Study On Stress In Second Cooling Zone Of Thin Slab Continuous Casting And Development Of Simulation Software

The thin slab continuous casting and rolling has brought great benefit to the world for its better quality, lower cost, higher casting speed. During thin slab continuous casting, the solidification solidified shell will generate more crack than normal slab for higher casting speed, thinner solidified shell and stronger cooling. So the quantitative analysis in the influence of second cooling system and caster equipment to the quality of thin slab is greatly significant to the development of thin slab continuous casting technology and the design of thin slab continuous caster.In this paper, author establishes a thermal elasto-plastic stress model for thin slab. The equations between stress and strain are given on high temperature and plane strain conditions for elastic and plastic area of thin slab section. To assure precision of the model, transitional area is brought into thin slab section and the equations between stress and strain are described by weighted average elastic-plastic matrix. During the solving process of the finite element method, triangle element is adopted for its better convergence quality, all of the units and points in the thin slab section are automatic numbering, the stiffness matrix of whole body is stored in to one dimension array with method of changing belt-width, which causes the calculating speed is fast and the occupied memory capacity is small. The temperature field is looked as initial load and the method of changing stiffness matrix is adopted during the calculation of stress and strain. The liner equation is solved with the method of [L]T[L0][L].The stress simulation soft in second cooling zone of thin slab continuous casting, having the features of strong function, fast calculation speed, friendly windows and easily accepted, is developed with the computer language of Visual Basic 6.0, the soft in this paper. To expand the use range of the soft, author selects equivalent cuboid mold to calculate heat transfer of thin slab instead of different kinds of thin slab caster mold. The input program of temperature field is developed, when the thin slab moves out of mold, in order to input data from practical measure or more accurate simulation of heat transfer in mold. Different kinds of thin slab caster, such as the types of arc, straight-arc and vertical bending, could be simulated heat transfer, stress and strain of their production in this soft, linking to access, which could stores process parameters and structure parameters of continuous caster, thermal physical property parameters and thermal mechanical property parameters of steel for being called anytime. The thin slab section moves along the strand, and the data of temperature, stress, strain and crack formation index is showed when the soft is running. The soft, including Surfer8.0 has strong date processing function, the simulated result data of any sections is made into contour map.16Mn steel, produced by MDH thin slab caster, is simulated with the soft developed and MSC.Marc, the result data of equivalent stress and crack formation index is got from them during the initial , middle and final stage, and is well consistent after comparing. The accuracy of model and algorithm is testified. The bulging of thin slab between two rolls along the strand is simulated with elasto-plastic creep model of MSC.Marc, on different casting speed and distance between two rolls condition. The result data is compared to slab bulging calculated formula, and is well consistent, too.