积分数随着离上表面的距离的增加而逐渐增加。另一方面，随着大角度晶界初始密度的增加，完全等轴α组织区的平均α晶粒尺寸减小。从组织不均匀性对再结晶的影响角度讨论了这种加速晶粒细化的作用。
Ti–6Al–4V alloy plates with three types of initial microstructures, which have different densities of the high angle boundaries, were joined by friction stir welding (FSW), and the microstructure evolution in the stir zone by the FSW was clarified. Concerning the morphology of the microstructure, all three joints show similar characteristics; the top surface of the SZs exhibited a mixture of the lamellar structure with equiaxed α grains and the area fraction of the equiaxed α grain gradually increased with the increasing distance from the top surface due to the temperature gradient. On the other hand, the mean α grain size of the fully equiaxed α structure area decreased with the increasing initial density of high angle boundaries. This accelerated grain refinement was discussed based on the effect of the inhomogeneous microstructure on the recrystallization.