6082铝合金双面搅拌摩擦焊接头组织与性能

Research on microstructure and properties of double-sided friction stir welding joint of 6082 aluminum alloy

文中研究了改变搅拌针针长与焊缝相对位置对25 mm厚6082-T6铝合金双面搅拌摩擦焊接头组织与性能的影响规律.结果表明,当搅拌针针长不足以覆盖1/2板厚时,针端搅拌力不足,焊缝中心存在大尺寸缺陷,拉伸与弯曲性能较差;当搅拌针针长超过1/2板厚0.5 mm时,焊缝中心依然存在间隙,但不明显影响拉伸与弯曲性能;当继续增加搅拌针针长时,焊缝中心缺陷消除,弯曲性能良好,但接头强度随针长继续增加而降低.针长为14 mm时接头综合性能最好;同时发现焊接方向与横向偏移方向影响接头弯曲性能,当反面焊缝向后退侧偏移2.5 mm时,弯曲试样完好,当反面焊缝向前进侧偏移2.5 mm时,性能较为薄弱的后退侧HAZ会靠近焊缝中心,导致弯曲试样开裂.

The effects of needle length and weld position on microstructure and properties of 25 mm thick 6082-T6 aluminum alloy double-sided friction stir welding were studied in this paper. The results show that when the length of thestirring needle is not enough to cover half the thickness of theplate, the stirring force at the end of the stirring needle isinsufficient, and there exist large defect in the weld center, andthe tensile and bending properties are poor. When the length ofthe stirring needle is just over 1/2 plate thickness, there is still asmall defect in the weld center, but it does not affect the tensileand bending properties obviously. When the length of thestirring needle continues to increase, the defects in the center ofthe weld are eliminated and the bending performance is good,but the joint strength decreases with the needle lengthcontinues to increase. In this study, the joint comprehensiveperformance is the best when the needle length is 14 mm. Atthe same time, it is found that the welding direction and thelateral offset direction affect the bending performance of thejoint. When the reverse weld is offset by 2.5 mm to the retreatside, the bending sample is intact. When the reverse weld isoffset by 2.5 mm to the advanced side, the backward HAZwith weaker performance will be close to the weld center,leading to the cracking of the bending sample.