Numerical Simulation Of Solidification Structure And Thermal Cracking Tendency Of S30432 Continuous Casting Stainless Steel Billet

S30432 high-temperature stainless steel,due to its excellent high-temperature mechanical properties,corrosion resistance and low cost,has become the material of choice for supercritical units in the superheating,reheating and other pipelines.The use of continuous casting technology for the production of S30432 steel can greatly improve the production efficiency and market competitiveness of enterprises,however,the use of vertical bending continuous casting and rolling technology for the production of S30432 heat-resistant stainless steel cast billet after hot perforation to obtain the barren pipe,its quality pass rate is less than 50%,the production of subsequent products and the use of a severe impact.This study focuses on the actual production conditions at Shanxi TISCO Stainless Steel Co.,Ltd.Through the utilization of UG and Pro CAST casting software,a solidification heat transfer model for S30432 heat-resistant stainless steel vertical bent continuous casting billets was established.Steady-state simulations of the continuous casting process were conducted to investigate the influence of process parameters on the solidification process of the billets.With an increase in drawing speed and pouring temperature,the temperature at the billet’s central position rises,leading to a decrease in the solid phase rate.Furthermore,the length of the liquid phase cavities increases,while the thickness of the billet shell decreases.The paste zone experiences backward extension along the casting direction,resulting in an elongated paste zone.The solidification structure of continuous casting billets was simulated using CAFE and microstructure growth was obtained.The effects of different nucleation undercooling,nucleation density,casting speed and pouring temperature on billet microstructure were investigated.The results show that as the nucleation undercooling increases,the average grain radius of the billet increases while the equiaxed grains decrease;as the nucleation density increases,the average grain radius decreases and the proportion of equiaxed grains increases;as the casting speed increases,the number of grains in the cross section of the billet increases,the average grain radius decreases and the grains gradually refine;as the pouring temperature increases,the average grain radius increases,the equiaxed grains decrease and the columnar grains increase significantly.The HCS module was used to calculate the hot crack sensitivity of continuous cast billets and to analyze the effects of different process parameters on the hot crack sensitivity of S30432steel.The RDG criterion is used to predict the evolution of hot cracking in the slab.Under different casting speeds and pouring temperatures,the HCS value of the hot cracking sensitivity of the slab reaches 10¹⁰ and cracks will inevitably occur.The areas prone to cracking are mainly concentrated in the center of the slab.Increasing the casting speed and pouring temperature can effectively reduce the areas of high hot cracking sensitivity in the slab.