The Evolution of the Nugget Zone for Dissimilar AA6061/AA7075 Joints Fabricated via Multiple-Pass Friction Stir Welding
The Evolution of the Nugget Zone for Dissimilar AA6061/AA7075 Joints Fabricated via Multiple-Pass Friction Stir Welding
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DOI：
10.3390/met11101506
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发表时间：
2021-10-01
期刊：
影响因子：
2.9
通讯作者：
Zhang, Fenghe
中科院分区：
文献类型：
--
作者：
Chen, Yu;Cai, Zhihui;Zhang, Fenghe
采用单道和多道搅拌摩擦焊技术成功地连接了AA 6061和AA 7075铝合金，研究了第二道搭接对熔核区演变的影响及其焊接方向。与单道次搅拌摩擦焊相比，第二道次搭接延长了动态再结晶时间，熔核区晶粒细化，大角度晶界增多。此外，反向的第二个重叠道的焊接方向增强了材料的垂直流动，增加了搅拌摩擦焊的应变在熔核区。结果，在第二重叠道次期间的晶粒细化和异种材料混合的效率显著提高。由于AA 6061/AA 7075合金的晶粒细化和机械联锁，在第二道次重叠后，熔核区的抗拉强度得到改善。的熔核区，这是通过多道次摩擦搅拌焊接技术，使用相反的焊接方向制造，表现出23%的屈服强度增加相比，使用单道次摩擦搅拌焊接技术的样品。
AA6061 and AA7075 aluminum alloys were successfully joined by using single-pass and multiple-pass friction stir welding techniques after which the effects on the nugget zone evolution from a second overlapping pass and its welding direction, were investigated. In comparison to single-pass friction stir welding, the application of a second overlapping pass prolonged the dynamic recrystallization time, and the grains of the nugget zone became finer with increased high angle grain boundaries. Moreover, reversing the welding direction of the second overlapping pass enhanced the vertical flow of materials, increasing the strain of the friction stir welding in the nugget zone. As a result, the efficiency of the grain refinement and mixture of dissimilar materials during the second overlapping pass were significantly elevated. The tensile strength of the nugget zone was improved after the second overlapping pass due to both the grain refinement and mechanical interlocking of the AA6061/AA7075 alloys. The nugget zone, which was fabricated via the multiple-pass friction stir welding technique using an opposite welding direction, exhibited a 23% increase in yield strength as compared to the sample using the single-pass friction stir welding technique.