(中国工程物理研究院 机械制造及工艺研究所，绵阳 621900)
摘 要: 对10 mm厚的2A14铝合金板进行电子束焊接，通过金相及扫描电镜沿焊缝熔深方向对各个区域的微观组织进行对比分析。结果表明：电子束焊接2A14铝合金接头沿焊缝中心和焊缝边缘的组织在尺寸、结晶形态和生长方向上存在很大差异，焊缝顶部和根部的组织尺寸较粗大，晶粒尺寸可达到20~50 μm，靠近熔合线附近的焊缝组织沿最快散热方向具有明显的方向性，焊缝中心部位的组织非常细小，晶粒尺寸小于10 μm，分布均匀，呈典型的非平衡快速凝固形成的枝晶组织。焊缝根部容易形成缩孔并伴随裂纹的产生，可通过散焦焊接和焊后背部重熔的方法加以消除。
关键字: 2A14铝合金；电子束焊接；微观组织；缩孔
（Institute of Machinery Manufacturing Technology, China Academy of Engineering Physics, Mianyang 621900, China）
Abstract:The electron beam welding was performed on 10 mm thick 2A14 aluminum alloy sheets. Metallography and scanning electron microscopy were used to study the weld microstructure. The microstructures of different sites in the weld was employed to compare and analyze the structure distribution in weld-bead. The results show that electron beam (EB) welding 2A14 Al alloy establishes a nonuniform temperature distribution throughout the weld pool and this thermal condition leads to the difference in grain size and solidification mode along the depth of penetration. The up and bottom of the weld-bead are coarse grained region where the crystallite dimension is up to 20−50 μm and the microstructure near bong line is arranged along the solidification direction, while in the middle of the weld-bead, there are fine and homogeneous non-equilibrium microstructures of dendritic grains with dimension of less than 10 μm. Focusing out welding and post welding re-melting were used to remove the shrinkage and associated cracks, which are easy to form in the root of weld.
Key words: 2A14 aluminum alloy; electron beam welding; microstructure; shrinkage
