Mates Steven P, Li Sheng-Yen
National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
J Res Natl Inst Stand Technol. 2021 Oct 27;126:126026. doi: 10.6028/jres.126.026. eCollection 2021.
The National Institute of Standards and Technology (NIST) developed an experimental technique to measure the dynamic flow stress of metals under rapid heating to study their time-dependent plastic response when heating times are short enough to interrupt or bypass thermally driven microstructural evolution. Such conditions may exist as chips are formed in the machining process. Measurements of American Iron and Steel Institute1045 steel behavior up to 1000 °C showed complex thermal softening due to dynamic strain aging effects and the diffusion-limited austenite transformation process beginning at the A1 temperature (712 °C). This paper proposes a constitutive model to capture the flow stress and hardening evolution of 1045 steel under rapidly heated conditions for simulating metal cutting. The model combines the Preston-TonksWallace plasticity model, which uses five parameters to capture complex rate- and temperature-sensitive strain hardening, with a dual-ratesensitivity model to capture the response of rapidly heated 1045 steel. Finally, a strain-rate-dependent Gaussian function is introduced to capture dynamic strain aging effects, which act over a narrow range of temperatures that change with strain rate. The proposed model is compared to existing plasticity models for 1045 steel over the range of data available and at a representative machining condition.
美国国家标准与技术研究院（NIST）开发了一种实验技术，用于测量金属在快速加热下的动态流变应力，以研究在加热时间短到足以中断或绕过热驱动微观结构演变时其随时间变化的塑性响应。在加工过程中形成切屑时可能会存在这种情况。对美国钢铁协会1045钢在高达1000°C的行为进行的测量表明，由于动态应变时效效应以及从A1温度（712°C）开始的扩散限制奥氏体转变过程，出现了复杂的热软化现象。本文提出了一个本构模型，用于捕捉1045钢在快速加热条件下的流变应力和硬化演变，以模拟金属切削。该模型将使用五个参数来捕捉复杂的应变率和温度敏感应变硬化的普雷斯顿 - 汤克斯 - 华莱士塑性模型与一个双应变率敏感性模型相结合，以捕捉快速加热的1045钢的响应。最后，引入了一个应变率相关的高斯函数来捕捉动态应变时效效应，该效应在随应变率变化的狭窄温度范围内起作用。在所获得的数据范围内以及在一个具有代表性的加工条件下，将所提出的模型与现有的1045钢塑性模型进行了比较。
