研究2024铝合金搅拌摩擦焊缝在空气、预腐蚀与3.5%盐水腐蚀液中的疲劳与裂纹扩展性能，并采用 SEM对断口的近门槛区、稳定扩展区与瞬断区进行观测。结果表明，腐蚀环境对铝合金搅拌摩擦焊缝的寿命产生很大影响，焊缝的腐蚀疲劳寿命只有空气中的一半左右；焊缝的裂纹扩展速率比母材快，在腐蚀环境下，随着应力强度因子幅度的增大，母材与焊缝裂纹扩展速率的差距越来越大，但预腐蚀损伤对焊缝的裂纹扩展速率影响较小，只是降低了裂纹萌生寿命。
In this investigation, 2024 aluminium alloy plates were friction stir welded, a sequence of experiments was performed including fatigue and crack propagation tests in air, under pre-corrosion and in a 3.5% NaCl solution, in combination with fractography analyses of near-threshold region, Paris region and finial fracture region with the aid of scanning electron microscopy (SEM). Results showed that the corrosive environment caused a dramatical decrease in fatigue lives of FS welds, the corrosion fatigue lives of FS welds were almost a half of those of the as-welded specimens. The crack growth rates in FS welds were higher than their counterparts in base materials, under the corrosive environment, the crack growth rate differences between base materials and FS welds become increasingly apparent with the increase of stress intensity factor range ΔK, but the pre-corrosion process had little effect on the FS welds’ crack propagation behavior except for shortening the crack initiation lives greatly.
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