Method Of Thermo-mechanical Simulation And Visualization Of Continuous Casting Slab

The complicated behaviors such as fluid flow,solute redistribution,heat transfer,and stress behavior during the solidification process of molten steel in the mold can cause various defects of the continuous casting slab.The research on the thermo-mechanical behavior in the mold is an effective way to solve these defects in the slab.However,it is extremely difficult to conduct a full-scale physical experiment due to the temperature and stress measurement obstacles in high-temperature conditions.In this view,the present work aims to study the numerical calculation and visualization method of the slab thermo-mechanical behavior,which includes the following contents:Firstly,a heat transfer model and a thermo-elasto-viscoplasticity stress model of the slab are established according to the characteristics of continuous casting process.The enthalpy method is introduced to solve the non-convergence problem in calculation caused by the latent heat released from liquid-solid phase transition.Then,the Finite Element Method(FEM)heat transfer calculation model is developed using the weighted residual method,which is served as a prerequisite for stress calculation.After that,a thermo-elasto-viscoplasticity model is established based on a two-dimensional plain stain assumption,considering the effects of thermal shrinkage,elastic deformation,plastic deformation,and creep on the mechanical behavior of the slab.Based on the mathematical model,the designed program for FEM thermomechanical calculation of continuous casting slab is developed by C++ language,which provides a reliable means for studying heat transfer,solidification,and mechanical behavior of the slab in the mold region.Secondly,the slab with a size of 2300 × 220 mm produced by a domestic steel plant is chosen as the research object.According to the measured data of the thermocouple in the mold,non-uniform boundary conditions obtained by the inverse problem algorithm are used to calculated and discussed the heat transfer and shell growth characteristics of the slab.Based on the results of thermal calculation,the mechanic distribution of slab wide face is calculated and analyzed.By analyzing the non-uniformity and excessive differences of the thickness,and stress/strain distribution in the off-corner region,the dominant factors of cracks formation near the corner are discussed.Finally,on the basis of FEM thermo-mechanical calculation program,an object-oriented visualization system for continuous casting is developed using OpenGL graphics technology.Three-dimensional graphics intuitively shows the distribution of the physical field of the slab and mold using the smooth coloring mode and depth testing function.Moreover,through message processing in response to keyboard and menu operations,users can control graphic model rotation and rendering to observe physical field distribution at any position in the slab.In this way,it is convenient to understand the solidification process of the casting slab in the mold,which provides reference and technical support for the improvement of the visualization level of continuous casting process and the control of product quality.