Flow behavior and constitutive description of 20CrMnTi steel at high temperature

Abstract

In order to research the flow behavior of 20CrMnTi and obtain its constitutive equation, the isothermal compression tests of 20CrMnTi were carried out using the Gleeble—3500 thermo-simulation machine, up to a 60% height reduction of the sample at strain rate range from 0.01 s⁻¹ to 10 s^–1 and deformation temperature range from 1123 K to 1273 K. According to the experimental results, the constitutive equation of 20CrMnTi was established based on Arrhenius model. In addition, the compensation of strain was taken into account and a new method of modifying the constitutive equation was proposed by introducing a coefficient K related to the deformation temperature and stain rate, which effectively improved the prediction accuracy of the developed constitutive equation. The results show that the flow stress decreases with increasing deformation temperature and decreasing strain rate, and the proposed constitutive equation well predicts the flow stress of 20CrMnTi during the high temperature deformation.

摘要

为了研究20CrMnTi 的高温流变行为,获得其高温状态下的本构方程,在Gleeble–3500 热模拟 试验机上进行了20CrMnTi 的等温压缩试验。试样压缩量为60%,应变速率从0.01 s^–1 到10 s^–1,热变 形温度范围为1123 K 到1273 K。根据试验结果,基于阿伦尼斯模型建立了20CrMnTi 的本构方程。 为了进一步提高模型的精度,考虑到应变的影响提出了一种新的建立方法。引入了一个和变形温度和 应变速率相关的系数K 对模型进行了修**,修**后的模型精度得到有效的提高。根据结果发现,随着 变形温度的升高和应变速率的降低,流变应力降低。结果表明:采用新方法建立的本构方程可以有效 预测20CrMnTi 高温变形的流变应力,提高模拟的精度。