Ti555211钛合金片层组织拉伸过程裂纹扩展的SEM原位观察

In-situ SEM Observations on Tensile Deformation Behavior of Ti555211 Titanium Alloy with Lamellar Structure

利用SEM原位拉伸实验,研究了Ti555211钛合金片层组织的拉伸变形和断裂行为。结果表明:在拉伸载荷作用下,滑移带优先出现在与加载方向大于45°的片层组织上。在裂纹扩展过程中,滑移带的密度均随着载荷的增加逐渐增大,为沿片层和跨片层交叉断裂。原位拉伸试样断口分析表明,韧性断裂是片层组织试样的主要断裂方式。试样断口存在明显剪切唇和大量断裂韧窝。SEM原位拉伸实验分析方法能够对新型Ti555211近β钛合金的变形和断裂行为进行实时跟踪,该方法的研究结果具有科学价值和参考意义。

The tensile deformation and fracture behavior of Ti555211 alloy were investigated by in-situ SEM tensile tests. The results show that the slip bands are given priority within the lamellar structure with the tensile loading direction larger than 45° for the Ti555211 alloy with initial lamellar structure. The cracks propagate from the corners of the indention both across and along the lamellar directions for the alloy with initial lamellar directions. Moreover, as the crack propagates, the slip bands become dense. The main fracture mode of the lamellar samples is ductile fracture. The Ti555211 alloy shows different fracture morphologies. For the alloy with initial lamellar structure, visible shear lips and a number of dimples are observed in the fracture. The deformation and fracture behavior of the near-βtitanium alloy of Ti555211 can be tracked by the SEM in-situ tensile test method in real time. The results of this method are scientific and informative.