Study On Bulging Deformation Of Slab In Continuous Straightening Process

Straightening with liquid core is one of the key technologies to realize high efficiency continuous casting. The total deformation of the solidified shell includes not only straightening deformation under the action of straightening moment, but also bulging deformation under the action of static pressure of molten steel and deformation caused by other factors. Once the bulging deformation exceeds the critical value of slab deformation, the internal crack will appear. Therefore, it has important theoretical and practical significance to study the bulging deformation of solidified shell in the area of straightening.Based on the high temperature creep and elastic theory of strand materials, a viscoelastic mathematical model for solving the bulging deformation of continuous casting slabs was established. The boundary conditions of the model were determined according to the initial state of solidified shell, and the bulging deformation and bulging strain were calculated by using this model.A three-dimensional non-steady state heat transfer finite element model was established, and the thermal physical parameters of the strand materials were selected reasonably. The temperature distribution and the thickness of solidified shell were obtained.Consider the effect of the creep properties of the strand materials at high temperature and the movement of the casting slab on the bulging deformation, a dynamic thermo-mechanical coupling finite element model was established for the straightening process, and the parameters of the high temperature mechanical characteristics of strand materials were selected reasonably. The variation of the bulging deformation, the strain and the strain rate at the solid-liquid interface of the casting slab were obtained. And the effect of the roll pitch and casting speed on the bulging deformation, the strain and the strain rate at the solid-liquid interface of the casting slabs were calculated and analyzed.