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研究厚度为10和16 mm AA7075-T651板的搅拌摩擦焊接过程。通过仔细选择焊接过程参数可获得无缺陷、全渗透焊接样品。两种焊接接头都出现极细的再结晶粒,而10 mm厚板焊接接头的晶粒组织更细。试样的显微组织观察结果表明,焊件热影响区的硬度显著降低。16 mm厚合金板焊接接头的硬度降低较大。与16 mm厚合金板相比,10 mm厚合金板焊件具有较优的拉伸性能。在拉伸实验过程中,两种厚度的合金板焊件均在热影响区发生断裂。样品的TEM结果表明,热影响区由沿晶界的宽化无沉积区和晶体内沉淀的部分溶解组成。因此,采用搅拌摩擦焊在AA7075-T651上可制得单道次无缺陷焊件,且10 mm厚合金板焊件表现出较高的焊接效率。
Friction stir welding of AA7075-T651 plates of 10 and 16 mm in thickness was studied. A defect-free, full penetration weld sample is obtained by careful selection of the welding process parameters. Both types of welded joints showed very fine recrystallized grains, while the 10 mm thick welded joints had finer grain structures. The microstructure observation results of the samples show that the hardness of the HAZ of the weldment is significantly reduced. Hardness reduction of 16 mm thick alloy plate welded joints is large. Compared with 16 mm thick alloy plate, 10 mm thick alloy plate weldment has better tensile properties. During the tensile test, the weld of both thicknesses was fractured in the HAZ. The TEM results show that the HAZ consists of a wide range of non-sedimentary zones along the grain boundaries and partial dissolution of the precipitates in the crystals. Therefore, the use of friction stir welding on the AA7075-T651 can be made single defect-free weldment, and 10 mm thick alloy plate weldment showed a higher welding efficiency.