2219铝合金双轴肩搅拌摩擦焊工艺及接头组织性能研究

通过对8mm厚2219铝合金进行双轴肩搅拌摩擦焊试验,研究了不同焊接速度对接头成形、组织演变及其对力学性能的影响规律。工艺试验结果表明:在固定转速(200r/min)下,不同焊接速度下的接头均成形良好,未出现微裂纹、隧道以及疏松等焊缝表面缺陷。随着焊接速度的增加,接头区域晶粒尺寸减小;接头显微硬度受到晶粒尺寸与沉淀相分布的制约,硬度分布曲线呈“W”形,热影响区硬度最低。并且随着焊接速度的增加,接头最低硬度和抗拉强度逐渐提高,断裂位置发生在热影响区与热影响区交界处。在焊接速度为350mm/min时,接头抗拉强度达到最大值335MPa,约为母材的72.8%。

Research on Welding Process and Joint Microstructure-properties of Bobbin Tool Friction Stir Weld for 2219 Aluminum Alloy

Bobbin tool friction stir welding of 8 mm thick 2219 aluminum alloy sheets is carried out, and the influence of welding speed on the microstructure and mechanical properties of the welded joints are investigated. The results show that at the rotational rate is 200 r/min, sound joints can be obtained under the various welding speeds. As the welding speed increases, the heat input decreases,so that the size of the recrystallized grains gradually decreases. The hardness change of 2219 aluminum alloy can be attributed to the distribution of precipitates phase particles and the heterogeneity of grains. The lowest hardness zones are located at the heat-affected zones of the joint. With the increase of welding speed, the lowest hardness and tensile strength of the welded joints increase gradually.The welded joints fracture in the boundary of the HAZ and TMAZ. When the welding speed is 350 mm/min, the tensile strength reaches the maximum value of 335 MPa, which corresponds to 72.8% of that of the base metal.