Numerical Simulation Of Solidification And Rolling Process Of The Steel Ingot And Its Design Optimization

Mold casting is a traditional process for steel ingot production.Although there are disadvantages such as low yield rate,large loss of steel ingot molds,and many internal defects of steel ingot,mold casting is still widely used in special steelindustry due to the incomparable advantages over continuous casting in handling special alloys and heavy steel ingot.The production equipment of a domestic special steel plant is undergoing transformation and upgrading,therefor it is required to design new ingots to match the equipment.Since the steel ingots produced by special steel plant are to be rolled subsequently,in addition to the section size,mold-ingot ratio,taper,and cap-ingot ratio,it is also necessary to consider the rolling process while designing and optimizing the ingot shape and ingot mold,such as the maximum roll opening,roll pass width,number of roll pass,rolling reduction,roller mill width,the steel turning device before and after the rolling mill,the rolling mill bed,and the size of the soaking furnace,etc.In this paper,three types of ingots were designed according to the requirement:large,medium and small.The design of large ingots was difficult due to the limitation of rolling mills,which is usually not fully considered in the current research.Due to the large section size of the large ingot,a powerful rolling mill with large openings and large deformation and a large motor were required.The 3.2t square ingot,4.8t square ingot,and 8.4t rectangular ingot were modeled by Solidworks.The pouring and solidification process of steel ingots under different parameters were simulated by Any Casting to analyze the central temperature field during the steel ingot solidification process and the internal defects after solidification.The first rolling process of the 8.4t large steel ingot which is difficult to achieve was simulated by Deform and a more reasonable first roll pass was selected to verify the rationality.The results show that during the solidification process of the 3.2t square ingot,the casting head is well capable in heat preservation,and the internal defects are less.The rolled products meet the production quality requirements and the design is reasonable;during the solidification process of the 4.8t square ingot,the feeding ability of the casting head is poor,and the defects locates in the center of the steel ingot,which affects the quality of the final product and the design should be optimized;the taper and section shape are optimized separately,and the internal quality is increased after the taper is increased to 3.5% and 5%,but the total setting time is extended by 0.29 h at 5% taper,so 3.5% taper is more reasonable;after replacing 4.8t square ingot with 5.6t rectangular ingot,the internal defects almost disappear after solidification;the solidification process of 8.4t rectangular ingot is similar to that of 5.6t rectangular ingot,and the internal defects are also less after solidification,indicating that the design of small,large and optimized medium-sized steel ingots are all reasonable,which can ensure product quality,and the result of rectangular ingots is better than square ingots.According to the results of the rolling simulation,it is appropriate to select roll pass with large width for the first pass;for the last few passes,it is better to select roll pass which is contact to the workpiece.In addition,the surface of the rolled piece with convex shape is more favorable to the rolling process.