电子束扫描波形对铝锂合金显微组织及力学性能的影响

对厚度1.8 mm的2198-T8态铝锂合金薄板进行真空电子束焊接,分析了不同扫描方式对焊缝成形及接头力学性能的影响,以及最优焊接工艺下焊接接头的显微组织与力学性能。结果表明:在工作距离为300 mm、加速电压U=60kV、聚焦电流I_f=498 mA以及电子束流I_b=6.8mA情况下,不添加扫描可获得成形良好且无宏观气孔缺陷的焊接接头。相同参数条件下对比添加了扫描方式的焊接,得出焊接过程中添加三角波扫描时,焊缝的显微硬度值和焊接接头的抗拉强度均得到了提高,焊接接头的平均抗拉强度为326.5 MPa,其中最高抗拉强度可达到母材的71.5%,延伸率最高可达母材延伸率的86.8%,焊缝熔合区较整个焊缝区来说最为薄弱。

Effect of scanning mode on Microstructure and mechanical properties of 2198 Al-Li alloy joint fabricated by electron beam welding

Aluminum lithium alloy is considered to be one of the ideal materials for lightweight structural materials in the aerospace field. The 2198-T851 aluminum lithium alloy 1.8 mm thickness sheet of vacuum electron beam test,analysis the different scanning modes on weld forming and the influence of mechanical properties of joints, and under the optimal welding process welding joint microstructure and mechanical properties. The results show that the working distance is 300mm, the acceleration voltage is U=60kV, the focusing current is I_f=498mA ,the welding speed V=1200mm/min and the electron beam is I_b=6.8mA, the welding joint without the addition of scanning can obtain good forming and no macro porosity defects.Under the same conditions compared to other add scan mode of welding, derived welding in the process of adding triangle wave scanning, we can not only obtain the forming good macro porosity defects in the welded joints, and the welding joint of the hardness values and tensile strength is improved. The average tensile strength of welded joint is 323.55MPa, and the fracture strength of the joint is 71.5%, The extension rate is up to 86.8% of the elongation of base metal.which is the weakest part of the weld zone.