Influence of Test Temperature on the Tensile Properties along the Thickness in a Friction Stir Welded Aluminum Alloy
Influence of Test Temperature on the Tensile Properties along the Thickness in a Friction Stir Welded Aluminum Alloy
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DOI：
10.1016/j.jmst.2015.07.005
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发表时间：
2015-09
影响因子：
10.9
通讯作者：
Weifeng Xu;Jinhe Liu;Daolun L. Chen
中科院分区：
文献类型：
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作者：
Weifeng Xu;Jinhe Liu;Daolun L. Chen
研究了2219-T62铝合金厚板搅拌摩擦焊接头的微观组织及焊接温度对接头拉伸性能、应变硬化行为和断裂特征的影响。旋转速度为500 r/min时，熔核区顶部的晶粒细小、等轴再结晶组织与300 r/min时相比没有明显变化，但熔核区中部的晶粒和第二相颗粒明显粗化。屈服强度、极限抗拉强度和接头效率随试验温度的升高而降低。而伸长率则呈现相反的趋势。在不同的试验温度下，顶片的强度（216和342 MPa）均高于中片和底片，而伸长率（8.5%）较低。底部薄片的硬化能力和应变硬化指数高于顶部和中部薄片。在室温下，两种酶的活性均大于高温和低温下的酶活性。FSW焊接接头的失效区域主要集中在上片热影响区和热影响区的交界处以及中片和下片的热影响区，不同试验温度下的断口均呈现韧窝断裂特征。
The aim of this study was to evaluate microstructures and the influence of test temperature on the tensile properties, strain hardening behavior and fracture characteristics of friction stir welded (FSWed) 2219-T62 aluminum alloy thick plate joints. A fine and equiaxed recrystallized grain structure had no significant change in grains at the top of weld nugget zone (WNZ) at a rotational rate of 500 r/min compared with 300 r/min, but the grains and second-phase particles at the middle of WNZ exhibited obvious coarsening. The yield strength, ultimate tensile strength and joint efficiency were observed to decrease with increasing test temperatures. However, the elongation presented a contrast trend. Compared with the middle and bottom slices, the top slice (216 and 342 MPa) had a higher strength and a lower elongation (8.5%) at different test temperatures. Hardening capacity and strain hardening exponent of bottom slices were higher than those of the top and middle slices. Both of them at room temperature (RT) were bigger than those at higher temperature (HT) and lower temperature (LT). The FSWed joints basically failed in the border area between the thermo-mechanical affected zone (TMAZ) and heat-affected zone (HAZ) of the top slice, and in the HAZ of the middle or bottom slices, while the fracture surfaces exhibited dimple fracture characteristics at different test temperatures.