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采用搅拌摩擦焊制备30 mm厚7A52铝合金对接接头,通过X射线探伤、焊缝组织与硬度分析和力学性能测试,研究焊缝疏松缺陷的存在形式、产生机理和对力学性能的影响。结果表明,疏松缺陷产生于焊缝前进侧焊核区与热机影响区交界处,主要由焊接工艺不当引起。疏松为有一定方向性的和较明显界面的、间隙的团条状组织,而且产生疏松的焊缝显微硬度和接头力学性能明显降低。带有疏松缺陷的拉伸断口没有撕裂痕迹,属于脆性断裂。
A 30 mm thick 7A52 aluminum alloy butt joint was prepared by friction stir welding. X-ray flaw detection, weld microstructure and hardness analysis and mechanical properties testing were carried out to study the existence, mechanism and mechanical properties of the weld flaw. The results show that the loose defects originate at the junction of weld zone and heat affected zone on the weld side, which is mainly caused by improper welding process. Loose to have a certain direction and the more obvious interface, the gap of the group of bar-like organizations, but also produce loose weld microhardness and mechanical properties significantly reduced joints. Tensile fracture with loose defects without tearing marks, are brittle fracture.