A New Microstructure-Sensitive Flow Stress Model for the High-Speed Machining of Titanium Alloy Ti-6Al-4V
A New Microstructure-Sensitive Flow Stress Model for the High-Speed Machining of Titanium Alloy Ti-6Al-4V
复制标题
钛合金Ti-6Al-4V高速加工的新型微观结构敏感流变应力模型
DOI：
10.1115/1.4035037
复制
发表时间：
2017
影响因子：
4
通讯作者：
Srivastava A. K.
中科院分区：
文献类型：
--
作者：
Zhang X. P.;Shivpuri R.;Srivastava A. K.
钛合金高速加工中的流动应力很大程度上取决于材料的微观组织状态，而微观组织状态是由材料的组成、材料的初始微观组织以及加工过程中施加的热机械载荷所决定的。过去，研究人员根据经验将流变应力确定为应变、应变速率和温度等力学状态参数的函数，而忽略了相变等微观组织状态的变化。本文提出了一种考虑化学成分、α相和β相以及施加的力学状态影响的基于自一致法（SCM）的微结构敏感流变应力模型。该流动应力用于模拟钛合金在高于5m /s的加工速度下的流动行为，其特征是极高的应变（2-10或更高）、高应变率（104 - 106 - 1或更高）和高温（600-1300°C）。分析了流变应力对力学参数和材料参数的敏感性。提出了一种新的基于SCM的Johnson-Cook （JC）流动应力模型，该模型的常数和范围是根据文献中的实验数据和SCM方法的物理基础确定的。在有限元框架中成功地实现了这种新的流动应力来模拟加工。预测结果表明，该模型在预测Ti-6Al-4V钛合金高速加工切屑分割方面比原有的JC模型更加有效和可靠。
The flow stress in the high-speed machining of titanium alloys depends strongly on the microstructural state of the material which is defined by the composition of the material, its starting microstructure, and the thermomechanical loads imposed during the machining process. In the past, researchers have determined the flow stress empirically as a function of mechanical state parameters, such as strain, strain rate, and temperature while ignoring the changes in the microstructural state such as phase transformations. This paper presents a microstructure-sensitive flow stress model based on the self-consistent method (SCM) that includes the effects of chemical composition, α phase and β phase, as well mechanical state imposed. This flow stress is developed to model the flow behavior of titanium alloys in machining at speed of higher than 5 m/s, characterized by extremely high strains (2–10 or higher), high strain rates (104–106s−1or higher), and high temperatures (600–1300 °C). The flow stress sensitivity to mechanical and material parameters is analyzed. A new SCM-based Johnson–Cook (JC) flow stress model is proposed whose constants and ranges are determined using experimental data from literature and the physical basis for SCM approach. This new flow stress is successfully implemented in the finite-element (FE) framework to simulate machining. The predicted results confirm that the new model is much more effective and reliable than the original JC model in predicting chip segmentation in the high-speed machining of titanium Ti–6Al–4V alloy.