Process optimisation and mechanical properties of friction stir lap welds of 7075-T6 stringers on 2024-T3 skin
Process optimisation and mechanical properties of friction stir lap welds of 7075-T6 stringers on 2024-T3 skin
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DOI：
10.1016/j.matdes.2010.02.002
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发表时间：
2010-08-01
影响因子：
8.4
通讯作者：
Jahazi, M.
中科院分区：
文献类型：
--
作者：
Dubourg, L.;Merati, A.;Jahazi, M.
本文着重于工艺优化和机械试验的结果，用于确定使用搅拌摩擦焊（FSW）连接纵梁到皮肤的可行性。研究了工艺参数对1.5 mm 7075-T6纵梁搭接在2.3 mm 2024-T3蒙皮上的焊缝质量的影响。关节配置上的前进和后退侧位置交替，以确定最佳的设计安排。还研究了行进速度和旋转速度对焊接质量和缺陷产生的影响。焊接质量进行了评估，通过光学显微镜和弯曲试验。结果发现：（i）焊接速度的增加或旋转速度的降低导致钩状尺寸的减小和顶板变薄，但没有消除它们，（ii）通过重叠前进侧的双道焊接通过克服钩状缺陷而显著地改善了焊接质量，以及（iii）用左螺纹探针将旋转方向改变为逆时针，消除了顶部薄片变薄缺陷。随后，搅拌摩擦焊搭接接头生产使用最佳条件，并进行了广泛的机械测试程序。生产了几种装配配置，包括不连续和连续焊缝以及单道和双道焊缝。FSW板的循环疲劳性能所获得的结果进行了比较相同的几何形状的铆接搭接接头。S-N曲线，弯曲行为，破坏位置和缺陷表征也进行了讨论。结果发现：（i）搅拌摩擦焊接接头的抗拉强度接近母材的抗拉强度，但疲劳寿命显著降低，（ii）探针插入和移除位置是不连续焊缝试样中的关键裂纹成核位置，（iii）具有重叠前进侧的双道焊缝显示出出色的疲劳寿命和非常好的拉伸性能。本文的工作为搅拌摩擦焊在桁条/蒙皮搭接接头上的制造和应用提供了一些有价值的见解。(C)2010爱思唯尔有限公司保留所有权利。
This paper focuses on the results of process optimisation and mechanical tests that were used to ascertain the feasibility of using friction stir welding (FSW) to join stringers to skin. The effects of process parameters on weld quality of 1.5-mm 7075-T6 stringers lap-joined on 2.3-mm 2024-T3 skins were investigated. Advancing and retreating side locations on the joint configuration were alternated to determine optimal design arrangements. The effects of travel and rotation speeds on weld quality and defect generation were also investigated. Weld quality was assessed by optical microscopy and bending tests. It was found that: (i) the increase of the welding speed or the decrease of the rotational speed resulted in a reduction of the hooking size and top plate thinning but did not eliminated them, (ii) double pass welds by overlapping the advancing sides improved significantly the weld quality by overriding the hooking defect, and (iii) change of the rotational direction for a counter clockwise with a left-threaded probe eliminated the top sheet thinning defect. Subsequently, FSW lap joints were produced using optimum conditions and underwent extensive mechanical testing program. Several assembly configurations including discontinuous and continuous welds as well as single and double pass welds were produced. The results obtained for cyclic fatigue performance of FSW panels are compared with riveted lap joints of identical geometry. S-N curves, bending behaviour, failure locations and defect characterisation are also discussed. It was found that: (i) the tensile strength of FSW joints approached that of the base material but with a significant reduction in the fatigue life, (ii) the probe plunge and removal locations served as the key crack nucleation sites in specimens with discontinuous welds, and (iii) double pass welds with overlapping advancing sides showed outstanding fatigue life and very good tensile properties. The present work provided some valuable insight into both the fabrication and application of FSW on stringer/skin lap joints. (C) 2010 Elsevier Ltd. All rights reserved.