2A14-T4铝合金厚板搅拌摩擦焊接头微观组织和力学性能

Microstructure and mechanical properties of friction stir welded joint of 2A14-T4 aluminum alloy thick plate

随着工业技术的进步,航空航天、交通运输等领域对构件的承载能力提出了越来越高的需求,采用搅拌摩擦焊的方法对9 mm厚2A14-T4铝合金进行连接,并对高强铝合金厚板接头沿厚度方向不同区域的微观组织和力学性能进行研究.结果表明,在转速400 r/min、焊接速度100 mm/min条件下能够获得表面成形良好的焊缝,接头抗拉强度为360 MPa,达到母材强度的83.9%.接头微观组织沿厚度方向存在显著差异,焊缝上部、中部、下部晶粒尺寸逐渐减小,其平均直径分别为7.9,5.0和2.8μm.焊缝底部断口出现小而浅的等轴状韧窝.接头断裂位置和最低显微硬度均出现在接头后退侧的热力影响区;同时接头显微硬度呈现“W”形分布,且沿厚度方向分布存在差别,焊缝上部、中部、下部显微硬度最低值分别为99.9,97.9和94.7 HV.

With the progress of industrial technology,aerospace, transportation and other fields put forward higher and higher demand for the bearing capacity of components. In this paper, friction stir welding method was used to join 9 mm thick 2A14-T4 aluminum alloys.The microstructure and mechanical properties of high strength thick aluminum alloy plate joints along the thickness direction were studied. The results indicate that the butt joint has good appearance at the rotating speed of 400 r/min and the welding speed of 100 min/min, and the tensile strength of the joint is 360 MPa, which is 83.9 % of the base metal. There are significant differences in the microstructures of the joint along the thickness direction. The average grain diameters of the top, middle and bottom of the weld are 7.9, 5.0 and 2.8 μm, respectively. The dimples at the bottom of the joint are equiaxed, with small diameter and shallow depth. The fracture position and the minimum microhardness of the joint appear in the thermo-mechanically affected zone of retreating side. The microhardness of the top, middle and bottom of the weld are 99.9, 97.9 and 94.7 HV, respectively.