2024-T351/5083-H112 异种铝合金搅拌摩擦焊接头低周疲劳性能

Dissimilar 2024-T351 to 5083-H112 aluminum alloys were butt welded by friction stir welding. The effects of base material location (Advancing side and retreating side) on the joint formation, microstructure, cyclic deformation behavior and fatigue life were analyzed. The results indicate that the upper zone of stir zone (SZ) is almost covered by the base material (BM) which is placed on the retreating side (RS). The plastic metal in the SZ more sufficiently flows when 2024-T351 aluminum alloy is located on the advancing side (AS). Thus, a joint without flaws is fabricated. A highly asymmetric microhardness distribution is obtained in 2024-T351 and 5083-H112 sides. The hysteresis loops area of the joints placing 5083-H112 on the AS is larger than that of the joint positioning 5083-H112 on the RS. At the total strain amplitude of 0.3%, 0.4% and 0.6%, the cyclic hardening phenomenon obviously occurs. A joint with longer fatigue life is obtained when 2024-T351 is located on the AS. At the total strain amplitude of 0.2%, the periodical structures appear in the fracture morphology of fatigue specimen. Moreover, dimples and tear ridges can be observed in these periodical structures. At the total strain amplitude of 0.6%, large numbers of dimples appear in the fracture morphology which is similar to that tensile fracture morphology.