考虑相变的热弹塑性本构方程及其应用

将在热加工及热处理过程中发生相变的材料考虑为热弹塑性的多相混合物，基于连续介质物理学及含内变量的不可逆热力学，推导出考虑相变的热弹塑性本构方程.根据一组不同温度水平下的高温短时拉力试验，确定本构方程中的材料参数及其随温度的变化关系.同时，提出了考虑相变的热传导方程和计及应力影响的相变动力学方程.基于这些方程编制相应有限元分析程序，用其分析计算了1Cr12WMoV不锈钢管通的焊接残余应力分布.计算所得结果与通过X射线衍射测试的实验结果具有较好的一致性. 关键词： 相变 热弹塑性 本构方程 焊接

A thermo-elastoplastic constitutive equation including phase transformation and its applications

Heat-processed materials undergoing phase transformation are considered to be a mixture of several phases, and each of them possesses thermo-elastoplastic property. A thermo-elastoplastic constitutive equation involving phase transformation is put forward based on the physics of continuous media and the irreversible thermodynamics with internal variables. The material parameters in the constitutive equation and their variations with temperature are determined by a series of short-time-tension tests at different temperatures. The heat conduction equation including phase transformation and the transformation kinetics equation including stresses are also presented. The numerical algorithm and the finite element procedure related to these equations are developed and applied to the investigation of the distribution of the residual stress in the welding slot area of 1Cr12WMoV stainless steel pipe. The obtained results of the residual stress are in good agreement with the measurements by X-ray diffraction.