(中國工程物理研究院 機械制造及工藝研究所，綿陽 621900)
摘 要: 對10 mm厚的2A14鋁合金板進行電子束焊接，通過金相及掃描電鏡沿焊縫熔深方向?qū)Ω鱾�區(qū)域的微觀組織進行對比分析。結(jié)果表明：電子束焊接2A14鋁合金接頭沿焊縫中心和焊縫邊緣的組織在尺寸、結(jié)晶形態(tài)和生長方向上存在很大差異，焊縫頂部和根部的組織尺寸較粗大，晶粒尺寸可達到20~50 μm，靠近熔合線附近的焊縫組織沿最快散熱方向具有明顯的方向性，焊縫中心部位的組織非常細小，晶粒尺寸小于10 μm，分布均勻，呈典型的非平衡快速凝固形成的枝晶組織。焊縫根部容易形成縮孔并伴隨裂紋的產(chǎn)生，可通過散焦焊接和焊后背部重熔的方法加以消除。
關(guān)鍵字: 2A14鋁合金；電子束焊接；微觀組織；縮孔
（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
