核电用钢淬火过程温度场-组织场数值模拟及试验研究

Numerical simulation and experimental study of temperature field and microstructure field during quenching of nuclear steel

为获得SA508Gr.4N钢末端淬火过程中温度场及组织场的变化规律,通过对非线性有限元模拟软件进行二次开发,建立SA508Gr.4N钢末端淬火过程中的温度-组织耦合的有限元模型,并通过实验对数值模拟结果进行验证。研究结果表明:所建立的温度-组织耦合模型计算结果与实验结果吻合良好,温度场的变化主要受综合换热系数影响;组织场模型适用于扩散型和非扩散型相变组织与维氏硬度的预测。随淬火端面的距离增大,试样组织呈现出由完全马氏体相到马氏体+贝氏体混合相的变化,维氏硬度逐渐降低,与温度-组织耦合模型计算得到的组织、硬度变化规律一致,因此,本文所提模型可以用于预测SA508Gr.4N钢末端淬火过程中温度场及组织场变化规律。

In order to obtain the variation law of temperature and microstructure during end quenching of SA508Gr.4N steel,a finite element model of temperature-microstructure coupling during end quenching of SA508Gr.4N steel was established through the secondary development of nonlinear finite element simulation software,and the numerical simulation results were verified by experiments.The results show that the established temperature-microstructure coupling model calculation result is in good agreement with the experimental result,and the temperature field is mainly affected by the comprehensive heat transfer coefficient.The structure field model is suitable for predicting the microstructure and Vickers hardness of diffusive transformation and non-diffusive transformation.The microstructure of experimental sample changes from complete martensitic structure to martensitic+bainite mixed structure with the increase of the distance from the quenched end surface,and the Vickers hardness gradually decreases,which is consistent with the microstructure and hardness change law calculated by the temperature-microstructure coupling model.Thus,the proposed model can be used to predict the temperature field and microstructure field change law during the quenching process of SA508Gr.4N steel.