In situ investigation of the tensile deformation of laser welded Ti2AlNb joints
In situ investigation of the tensile deformation of laser welded Ti2AlNb joints
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DOI：
10.1016/j.matchar.2016.11.009
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发表时间：
2017
影响因子：
4.7
通讯作者：
Kezhao Zhang;Long Ni;Z. Lei;Yan-bin Chen;X. Hu
中科院分区：
文献类型：
--
作者：
Kezhao Zhang;Long Ni;Z. Lei;Yan-bin Chen;X. Hu
采用原位分析方法研究了Ti 2AlNb激光焊接接头的拉伸变形行为。单相B2熔合区的断裂方式在室温下为准解理断裂，650 °C时为沿晶断裂，而母材在室温和650 °C时均为微孔聚结断裂。使用原位SEM拉伸测试观察室温下的拉伸变形。在母材中，微裂纹主要在O相中或沿着O/B2相界形核和扩展。虽然在单相B2熔合区中发现了交叉滑移和多滑移，但使用共聚焦激光扫描显微镜在650 °C下原位观察裂纹萌生和扩展过程。裂纹主要沿着母材中的B2/O相界，沿着熔合区中B2相的脆性晶界形成。热模拟实验和TEM分析表明，Ti 2AlNb激光焊接接头的高温脆性是由连续O相薄膜沿着B2晶界析出所致。
The tensile deformation behavior of laser welded Ti2AlNb joints was investigated using in situ analysis methods. The fracture mode of the single-B2-phase fusion zone was quasi-cleavage at room temperature and intergranular at 650 °C, while that of base metal was microvoid coalescence at both room temperature and 650 °C. Tensile deformation at room temperature was observed using in situ SEM tensile testing. In base metal, microcracks nucleated and propagated mainly within the O phase or along O/B2 phase boundaries. While both the cross- and multi-slips were found in the single-B2-phase fusion zone, a confocal laser scanning microscopy was used to observe the crack initiation and propagation process in situ at 650 °C. Cracks mainly formed along the B2/O phase boundaries in base metal, along the fragile grain boundaries of B2 phase in the fusion zone. The thermal simulation experiment and following TEM analysis indicated that the precipitation of continuous O-phase films along the B2 grain boundaries resulted in the high temperature brittleness of laser welded Ti2AlNb joints.