Numerical Simulation And Experimental Research On Rolling Of Heavy Shell

Heavy shell is one of the key components in heavy pressure vessels, hydrogenationreactor and coal liquefaction reactor in the field of nuclear power, petrochemical and coalchemical equipment. Generally, heavy shell is used for bear pressure and it works at hightemperature and corrosive environment for long-term. Free forging is the traditional processto produce heavy shells, however because the material utilization and productivity in freeforging are low, heavy shells are facing difficulties in short supply. In this paper, the rollingforming process of heavy shell based on rolling was studied. The main contents are asfollows:(1) Isothermal compression experiments were carried on2.25Cr1Mo0.25V steel. Thelaw between flow stress and deformation temperature and strain rate were obtained. Theresults showed that dynamic recrystallization was prone to occur at high temperature and lowstrain rate. It could be obtained through metallurgical experiments that as the deformationtemperature increased, the average grain size increased, but the grain distribution was moreuniform. As the strain rate increased, the average grain size decreased, but the graindistribution was less uniform.(2) Based on Avrami equation, mathematical model of dynamic recrystallization for2.25Cr1Mo0.25V steel was established combining with isothermal compression experimentsand metallographic experiments. This model was imported into Deform software to simulatethe dynamic recrystallization of hot compression, which verified the mold was correct.(3) The heavy roll size is5258mm×4086mm×3080mm. Rolling process simulationwas established using Deform-2D finite element platform, which was used to investigate theeffects of rolling temperature, feed velocity, deformation degree and angular velocity. Theresults showed that rolling temperature exerted the most important effect on rolling force andaverage grain size. The second was deformation degree and angular velocity. The last one isfeed velocity. After analysis, it could be obtained that when rolling were between1150℃and1200℃, deformation degree was60mm and70mm, angular velocity were between0.15374rad/s and0.16374rad/s, the heavy shell formed well, rolling force was small, theaverage grain size was small and distribution was uniform. (4) The grain distribution law was studied in the radial and axial by subscale test. Theresult was consistent with the simulation result. It could be used for predicting the graindistribution of the heavy shell rolling.