Numerical Simulation Of Temperature And Stress In Secondary Cooling Zone Of Beam Blank Continuous Casting

One of the most remarkable achievements in the history of continuous casting development is the near net shape continuous casting technology,which is also an important development trend of the current steel industry.The beam blank is one of the near net shape continuous casting technologies.Its main purpose is to roll H-beam.However,China's research on beam blank is still in its infancy,and the quality and quantity of beam blank produced are far from domestic demand.Therefore,it is very necessary to carry out in-depth research on beam blank.In the paper,the beam blank of "555 mm × 440 mm × 90 mm" in a steel mill in China is taken as the research object.From the idea of improving the quality of the slab by improving the secondary cooling water distribution,the continuous casting process parameters and cooling system on site conduct a comprehensive survey to identify key factors that affect the quality of the slab.Then,based on the numerical simulation software ANSYS,established the two-dimensional and three-dimensional mathematical models.The coupling field of temperature and stress during solidification heat transfer from mold to secondary cooling zone and its effect on slab quality were studied and analyzed.Among them,the paper proposes a new three-dimensional moving boundary numerical simulation method based on ANSYS.The main conclusions of this paper are as follows:(1)According to the site investigation,the secondary cooling water distribution system of the beam blank is unreasonable,and the surface temperature of the slab is between 700°C and 900 °C during straightening.It is in the temperature brittle zone of steel and is prone to surface cracks.(2)The numerical simulation results show that the section of the beam blank is complex,and its heat transfer and solidification characteristics are different from those of conventional casting slab.In the early stage of continuous casting,the change in the high temperature zone is in a state of being approximately proportionally reduced in proportion,and in the later stage,a triangular high temperature zone centered on the center of the liquid is formed.Among them,the heat transfer rate of the flange tip is the fastest,the flange is the second,and the fillet is the slowest.The temperature curve is fluctuating,and the main reason for the temperature recovery is the release of latent heat of solidification and the decrease of water volume in each region.(3)The effects of casting speed,superheat and water content on slab temperature and stress were studied.It was found that the changes of casting speed and water content had greater influence on slab surface temperature and stress than superheat.When the casting speed is increased by 10%,the shell thickness will be reduced by 3%~6%;when the superheat is increased by 10 ?,the maximum heat flux density will be increased by 4% ~ 7%,and the shell thickness will be reduced by 2%~4%.(4)The slab section temperature curve shows that with the increase of the distance from the meniscus,the section temperature curve will become smoother and the temperature distribution will be more and more balanced.At 3.9 m from the meniscus,the center of the web solidifies completely with a thickness of 45 mm;and at 10.8 m from the meniscus,the whole slab solidifies completely with a thickness of 80 mm at the center of the narrow surface.(5)Compared with the thermal stress and bending stress,it is found that the thermal stress is mainly affected by the temperature gradient.The greater the temperature gradient,the greater the thermal stress.The high stress zone mainly concentrates on the flange tip slightly and the flange.Under the influence of bending stress,the high stress zone is mainly located on the inner wall of the flange between the fillet and the inner angle of the flange.