中文摘要：

以Ti60高温钛合金为研究对象,提出一种采用高速摄影技术来确定钛合金热压缩过程中临界开裂应变的新方法,该方法通过采用2个对称分布的高速摄影仪来准确捕获裂纹形核的位置以及裂纹扩展路径,可成功地获得热变形过程中的临界开裂应变。最终基于Oh准则,通过引入Zener-Hollomon因子,建立了可以考虑温度和应变速率综合影响的Ti60钛合金热变形的韧性开裂准则。采用FORTRAN语言二次开发子程序将热变形开裂准则嵌入商用有限元软件DEFORM-3D中,对大规格Ti60合金铸锭热镦开裂行为进行预测,验证了模型的有效性。

英文摘要：

A novel high-speed photography was introduced to determine the critical fracture strain of Ti60 high-temperature titanium alloy during hot compression deformation. This method can precisely capture the nucleation site and propagation process of cracking by two high-speed cameras fixed on opposite sides of the specimens, and thus it is efficient to determine the critical fracture strain in hot deformation processes. Based on Oh criterion, a new hot deformation fracture criterion considering strain rate and temperature effects was built and can be modeled as the function of Zener-Holloman parameter. By combining the DEFORM-3D simulation software and FORTRAN language, fracture initiation in the upsetting of large size Ti60 ingot can be precisely predicted, which shows that the proposed prediction model is effective and practicable.