Study On Corrosion Of High Manganese And High Aluminium Steel Mold Fluxes To The Submerged Entry Nozzle

In this paper,the conventional high SiO₂ slag and the low reactive slag A-1?A-2 for high manganese and high aluminum steel were used as the research object,the corrosion and dissolution of ZrO₂-C refractory in mould submerged nozzle slag line were studied.The influence of low reactive slag components on refractory erosion was systematically studied,and the dynamic equation of mould slag corrosion on refractory material was established.The mechanism of corrosion dissolution of refractory material by mold slag was put forward.Through the research of this paper the main conclusions are as follows:?1?There are two main characteristics in the inner wall of ZrO₂-C refractory after erosion by mold fluxes.One is that the erosion of slag is the most serious at the three-phase interface between sample and molten slag and gas phase,and the necking phenomenon is the most serious after the erosion of conventional high SiO₂ slag.The wet permeability of slag is large,but the necking phenomenon of low reactive slag is not as obvious as that of conventional high SiO₂ slag after erosion.The second is that the slag adheres to the surface of the sample and forms a layer of slag film after the slag is in contact with the sample.?2?The corrosion of high manganese and high aluminum steel mould fluxes A-1and A-2 on continuous casting submerged nozzle slag line are obviously lower than that of conventional high SiO₂ slag.The size of erosion is as follows:conventional high SiO₂ slag C>low reactive slag A-1>low reactive slag A-2.The results show that the high manganese and high aluminum steel mould fluxes developed by our group have little erosion on submerged nozzle,and will not worsen the service conditions of the nozzle and reduce the service life of the nozzle.Theoretically speaking,the nozzle erosion can meet the requirements of continuous casting technology.?3?The corrosion of conventional high SiO₂ slag or low reactive slag of high manganese high aluminum steel on the slag line of the nozzle is aggravated with the increase of temperature and relative linear velocity.This is mainly due to the increase of temperature and linear velocity,which changes the dynamic conditions of mold slag erosion on refractory,and accelerates the infiltration of mold slag to the nozzle,which results in the increase of nozzle erosion.?4?In the study of the effect of the low reactive slag A-1 and A-2 components for high manganese high aluminum steel mould slag on the corrosion of refractory,it was found that with the increase of slag components Na₂O,CaF₂,Li₂O,B₂O₃,the corrosion of refractory was intensified,which is mainly due to the decrease of viscosity of slag by these low-viscosity components.The surface tension of slag was changed and the erosion was aggravated.The influence factors of erosion were:Na₂O>CaF₂>Li₂O>B2O3.?5?The dissolution rate of erosion increases with the increase of?CaO+BaO?/?Al₂O₃+SiO₂?ratio,because the ratio of?CaO+BaO?/?Al₂O₃+SiO₂?increases the proportion of CaO and BaO network suppressor,and decreases the proportion of SiO₂ and Al₂O₃ network formators,the complexity of the structure of molten slag is reduced,so it can reduce the viscosity of mold fluxes and increase the fluidity of mold fluxes,thus promoting the kinetic condition of corrosion dissolution of mould fluxes to a certain extent.?6?The erosion mechanism of slag on the refractory nozzle can be divided into two processes:the first is the oxidation of carbon,carbon and graphite ZrO₂-C refractories in the sample of ash slag and impurities such as Fe₂O₃,SiO₂ and other components of the oxidation reaction,the blowhole provides the channel for slag penetration;the other is the stabilizer of CaO oxidation stable zirconium exposed exsolution and zirconia particles cracking fragmentation.