热输入对6005A-T6铝合金双轴肩搅拌摩擦焊接头成形及力学性能的影响

Effect of heat input on formation and mechanical properties of 6005A-T6 joints by bobbin tool friction stir welding

研究了热输入对6005A-T6铝合金双轴肩搅拌摩擦焊接头成形及力学性能的影响,结果表明:塑性金属总量和挤压模的大小决定了焊缝形貌,热输入特征值WP≤1时,塑性金属总量起主要作用,焊缝呈"哑铃形",随着热输入的降低,焊缝前进侧与母材的界面逐渐变平,在前进侧产生隧道缺陷,接头抗拉强度先增加后减小; WP>1时,挤压模大小起主要作用,随着热输入的降低,焊缝前进侧与母材的界面保持平直,不产生隧道缺陷,接头抗拉强度呈增加的趋势;"S"线产生于塑性金属流动交汇处,热输入通过影响塑性金属流动,从而影响"S"线的形貌,"S"线的存在不影响接头的拉伸性能。接头显微硬度呈"W"型,这与接头各区域组织及强化相有关。

6005 A-T6 aluminum alloy was butt-welded by bobbin tool friction stir welding,and the effect of heat input on formation and mechanical properties were investigated. The results showed that the welded joints was consisted of heat affected zone( HAZ),thermal mechanically affected zone( TMAZ) and weld nugget zone( WNZ). The total amount of plasticized materials and volume of squeezing die determined the morphology of the welded joint. If WP≤1,the amount of plasticized materials is the main influence factor,and the morphology is hourglass shaped. With the decreasing of the heat input,the interface of weld seam and the BM becomes flat gradually,and tunnel defect forms at the advancing side( AS). The tensile strength increases initially and then decreases with the decrease of heat input. When WP > 1,The volume of the squeezing die became the main influence factor,and the interface of weld seam and the BM keeps flatness. No tunnel defect is observed.The tensile strength increases with the decrease of heat input. Lazy S feature forms at the intersection of plasticized materials flow. Heat input affects the morphology of the lazy S through influencing the materials flow. Lazy S feature has little influences on the tensile properties of the joints.