搅拌摩擦焊工艺参数对2198铝锂合金焊缝成形及接头力学性能的影响

对2198铝锂合金薄板进行了搅拌摩擦焊试验,分析了搅拌头旋转速度和焊接速度对焊缝成形及接头力学性能的影响。结果表明:旋转速度(n)与焊接速度(v)的比值大于15.7时,能形成表面成形良好,且内部致密无缺陷的焊缝;接头焊核区形成了细小的等轴晶,前进侧热力影响区大部分为等轴状晶粒,后退侧热力影响区的板条状组织发生了变形,其周围出现了细晶粒;焊接速度为30mm·min-1时,接头的抗拉强度随旋转速度的增大而变小,其最大值为432.17MPa,焊缝的硬度低于母材的,热力影响区的硬度最低,焊核区的硬度略高于热力影响区的。随着n/v的增大,热影响区的软化区间变宽。

Effects of Friction Stir Welding Process Parameters on Welded Seam Forming and Mechanical Properties of Welded Joint for 2198 Al-Li Alloy

The friction stir welding test was performed on 2198 Al-Li alloy sheet,and the effects of rotation rate and welding rate of friction stir tool on welded seam forming and mechanical properties of welded joint were analyzed.The results show that when the ratio of rotation rate to welding rate was more than 15.7,a compact welded seam with good forming surface and free of defects was obtained.The microstructure in nugget zone was fine equiaxed grains,and the microstructure of heat-mechanical affected zone at advancing side was almost small equiaxed grains,and the lath structure of heat-mechanical affected zone at the retreating side deformed,there were small grains around the lath microstructure.The tensile strength of the joints decreased with the increase of rotation rate when the welding rate was 30 mm·min-1,and the maximal tensile strength was 432.17 MPa.The hardness of the welded seam was lower than that of the base metal,and the hardness of nugget zone was little higher than that of heat-mechanical affected zone,and the hardness of heat-mechanical affected zone was the lowest.The softened range of heat affected zone became wider with the increase the ratio of rotation rate to welding rate.