Q&P钢热处理过程有限元法数值模拟模型研究

Modelling of Q&P Steel Heat Treatment Process Based on Finite Element Method

以国内典型淬火-分配(Q&P)高强钢--QP980钢为例,进行热处理全过程物理模拟研究,提出一种耦合温度及时间影响的类蠕变应变方程用以描述材料在Q&P热处理分配过程的体积变化,建立考虑淬火温度影响的Q&P热处理两次淬火过程相变动力学方程、相变应变及相变塑性方程,获得了Q&P钢各相的热膨胀系数。根据温度场、组织场、应力场三场耦合原理,基于物理模拟得到的弹塑性增量本构模型,对商业有限元软件ABAQUS用户子程序进行二次开发,建立了针对Q&P热处理全过程的三场耦合数值仿真模型;通过Gleeble热-力模拟试验机上的Q&P热处理实验对模型进行了实验验证,实验结果与数值模拟结果吻合良好。

Quenching and partitioning(Q&P) steel is a kind of high strength and toughness steels which has a majority of martensite at room temperature and a certain amount of retained austenite through the quenching and carbon distribution heat treatment process of cold-rolled carbon-siliconmanganese steel. In this work, the typical Q&P high-strength steel, QP980 steel, is taken as an example to carry out the physical simulation study of the whole process of heat treatment. A creep-like strain equation coupled with temperature and time is proposed to describe the volume change of materials during Q&P heat treatment. The phase transformation kinetics equation, phase transformation strain and phase transformation plasticity equation of Q&P heat treatment with the influence of quenching temperature were established, and the thermal expansion coefficient of each phase of Q&P steel was obtained. According to the coupling principles of temperature, microstructure and stress-strain field, a numerical simulation model for the whole process of Q&P heat treatment was developed. In this model, the physical simulation of QP980 steel thermal-elastoplastic incremental constitutive equations are imple-mented to commercial finite element software ABAQUS as the user subroutines. The model was validated by Q&P heat treatment experiment on Gleeble thermal-mechanical simulator. The calculated values of the models are both in good agreement with the experimental values.