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研究12 mm厚AA7075-T651铝合金板搅拌摩擦焊接头的疲劳裂纹扩展行为。从搅拌摩擦焊接头以及母材中截取试样,对试样进行疲劳裂纹扩展实验。对搅拌摩擦焊接头以及母材的横向拉伸性能进行评估。用光学显微镜和透射电镜分析焊接接头的显微组织。用扫描电镜观察试样的断裂表面。与母材相比,焊接接头的ΔKcr降低了10×10-3 MPa·m1/2。搅拌摩擦焊AA7075-T651接头的疲劳寿命明显低于母材的,其原因可归结于焊缝区的析出相在搅拌摩擦焊接过程中的溶解。
Study on Fatigue Crack Growth Behavior of 12 mm Thick AA7075-T651 Aluminum Alloy Plate in Friction Stir Welding. Samples were taken from the friction stir welded joints and the base metal to carry out fatigue crack propagation experiments on the specimens. The transverse tensile properties of the friction stir welded joints and base metal were evaluated. The microstructure of welded joint was analyzed by optical microscope and transmission electron microscope. The broken surface of the sample was observed with a scanning electron microscope. Compared with the base metal, the weld joint ΔKcr decreased by 10 × 10-3 MPa · m1 / 2. The fatigue life of AA7075-T651 joint is obviously lower than that of base metal in friction stir welding. The reason for this may be attributed to the dissolution of the precipitated phase in the weld zone during friction stir welding.