ABSTRACT

A new characteristic parameter ($T_{\mathrm{M}50}$) is introduced which is defined as threshold temperature below which it is not possible to obtain 50% dynamically recrystallised grains for a given strain rate. This parameter is emerged during analysis of kinetics of dynamic recrystallisation (DRX) by introducing another new parameter. The latter is defined as the maximum possible fraction of dynamically recrystallised grains for a given set of temperature and strain rate. The parameters $X_s$ and $T_{\mathrm{M}50}$ are related through a sigmoidal relationship. Typically, the kinetics of DRX is studied using different forms of Avrami-type equation. In the present investigation, kinetics of DRX is simulated using Logistic model. Unlike Avrami-type models, the mathematical expression for Logistic model does not include exponent. The fitting parameters associated with Logistic model are shown to be connected with the nature of DRX curves and distinct physical interpretation can be given to each parameter. The fitting parameters also exhibit definite mathematical relationship with temperature and strain rate. The strain required for 50% of DRX is shown to have non-linear relationship with inverse of temperature.

摘要

一个新的特征参数（${吨}_{\mathrm{米}50}$) 被定义为阈值温度，低于该温度对于给定的应变速率不可能获得 50% 的动态再结晶晶粒。该参数是在动态再结晶 (DRX) 动力学分析过程中通过引入另一个新参数出现的。后者被定义为在给定的温度和应变速率下动态再结晶晶粒的最大可能分数。参数$X_{秒}$ 和 ${吨}_{\mathrm{米}50}$通过 Sigmoidal 关系相关联。通常，使用不同形式的 Avrami 型方程研究 DRX 的动力学。在本研究中，DRX 的动力学是使用 Logistic 模型模拟的。与 Avrami 型模型不同，Logistic 模型的数学表达式不包含指数。与 Logistic 模型相关的拟合参数显示与 DRX 曲线的性质有关，并且可以对每个参数给出不同的物理解释。拟合参数也表现出与温度和应变率的明确数学关系。显示 50% 的 DRX 所需的应变与温度的倒数呈非线性关系。