基于特征点及物理软化参数法的金属热成形本构关系建模研究

项目名称： 基于特征点及物理软化参数法的金属热成形本构关系建模研究

项目编号： No.51304171

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 矿业工程

项目作者： 王健

作者单位： 燕山大学

项目金额： 26万元

中文摘要： 本构模型是进行材料塑性加工的基础，但现有模型中存在如半经验蠕变方程不含应变，基于应变的模型参数众多、物理意义不明确，有非独立参数等问题。 项目将研究建立基于特征点和物理软化参数法、有明确物理意义反映材料内部微观组织演变机理、参数明晰的金属高温热成形本构模型：(1)考虑金属热成形流变应力曲线上特征点出现的微观机理，由应变硬化率与应力的关系出发，建立动态再结晶(DRX)前流变应力关于特征点变量和材料参数的模型；(2)提出已发生DRX晶粒流变应力的概念，构造更具物理意义的DRX软化分数计算式，以位错密度为内部变量，借助其与应力、应变的关系求解DRX后流变应力关于关键特征点变量以及动态回复参数的模型；(3)利用实验曲线，求解特征点变量、动态回复参数、Avrami方程待定参数与Z参数的关系，并进行实验验证。 项目的研究将丰富金属材料热成形及高性能精确制造成形生产控制工艺，为金属热成形生产提供参考。

中文关键词： 本构模型；流变应力；动态回复；再结晶；特征点

英文摘要： Constitutive model is essential in material plastic processing field, but there are some problems in existing models, such as strain is not included in the semiempirical creep equations, multitudinous parameters appear in the model based on strain, the parameters of some models have few definite physical meanings and correlative variables exsit. This project aims at establishing a more physically appropriate constitutive model of metal based on characteristic points and physical softening parameter method during hot forming. The mechanism of microstructure evolution will be reflected by the model. The flow stress could be obtained by the following way. The flow stress before DRX will be got based on the relationship between the flow stress and the rate of work hardening. The characteristic point variables and material parameter are included. The flow stress of dynamic recrystallization(DRX) grains will be used in the modelling of the flow stress after DRX. A new more remarkable physical significances and practically useful fractional softening model is presented for the simulation of high temperature austenite flow curves. General equations describing the flow stress after DRX are derived from the formula that represents the dependence of the dislocation density on plastic strain and stress. It contains the stre

英文关键词： constitutive model；flow stress；dynamic recovery；recrystallization；characteristic point