基于CPFEM构建考虑板条结构的P92钢蠕变力学模型

Construction of P92 steel creep mechanics model considering lath structure based on CPFEM

P92钢在服役过程中,热不稳定性会导致微观组织结构演化,会影响力学性能而降低服役寿命。基于晶体塑性理论和耦合位错动力学方程,引入位错硬化模型和尺寸硬化模型,建立了考虑板条尺寸效应和位错硬化效应的蠕变力学本构模型。将用户材料子程序嵌入到有限元软件ABAQUS中运行,结合Voronoi图形原理生成含有板条结构的代表性体单元(representative volume element, RVE)模型,对P92耐热钢高温蠕变拉伸过程进行模拟。将蠕变模拟结果与试验结果进行匹配,分析了网格单元数量和参数对蠕变模拟结果的影响,确定了蠕变模型的计算参数。RVE模型的应力应变分布表明:蠕变拉伸后P92钢出现不均匀塑性变形。

In the service process of P92 steel, thermal instability will lead to the evolution of the microstructure, which in turn affects the mechanical properties and reduces the service life. Based on the theory of crystal plasticity and coupled with the dislocation dynamics equation, this paper introduces a dislocation hardening model and a dimensional hardening model, and establishes a creep mechanics constitutive model that considers the slab size effect and the dislocation hardening effect. The user material subroutine is embedded into the finite element software ABAQUS to run and combine with the Tyson polygon principle to generate a representative volume element model(RVE) containing a slat structure, and the high temperature creep stretching process of P92 heat-resistant steel is simulated. The creep simulation results are matched with the experimental results, the influence of the number of mesh elements and parameters on the creep simulation results are analyzed, and the calculation parameters of the creep model are determined. The stress and strain distribution of the RVE model shows that the P92 steel after creep stretching uneven plastic deformation occurs.