Bulging Strain Analysis Of Continuous Casting Slab During Solidification

In the process of continuous casting slab production,bulge deformation will occur due to the action of steel hydrostatic pressure,and abnormal bulge will cause slab quality defects and steel leakage and other casting accidents.Effectively controlling the influence of steel static pressure on the slab floor,so as to reduce the liquid level fluctuation of mold,control the normal distribution of bulge deformation and bulge strain at the two-phase boundary,is very important for ensuring the internal and external quality of slab and developing and designing a high-level slab continuous casting machine.In this paper,aiming at the engineering practice and taking the straight arc slab continuous casting machine in a steel plant as the object,a thermodynamic coupling model of the bulging bulging of continuous casting slab with four pairs of rollers constraint was established.The contact arc length of the support roll in casting flow was introduced,and the influence of the surface contact between the support roll and slab on the bulging bulging deformation was considered.The bulging bulging deformation of slab continuous casting during the solidification process under high temperature creep characteristics was studied.The research results have important theoretical significance and engineering application value.The main work contents of this paper include:(1)Establish a slab solidification heat transfer model to analyze the influence of different parameters on the degree of slab solidification.First,establish a two-dimensional heat transfer model to simulate the temperature field,study the rule of slab shell thickness during the solidification process,obtain the curve of slab shell thickness,and the temperature field of slab cross-section at any time and experimentally verify the temperature field.It is found that in the non-steady-state casting state,the casting temperature and casting speed have a significant impact on the slab surface temperature,slab shell thickness,and even the solidification endpoint.In particular,when the casting speed is changing,the farther the position from meniscus of the crystallizer,the smaller effect on the slab surface temperature.(2)Establish a four-roll constrained continuous casting slab bulging thermomechanical coupling model.By establishing a three-dimensional bulging thermomechanical coupling finite element model,the temperature field results obtained from the slab solidification heat transfer are added as boundary conditions to the bulging model,and the material high-temperature creep characteristics are fully considered to study the bulging deformation.In order to better simulate the actual situation,the slab between the four pairs of rollers is modeled,and the bulging deformation of the slab between the middle two rollers is analyzed to obtain the bulging deformation rule of the slab.(3)Study the influence of the contact arc length between the roll and the slab on the bulging strain.Considering the influence of the contact arc length between the roll and the slab on the two-phase interface bulging strain of the continuous casting slab,the relationship between the contact arc length between the roll and the slab and the bulging strain is derived,and the analytical solution of the contact arc length between the roll and the slab on the bulging strain is obtained.By deriving the relationship between the contact arc length between the roll and the slab and the bulging strain,the influence rule of the contact arc length between the roll and the slab on the bulging strain is obtained.(4)Analyze the influence rules of roll diameter,space between rolls,and casting speed on slab shell bulging deformation and bulging strain at the solid-liquid interface of the slab.When the roll diameter increases by 50 mm,the bulging strain at the same position will decrease by about 0.005%,so increasing the roll diameter can effectively increase the roll contact arc length and reduce the bulging strain.As the roll spacing increases from 260 mm to 300 mm in turn,the compressive strain at the center of the slab will increase by 0.05% in turn.As the casting speed increases from 0.8 m/min to 1m/min,the compressive strain at the center of the slab will increase by 0.0045% in turn.In conclusion,when the casting speed fluctuation is not significant,the influence on the bulging strain is relatively small.When the roll diameter increases,the bulging strain at the two-phase interface of the slab will also increase accordingly.The change in space between rolls is the main factor affecting the bulging strain.