| In order to realize the hot delivery and hot charging technology can play its economic role in actual production, it must implement and use of defect free slab, in order to adapt to the hot delivery and hot charging, must produce defect free slab. The development of non key technical defects casting billet, to study the protective slag,continuous casting crystallizer, two cold, level fluctuation on the production of wide and thick slab quality influence, as well as the different techniques are analyzed, the production defect free slab method. The steel 4# thick slab continuous casting machine in the steel production type based on that, the internal quality of the slab is very suitable for hot charging process, but for the surface quality, due to the hot charging and direct rolling process, in the process of rapid compensatory heating reduces the removal of slab surface oxide skin, realistic conditions but not for surface finishing, which means difficult to check and clean the surface defects of shallow,with surface defects is equal with the hidden danger, these surface defects will be finished rolled surface defects in rolling. In view of the above problems, the main factors influencing the 4# of casting billet production without cleaning rate, according to different affecting factors, put forward the improvement measures from the steel composition, the accuracy of the equipment, the slab surface temperature control model, operating system etc.. In order to resolve the vertical slab crack, developed in the use of the big chamfer angle mould of slab quality defects formation mechanism of systematic research and analysis, research and development of the control model of plate special two cold surface temperature, surface temperature calculation of two cooling water guide, the billet surface temperature control in a more reasonable scope in in guarantee, billet temperature plasticity at the same time, but also to meet the billet internal cooling requirements, so that we can prevent the emergence of intermediate crack. In order to solve the problem of slab narrow side argon bubble problem, research and development of the semi permeable stopper and longevity. The side hole groove immersion nozzle, designed and built the hydraulic model of the crystallizer is based on the similarity principle, analysis is combined with the mathematical simulation method of the flow in the mold, the way we can study why the formation of initial solidified shell surface of argon bubbles. By coupling finite element model of thermal stress, thermal state of the mold copper plate, different temperature, mold temperature in different places the same casting and cooling condition comparison between mold and billets heat flux distribution and the air gapand the temperature field of billet and slab cooling down the solidification process. The billet defects actually occurs, the corresponding design, to achieve a wide and thick slab without cleaning. After the implementation of the scheme, results show that: because of the slab causes the steel belt production is greatly reduced by the application of 2.25%, reduced to the 0.45%, the quality of the products is greatly improved, the application effect is good. Casting cleaning rate is greatly reduced,cleaning rate reduced from 50% to below 25%, the full realization of 200, 250 mm section and arc not cutting angle, non Nb containing steel fully reach the hot delivery and hot charging process, casting qualified rate increased from 96.59% to more than99.59%, billet quality has been improved significantly, greatly reduces the casting cleaning rate, improve the casting billet hot delivery ratio, resulting in significant economic and social benefits. |
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