Analysis And Optimization On Numerical Simulation Of Extrusion Process Of Large-diameter Seamless Steel Tube With Thick Wall

Large-diameter seamless steel tube with thick wall is one of the most important basiccomponents in the thermal and nuclear power equipments. At present the domestic can’t meetthe demand of high temperature resistant large-diameter seamless steel tube with thick wallthat in need of solution in the equipments of super (ultra) critical thermal power of the thirdgeneration. The traditional production technology of seamless steel tube can’t afford thequality requirements. The manufacturers in the domestic that can produce the pipes withstable quality, reliable process stability and are full of experience are seldom, especially forthe high level nuclear power and high-pressure boil tubes that are made of P91 heat resistancesteel of ferrite. In order to solve this problem, we simulated the vertical extrusion process ofP91 large-diameter seamless steel tube with thick wall, and optimized the technology.During the research we had a thermal simulation experiment by GLEEBLE-3500thermal simulation test machine, got the high temperature flow strain-stress curves of P91material, and analyzed the experiment results. The high temperature flow strain-stress wasused as a basic parameter of the numerical simulation.In this research, we used the finite element simulation software of DEFORM-3D tosimulate the vertical extrusion process of the two kinds of typical pipes whose sizes are559mm×339mm×12000mm and 813 mm×679 mm×6500mm. During the research,we changed the numerical values of extrusion ratio, cone angle and sizing belt height.Through the simulation results we analyzed the effection of those parameters on the formingpipes’wall thickness, effective stress, effective strain, temperature and the load of top dieduring the extrusion process.After the analysis of the vertical extrusion processes of the two pipes, we optimized thepipes’forming technologies using the method of neural network combined with geneticalgorithm, and finally determined the best technology to forming the aimed pipes. That arewhen the extrusion is 5.8, the cone angle is 15°and the sizing belt height is 122mm, the pipeof 559mm×339mm×12000mm can form best and when the extrusion is 6.5, the coneangle is 20°and the sizing belt height is 160mm, the pipe of 813 mm×679 mm×6500mmcan form best. All those research can provide certain theoretical analysis basis for practical.