Design Of New-style Continuous Bending And Straightening Curve And Analysis In The Cast Slab

The bending and straightening technology of continuous casting slab is one of the key technologies to develop efficient continuous casting.Besides,good bending and straightening technology plays an important role in improving the production rate of continuous casting machine and improving the quality of slab.In this paper,a new type of continuous bending and straightening curve is designed and developed based on the creep characteristics of steel Q345 C for bending and straightening technology of slab continuous casting.Simulation analysis of thermo-solid coupling during solidification and heat transfer process and thermodynamic coupling simulation analysis of bending straightening process are carried our in this paper.During the bending and straightening process,reducing the strain rate of the continuous casting slab can reduce the occurrence of cracks in the slab and improve the quality of the slab.The slab is always at high temperature and the creep characteristic is obvious.The development and design of the new continuous bending straightening curve is based on the above two points.The Gleeble3800 thermal simulation test was used to carry out the thermoplastic experiment and the high temperature creep experiment on the steel Q345 C sample.According to the creep law,the expression of steady-state creep rate is obtained by nonlinear fitting of the experimental data.Compared with the original R9300 curve,the new curve has a smooth connection,which has the characteristics of continuous curvature change and small curvature change rate.The design of the curve fully considered the influence of the high temperature creep characteristic of the slab.In addition,the new curve eliminates the basic arc segment and increases the effective bending or straightening arc length,while reducing the height of the caster,effectively reducing the static pressure of molten steel on the adverse effects of continuous casting billet.According to the curve characteristics of the new continuous bending and straightening curve and the roller arrangement principle,the roll of the new curve is rearranged and the roll coordinates of each roller are determined.The temperature field of the solidification and heat transfer process of the continuous casting slab is simplified by the finite element software Marc as a two-dimensional unsteady heat transfermodel for simulation analysis.The temperature field and the shell thickness of the slab are analyzed emphatically,and the temperature change and the shell thickness change of the key nodes are explained in detail.Through the thermo-mechanical simulation of the bending and straightening process of continuous casting billet,the equivalent creep strain and the equivalent strain rate of the inner and outer arcs of the new continuous bending and straightening curve and the original R9300 curve are compared and analyzed.It is found that the new continuous bending and straightening curve can fullly play and use the high temperature creep characteristics of the billet,the role of creep characteristics in the process of bending and straightening is obvious,so the use of new continuous bending and straightening curve has obvious superiority.