Development And Application Of Dynamic Soft Reduction System For Continuous Slab

During the solidification the slab is easy to form defects such as center segregation and center porosity, which will lead to a series of steel quality issues, such as steel ductility, weldability, resistance to hydrogen induced cracking and so on. As the increasing quality requirements to slab by users, center segregation and center porosity have become important constraints in production of high-end products. and it was found through experiment and research found that the dynamic soft reduction technology has a very significant effect to reduce even eliminate the center segregation and center porosity of slab, causing people’s concern and attention, the technology has become one of significant marks for modern continuous casting machine.On the basis of past experience in the design and demands in production of continuous casting machines, this paper features the operation of continuous casting machine with soft reduction, the control mode of segment and the relationship between them in detail. A simple, accurate and feasible method for zero calibration has been designed according to the features of hydraulic clamping Segment and production requirement and proven effective in a commercial caster of Chongqing Iron & Steel Group Co., Ltd. After a comprehensive analysis on the basis of relevant information at home and abroad with past experience, the mechanism is derived and the calculations are repeated to determine the optimum reduction parameters for different steel grades and successfully applied to production practice. A new design of mold in upper and lower narrow sides for continuous casting machine based on past experience and user feedback is proposed. a metallurgical database is established after a systematic analysis of the thermal parameters for typical steel grades.A concept of using dynamic slicing to track and simulate the strand in process of continuous casting is proposed, and the enthalpy drop is used to solve the problem of latent heat loss, which was easily caused in calculations of temperature field in the past, processing method of the thermal parameters of steel is explained. According to this problem, the specific implementation of the algorithm and convergence performance was studied, and the results of optimization were tested and evaluated. a software for temperature field of slab solidification has been developed on the basis of the above work, and the program structure for heat transfer model of temperature field in slab casting is optimized and so the program execution time is less than 0.2 seconds and achieved real-time tracking of the slab solidification to provide the foundation for the model of roll gap adjustment.A roll gap adjustment model has been developed. And to ensure the stability of production and product quality, reduction amount is calculated on the revisions to the stability, security value and entrance taper correction. In order to simplify the electrical control, ideas and methods of roll gap value in combination with action order of Segment were proposed and realized, this also ensures that each cycle of roll gap can be adjusted in place in time. As for the case that segment load in production may be too large, there are two ways, reduction region moving forward and automatically reducing reduction amount, can be used according to a range of different conditions, which can not only protect the equipment so that production can be normal, but also provide a means for debugging of the new steel grades.This system has been put into Industrial application in No. 2 Continuous Caster of Chongqing Iron & Steel Group more than two months. Through the low times of sampling inspection, the Centre segregation of slab has been to C-level, significantly improved the internal quality of continuous casting slab, creating a certain economic benefits.In conclusion, the process parameters and model of dynamic soft reduction and the principles of its provisions in this research and development can better guide and resolve the emerging issues in slab continuous casting, and provide a basis and reference for the design of a new continuous casting machine, meanwhile it provides an important theoretical basis and technical approach for domestic independent research and development of soft reduction technology for continuous casting.