(钢铁研究总院 先进钢铁流程及材料国家重点实验室，北京100081)
摘 要: 在ER2319焊丝的基础上，分别添加少量Ce、Cr及Mn元素制备了3种焊丝。采用光学显微镜、扫描电镜和能谱分析技术研究微量元素Ce、Cr和Mn对MIG焊缝组织和性能的影响。结果表明：Ce能够细化二次枝晶间距，但Ce易与Ti、Zr相互反应在晶界生成块状硬而脆的AlCuCeTiZrV复杂金属间化合物，降低了Ti和Zr的异质形核作用，使焊缝组织成柱态。而Cr和Mn则能促进Al3Ti、Al3Zr以及复合析出物Al3(Zr, Ti)的析出，增加这些颗粒在高温条件下的稳定性，能够显著细化焊缝晶粒和晶界共晶相，提升接头的力学性能。但Mn的含量达到0.58%时，焊缝中心容易形成粗大树枝晶。
关键字: 高强铝合金；微量元素；形核；等轴晶
（State Key Laboratory of Advanced Steel Processes and Products, Centre Iron & Steel Research Institute, Beijing 100081, China）
Abstract:On the basis of ER2319 filler wire, three filler wires were prepared by adding Ce, Cr and Mn elements. The effects of these trace elements on the microstructure and mechanical properties of MIG welds were investigated by optical microscopy, scanning electron microscopy and energy dispersive spectrum. The results indicate that the addition of Ce can refine the second dendrite arm spacing, but it is easy to form AlCuCeTiZrV complex intermetallic compound at the grain boundary, which will reduce the refinement efficiency of the Ti and Zr inoculants, and make the morphology of the welds microstructure to be columnar. Cr and Mn are proved to improve the refinement efficiency of the Ti and Zr inoculants by increasing the precipitation of Al3Ti, Al3Zr and Al3(Zr, Ti) particles and the stability of these particles under high temperature conditions, which will result in the finer grains and eutectic phase in weld centre and the higher mechanical properties of the welds. When the amount of Mn is 0.58%(mass fraction), the coarse dendrite grains form in the weld centre.
Key words: high strength aluminum alloy; trace elements; nucleation; equiaxed grain
