中国激光, 2018, 45 (3): 0302003, 网络出版: 2018-03-20   

激光复合焊接7020铝合金的疲劳性能及损伤行为 下载: 695次

Fatigue Property and Fracture Behavior of 7020 Aluminum Alloys Welded by Laser-MIG Hybrid Welding
作者单位
1 西南交通大学牵引动力国家重点实验室, 四川 成都 610031
2 中国科学院上海应用物理研究所上海同步辐射光源, 上海 201204
3 中国科学院高能物理研究所北京同步辐射装置, 北京 100049
摘要
通过激光-熔化极稀有气体保护电弧(MIG)复合焊得到了7020铝合金焊接接头,基于电子背散射衍射技术和高精度同步辐射X射线成像等,研究了该接头微观组织、力学性能、疲劳行为及断裂机制。结果表明,在焊接热循环作用下,冷却后复合焊接头各区域的晶粒形态、尺寸及组织成分发生了明显变化。接头静载抗拉强度和屈服强度分别为265.34 MPa和218.85 MPa,接头强度系数为0.74。在50%存活率下,当疲劳寿命为2×106循环周次时,复合焊接头的疲劳强度为96.13 MPa,约为母材的63.14%,焊接过程降低了材料的疲劳性能。疲劳裂纹萌生于复合焊接头熔合区表面深约103 μm的缺口处,呈典型I型四分之一椭圆裂纹扩展形貌。在稳定扩展阶段,气孔对疲劳裂纹扩展速率的影响较小。
Abstract
The 7020 aluminum alloy joints welded by laser-metal inert-gas arc (MIG) hybrid welding are obtained. The microstructure, mechanical properties, fatigue performance and fracture mechanism of these hybrid welded joints are investigated by the techniques of electron backscatter diffraction and high resolution synchrotron radiation X-ray micro-tomography. The results show that, under the influence of thermal circulation in welding, the grain morphology, size and chemical constituent in different zones of butt-welded joints after cooling show obvious changes. The static tensile strength, yield strength and welding coefficient of hybrid welded joints are 265.34 MPa, 218.85 MPa and 0.74, respectively. When the fatigue life is 2×106 cycles and the survival is 50%, the fatigue strength of hybrid welded joints is 96.13 MPa, and is about 63.14% of that of the base metal, which shows that the welding process significantly deteriorates the performance against fatigue. It is found that the fatigue cracks initiate from a notch with 103 μm depth at the surface in the fusion zone, and show a typical I mode quarter elliptical crack profile. The pores have little effect on the crack growth rate in the stable extension stage.

胡雅楠, 吴圣川, 宋哲, 付亚楠, 袁清习. 激光复合焊接7020铝合金的疲劳性能及损伤行为[J]. 中国激光, 2018, 45(3): 0302003. Hu Yanan, Wu Shengchuan, Song Zhe, Fu Yanan, Yuan qingxi. Fatigue Property and Fracture Behavior of 7020 Aluminum Alloys Welded by Laser-MIG Hybrid Welding[J]. Chinese Journal of Lasers, 2018, 45(3): 0302003.

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