大型筒节轧制成形工艺的数值模拟与试验研究-材料加工工程专业论文.docx

机械 机械科学研究总院硕士学位论文 万方数据 万方数据 ABSTRACT Heavy shell is one of the key components in heavy pressure vessels, hydrogenation reactor and coal liquefaction reactor in the field of nuclear power, petrochemical and coal chemical equipment. Generally, heavy shell is used for bear pressure and it works at high temperature and corrosive environment for long-term. Free forging is the traditional process to produce heavy shells, however because the material utilization and productivity in free forging are low, heavy shells are facing difficulties in short supply. In this paper, the rolling forming process of heavy shell based on rolling was studied. The main contents are as follows: Isothermal compression experiments were carried on 2.25Cr1Mo0.25V steel. The law between flow stress and deformation temperature and strain rate were obtained. The results showed that dynamic recrystallization was prone to occur at high temperature and low strain rate. It could be obtained through metallurgical experiments that as the deformation temperature increased, the average grain size increased, but the grain distribution was more uniform. As the strain rate increased, the average grain size decreased, but the grain distribution was less uniform. Based on Avrami equation, mathematical model of dynamic recrystallization for 2.25Cr1Mo0.25V steel was established combining with isothermal compression experiments and metallographic experiments. This model was imported into Deform software to simulate the dynamic recrystallization of hot compression, which verified the mold was correct. The heavy roll size is ?5258mm×?4086mm×3080mm. Rolling process simulation was established using Deform-2D finite element platform, which was used to investigate the effects of rolling temperature, feed velocity, deformation degree and angular velocity. The results showed that rolling temperature exerted the most important effect on rolling force and average grain size. The second was deformation degree and angular vel