Optimization And Research On Production Process Of Automobile Steel In CSP Production Line

Microalloyed steels are widely used in construction machinery,automobiles,shipbuilding,petrochemicals,high-rise buildings and marine engineering,etc.,with a wide range of uses.In recent years,the national key development and revitalization industries have developed rapidly,and the demand for high-quality alloy steel has increased greatly.In order to improve market competitiveness and economic efficiency,and realize sustainable development,enterprises can only unswervingly follow the development path of microalloyed steel.Due to the unique metallurgical characteristics of the CSP thin slab caster,such as high cast speed,strong cooling,and fine structure,the use of CSP process route to produce microalloy steel containing Nb,V has become a new trend in the development of this type of production line.However,in the production process of microalloyed steel,there are frequent transverse cracks in the corners of the cast slab,which severely restricts the high-quality and efficient production of the production line.In this paper,based on the actual production of Nb,V,and B-containing microalloyed steel in the CSP production line of a steel company,the cause of edge cracking of thin slab microalloyed hot-rolled coils is studied.Corresponding solutions are proposed for production equipment,technology,operation,etc.Aiming at the problem that the generation mechanism of microalloyed steel edge cracks is not clear,the mechanism of crack generation is studied through experimental methods such as metallographic microscope,scanning electron microscope and transmission electron microscope to clarify the causes of edge cracks.Aiming at the problems of grain boundary precipitation behavior,microstructure evolution behavior and the unknown third brittleness temperature range of microalloyed steel,the third brittleness temperature range of microalloyed steel was determined by high temperature thermal simulation test machine.Combined with the current status of CSP thin slab caster production process and equipment,the "low temperature process route" has been adopted to develop the strong controlled cooling process and equipment technology for the secondary cooling high temperature zone at the corner of the continuous casting slab,establishing a new controlled cooling process that stably realizes the multi-phase change grain ultra-fineness and structural transformation of the slab corner structure.Combined with the actual production of the CSP thin slab caster,the influence factors of the edge crack defect in the protection casting and operation are determined,such as the tundish structure,the ladle shroud argon blowing structure,the mould powder,and the slag removal operation.Corresponding improvement measures are proposed.Through the improvement and implementation of the above technologies,the quality of the microalloyed steel products produced by the CSP thin slab continuous casting and rolling process has been significantly improved.