CN-116511439-B - Experimental device and method for preparing initial solidification shell of crystallizer permanent magnet stirring square billet

CN116511439BCN 116511439 BCN116511439 BCN 116511439BCN-116511439-B

Abstract

The application discloses an experimental device and method for preparing initial solidification blank shells of a crystallizer permanent magnet stirring square blank, wherein the device comprises a control system, a crucible, a heating furnace for heating the crucible, a permanent magnet stirring module for realizing permanent magnet stirring of molten steel in the crucible, a crystallizer and a blank pulling module matched with the crystallizer, wherein the crystallizer is matched with a crystallizer copper mold, and the control system is respectively and electrically connected with the heating furnace, the permanent magnet stirring module and the blank pulling module. The device and the method can simulate the preparation of the initial solidification shell of the square billet of the crystallizer under different permanent magnet stirring conditions, have the advantages of simple structure, simple and convenient maintenance, low cost and diversified magnetic field modes, improve the controllability of the quality of the casting blank and improve the quality of the casting blank. The method can be used for researching the influence of permanent magnet stirring of the crystallizer on the initial solidification shell of the square billet, is used for researching the optimal permanent magnet stirring conditions of the crystallizer for different steel grades, and provides guidance for industrial application of the permanent magnet stirring of the crystallizer.

Inventors

ZENG JIE
PENG JIANFEI
WANG WANLIN
ZHU CHENYANG
YANG RENYI
YUAN SHUAIJIE

Assignees

中南大学

Dates

Publication Date: 20260505
Application Date: 20230329

Claims (5)

1. The experimental method for preparing the initial solidification blank shell of the square billet is characterized in that the adopted device comprises a control system, a crucible for containing molten steel, a heating furnace for heating the crucible, a permanent magnet stirring module for realizing permanent magnet stirring of the molten steel in the crucible, a crystallizer and a blank pulling module matched with the crystallizer, wherein the crystallizer is matched with a copper mold of the crystallizer, the control system is respectively electrically connected with the heating furnace, the permanent magnet stirring module and the blank pulling module, the permanent magnet stirring module comprises a pair of permanent magnets, a permanent magnet rotating motor and an upper telescopic device and a lower telescopic device, the permanent magnets are driven to rotate by the permanent magnet rotating motor, the permanent magnets are arranged on the upper telescopic device and the lower telescopic device, the experimental method further comprises a copper mold vibrating motor for driving the copper mold of the crystallizer to vibrate, and the copper mold vibrating motor of the crystallizer is electrically connected with the control system, and the experimental method comprises the following steps: 1) Placing 20-25kg of required experimental steel in a crucible, placing the crucible in a heating furnace, and adjusting the height of a permanent magnet module according to the experimental steel types and experimental requirements to realize the control of the magnetic field intensity at the crucible; 2) The method comprises the steps of starting a heating furnace to melt experimental steel, keeping the temperature above 30-70 ℃ of liquidus temperature of the steel grade, starting permanent magnet stirring, adjusting stirring speed to ensure that the components and the temperature of molten steel are uniform, then adding crystallizer protection slag matched with the steel grade into the molten steel, forming a crystallizer protection slag layer after the crystallizer protection slag layer is completely melted, and measuring the temperature of the crystallizer protection slag layer; 3) Slowly inserting a crystallizer copper mold into a molten pool, starting a crystallizer copper mold vibration motor, driving the crystallizer copper mold to vibrate according to a set vibration frequency and a set vibration amplitude, rapidly cooling a crystallizer protection slag layer on the crystallizer copper mold to form a protection slag film, and rapidly solidifying molten steel on the crystallizer copper mold wrapped with the protection slag film along with the continuous insertion of the crystallizer copper mold; 4) When the crystallizer copper mold descends to a set position, stopping downward movement of the crystallizer copper mold, staying for 1-10 seconds, enabling the thickness of an initial solidified blank shell formed by solidifying molten steel on the surface of the crystallizer to reach 1-6mm, starting a blank pulling module to drive the solidified blank shell to move downward, enabling new molten steel to contact with the crystallizer copper mold, and pulling out the initial solidified blank shell with a certain length, wherein a permanent magnet stirring module is kept to operate all the time; 5) The crystallizer copper mold drives the initial solidification blank shell to move upwards to separate from a molten pool in the crucible, the initial solidification blank shell of the crystallizer permanent magnet stirring square blank is obtained after cutting, and finally the crystallizer permanent magnet stirring module is closed.
2. The experimental method of claim 1, wherein the heating furnace is provided with a heating element and a thermocouple.
3. The method according to claim 2, wherein the crucible comprises an outer pot body and an inner pot body which are assembled in a sleeved mode, and the thermocouple is arranged between the outer pot body and the inner pot body.
4. The experimental method according to claim 3, wherein the amplitude of the copper mold of the crystallizer is 1-6mm and the vibration frequency is 50-350 times/min.
5. The method according to claim 4, wherein the initial solidified shell has a length of 300-800mm.

Description

Experimental device and method for preparing initial solidification shell of crystallizer permanent magnet stirring square billet Technical Field The invention belongs to the technical field of blank shell preparation, and particularly relates to an experimental device and method for preparing a crystallizer permanent magnet stirring square blank initial solidification blank shell. Background The surface and internal defects of the casting blank are closely related to the flowing state of molten steel in the crystallizer, and researches show that nearly 80% of the surface defects of the casting blank originate from the crystallizer. Therefore, controlling and improving the flow of molten steel in a crystallizer is important to improve the quality of casting billets, particularly the surface quality. The electromagnetic stirring of the crystallizer can strengthen the flow of molten steel during pouring and solidification initiation, strengthen the heat transfer of the molten steel in the crystallizer, reduce the superheat degree of the molten steel, further realize the control of the surface (blank shell) quality of a solidified blank, and get the wide attention of metallurgical workers. However, electromagnetic stirring requires high-power variable-frequency current to generate an alternating magnetic field, equipment is complex, energy consumption is high, maintenance cost is high, meanwhile, flowing water is required to be used for cooling in order to prevent the coils from overheating, on one hand, cooling water takes away joule heat of the coils and wastes electric energy, and on the other hand, the coils are still short in service life and need to be replaced frequently even though high-quality cooling water is used. With the continuous improvement of the performance of magnetic materials, permanent magnetic stirring has become an effective alternative method for electromagnetic stirring. Research shows that the electric energy consumption of permanent magnetic stirring is only one tenth of that of electromagnetic stirring. Therefore, the development of the permanent magnet stirring technology has important significance for reducing the energy consumption and saving the production and operation cost for enterprises. The test result of the permanent magnetic stirring at the solidification tail end of the small square billet high-carbon cord steel shows that the permanent magnetic stirring at the solidification tail end can reduce carbon segregation in the small square billet, and the energy-saving effect is remarkable. Patent CN108580803a discloses a permanent magnet stirrer at the solidification end of a casting blank of a steelmaking continuous casting machine, and the purpose of stirring a steel blank liquid core is achieved by driving a permanent magnet to rotate through a hydraulic motor. However, the application of the crystallizer permanent magnet stirring technology is rarely reported. The utility model patent CN212419548U discloses a casting blank crystallizer of a steelmaking continuous casting machine, wherein a permanent magnet stirrer is arranged outside the crystallizer, and a hydraulic motor is adopted to drive a permanent magnet to rotate so as to realize stirring. The motion mode of the magnetic field of the patent is single, and the requirements of actual production problems can not be solved by simply replacing permanent magnetic stirring and electromagnetic stirring. In order to study the influence of permanent magnet stirring of a crystallizer on an initial solidification blank shell, the most ideal method is an industrial field experiment or a small pilot-scale continuous casting machine experiment, but the method faces a plurality of problems of high experimental risk, high raw material consumption, high energy consumption, influence on a normal production flow, overhigh experimental cost and the like. In addition, some researchers simulate the role of permanent magnet stirring in initial solidification of a crystallizer by establishing a mathematical model, but the methods are based on certain assumptions, and all the factors need comprehensive and accurate boundary conditions and physical parameters, which affect the correctness of simulation results, and the simulation results often have difficulty in comprehensively and accurately explaining the formation problem of initial solidification shells containing complex, multiphase and instantaneous three-way-one-way-reverse phenomena in the crystallizer. In order to practically study the influence of permanent magnet stirring of a crystallizer on initial solidification of molten steel and realize industrial landing application of the permanent magnet stirring of the crystallizer, a new thought and a new method are needed. Disclosure of Invention In view of the above, the invention aims to provide an experimental device and a method for preparing a square billet initial solidification shell of a crystallizer by permanent magnet stir