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采用搅拌摩擦焊对厚度为30 mm的7A52铝合金厚板进行对接单道焊接,并沿厚度方向每6 mm切取共制成5层疲劳试样,研究其疲劳性能的变化趋势。结果表明:沿厚度方向由表层至底部疲劳性能依次呈先减后增的变化趋势,沿焊接方向疲劳性能呈先减后增而后再减的变化趋势;接头疲劳断裂位置和显微硬度的最低处大部分出现在前进侧的热影响区;焊缝断口形貌较母材复杂,断口瞬断区出现沿晶断裂,伴有较厚的撕裂棱;韧窝内第二相粒子发生劈裂和碎裂。
7A52 aluminum alloy plate with a thickness of 30 mm was welded by single-pass welding with friction stir welding, and a total of 5 layers of fatigue specimens were cut every 6 mm along the thickness direction to study the change tendency of the fatigue properties. The results show that the fatigue behavior along the thickness from the surface to the bottom decreases in the order of decreasing first and then increasing, and the fatigue property decreases firstly and then increases and then decreases again along the welding direction; the lowest fatigue fracture location and the lowest microhardness Most of them appear in the heat-affected zone on the advancing side. The weld fracture morphology is more complicated than that of the base metal, and the intergranular fracture occurs in the fracture instantaneous area with a thick tearing edge. The second phase particles in the dimples splitting and Fragmentation.