Control And Optimization Of Continuous Casting Process Of Wide Width Stainless Steel

Shanxi Taigang Stainless Steel CO.,LTD.get the high cleanliness stainless steel through optimization of smelting process,which has a good control on the total oxygen content and inclusions quantity in molten steel.But the wide slab casting has the questions such as lots of surface defects,high unqualified rate of rolling.In order to solve the problem,the study on the physical chemistry properties of mold fluxes and Preferred experiment on variety of them,and optimization of parameters of submersed nozzle for continuous casting by using of submerged nozzle,combined with the production experiment,obtained the reasonable parameters,by evaluating Parameter of impact depth,slag level fluctuation,slag thickness and entrapment.Optimized nozzles are used in the production and the conclusions are following:(1)No.1,2 mould fluxes is suiting for Casting from Solidification characteristics of 304 Series and 316 L wide CC.The surface of slag is stable,and mould fluxes has a good condition,and sintering phenomenon is non-obvious,and narrow surface slag is active in crystallizer.And the slab surface quality requirements of austenitic stainless steel have been met for the production.Other types of slags have a high fluctuation level in process,and the slab surface have a serious of scab,sunken and metal particle defect.(2)Water model is apply for physical simulation,and combed with field test.The experimental results show that trapezoidal nozzle of what side area is double middle area,Reduce the side of Trapezoid 10 mm is suitable.The quality of casting billet is more improve than before.But the phenomena of sunken,indentation,and slag entrapment is still exist,and nozzle design still cannot meet the requirement of production.And then the flat diameter,rectangular side hole,incline 10°dip angle,the ratio of side area and middle is 1.76,and flat thick bottom nozzle has been designed and developed.It results that little rush of the flow of molten steel,stable surface and the thickness difference between liquid and slag is reduced to 7-11 mm.Uniform spreading is realization basically.The best shape of nozzle has been tested in the field,the result show that the surface quality of slab is improved obviously,sunken and slag entrapment defects are disappeared,the number of pressure hole by mould fluxes is reduced obviously,achieving requirement of wide stainless steel slab without regrinding circulation.(3)Optimization for stainless steel smelting process and study on mould fluxes of wide CC and the flow field in the mold,improved the cleanliness level of molten steel.Sunken,indentation,and slag entrapment on the defect surface of wide CC slab from production is reduced significantly,and the surface quality of slab is improved significantly.The wide non-grind slab rate increased to more than 64%,the non-grind level reached the highest level in history,and the unqualified rate of cold rolling is significantly reduced to 4.36%.