不同焊接速度下2024铝合金搅拌摩擦焊接头的显微硬度与拉伸性能

对5mm厚2024铝合金板进行了不同焊接速度(20～100mm·min-1)下的搅拌摩擦焊,研究了焊接接头的显微硬度与拉伸性能。结果表明:接头在垂直于焊缝方向上的显微硬度整体呈W形分布,焊核区显微硬度高于热影响区与热机影响区的,但仍低于母材的,热影响区和热机影响区过渡位置的显微硬度最低;随焊接速度的增大,焊核区的平均显微硬度升高,焊接接头的抗拉强度和伸长率均呈先增大后略微降低的趋势;当焊接速度为80mm·min-1时,抗拉强度和伸长率均达到最大值,分别为347.2MPa和7.8%;接头在热机影响区与热影响区边界发生剪切断裂,断裂位置与显微硬度最低位置相吻合,接头的断裂方式为韧性断裂。

Microhardness and Tensile Properties of Friction Stir Welded Joint of 2024 Aluminum Alloy at Different Welding Speeds

2024aluminum alloy plate with thickness of 5mm was welded by friction stir welding at different welding speeds(20-100mm·min^-1).The microhardness and tensile properties of the welded joints were studied.The results show that the microhardness of the joint in the direction of perpendicular to the weld showed a W-shaped asymmetric distribution.The microhardness of the weld nugget zone was higher than that of the heat affected zone and the heat affected zone,but still lower than that of the base metal;the microhardness of the transition position between the heat affected zone and the thermo-mechanically affected zone was the lowest.With the increase of welding speed,the average microhardness of the weld nugget zone increased;the tensile strength and elongation of the welded joint increased first and then slightly decreased.When the welding speed was 80mm·min^-1,the tensile strength and elongation both reached the maximum values of 347.2MPa and 7.8%,respectively.The shear fracture of the joint occurred at the transition position between the heat affected zone and the thermo-mechanically affected zone,and the fractured position corresponded well with the position with the lowest hardness.The fracture mode of the joint was ductile fracture.