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采用蔡氏显微镜、扫描电镜、透射电镜及拉伸试验研究三次循环深冷处理前后车用6005A合金焊接接头组织与性能的演变规律。结果表明:经过三次循环深冷处理,6005A铝合金焊接接头出现若干强化相β-Mg_2Si,期间弥散分布Si、α-AlFeSi等细小析出相。同时,循环深冷处理促使焊接区域形成大量的位错,抵消焊接热输入过程中产生的强大内应力,提升合金焊缝区域抗拉强度至234 MPa;此外,循环深冷处理后拉伸断口区域组织呈细小、平坦的延性韧窝结构。
The evolution of microstructure and properties of 6005A alloy welded joint before and after three cycles cryogenic treatment was studied by means of Chua’s microscope, scanning electron microscope, transmission electron microscope and tensile test. The results show that after three cycles of cryogenic treatment, a few precipitated phases of β-Mg_2Si appear in the welded joints of 6005A aluminum alloy, while small precipitates such as Si and α-AlFeSi are dispersedly dispersed. At the same time, cyclic cryogenic treatment led to a large number of dislocations in the welding area, counteracting the strong internal stress generated during welding heat input, and increasing the tensile strength of the weld area to 234 MPa. In addition, the microstructure of the tensile fracture zone after cyclic cryogenic treatment Small, flat ductile dimple structure.