This paper summarizes experimental approaches and simulation results in order to establish a general proposition regarding SEN wear mechanisms.Marangoni convection is considered to be a major contribution to continuou...This paper summarizes experimental approaches and simulation results in order to establish a general proposition regarding SEN wear mechanisms.Marangoni convection is considered to be a major contribution to continuous SEN wear,usually causing characteristic corrosion grooves.It is governed by the interface tension gradient in the vicinity of the three phase boundary slag/refractory/steel.This interface tension gradient is caused by a lower activity of the oxygen dissolved in the steel close to the refractory/steel interface.This is due to the reducing action of the solid carbon,which is a component of the refractory.By a simulation model using the Effective Equilibrium Reaction Zone technique a calculation of the interface tension differenceΔσwas performed.While for an LC steel and the related slag a valueΔσ=150mN/m was received,this quantity is negligible in the case of a TRIP steel.Accordingly,also the wear is much less for the TRIP steel.Marangoni convection is decisive for the mass transfer at the refractory/slag interface.Here dissolution of zirconia,but also oxidation of carbon takes place.For the latter one,the above mentioned simulation showed that reduction of silica in the mold slag takes place at the three phase boundary slag/refractory/steel by solid carbon,as the activity of silicon is reduced by dissolution in the liquid steel.This is the main source of oxygen for carbon oxidation at the three phase boundary.Therefore the three phase boundary is the focus of SEN wear：It unites intense bath movement due to Marangoni convection,oxidation of carbon by SiO_2reduction and zirconia erosion and dissolution into the melt.Within the refractory itself,a thin layer of several millimetres shows reactions with slag components.This causes especially destabilisation of stabilised zirconia and prepares later erosive wear.Steel does not penetrate into the SEN microstructure,carbon dissolution is only possible at the steel/refractory interface.The results quoted here enable justified expectations about the SEN wear in dependence on the steel/slag grade.Further simulation offers the possibility to quantify the effect of parameter variations on SEN wear.展开更多
SEN is a key relative technology to TSCC, the quality of which influences not only the heats of continuous casting but also the stream field in the mould. The powder line is the key part of SEN, that determines the co...SEN is a key relative technology to TSCC, the quality of which influences not only the heats of continuous casting but also the stream field in the mould. The powder line is the key part of SEN, that determines the continuous casting life. In this study the microstructure of used SEN samples were examined by SEM, the causes of the abnormal erosion phenomena were analyzed from slag corrosion mechanism, reactions between carbon containing refractories and slag and molten steel, properties of refractories. The improvement of the quality of SEN were achieved by adjusting the graphite content and composite structure designing of SEN＇s powder line.展开更多
基金the funding support of K1-MET GmbH,metallurgical competence centerthe competence center K1-MET is supported by COMET (Competence Center for Excellent Technologies) ,the Austrian program for competence centers
文摘This paper summarizes experimental approaches and simulation results in order to establish a general proposition regarding SEN wear mechanisms.Marangoni convection is considered to be a major contribution to continuous SEN wear,usually causing characteristic corrosion grooves.It is governed by the interface tension gradient in the vicinity of the three phase boundary slag/refractory/steel.This interface tension gradient is caused by a lower activity of the oxygen dissolved in the steel close to the refractory/steel interface.This is due to the reducing action of the solid carbon,which is a component of the refractory.By a simulation model using the Effective Equilibrium Reaction Zone technique a calculation of the interface tension differenceΔσwas performed.While for an LC steel and the related slag a valueΔσ=150mN/m was received,this quantity is negligible in the case of a TRIP steel.Accordingly,also the wear is much less for the TRIP steel.Marangoni convection is decisive for the mass transfer at the refractory/slag interface.Here dissolution of zirconia,but also oxidation of carbon takes place.For the latter one,the above mentioned simulation showed that reduction of silica in the mold slag takes place at the three phase boundary slag/refractory/steel by solid carbon,as the activity of silicon is reduced by dissolution in the liquid steel.This is the main source of oxygen for carbon oxidation at the three phase boundary.Therefore the three phase boundary is the focus of SEN wear：It unites intense bath movement due to Marangoni convection,oxidation of carbon by SiO_2reduction and zirconia erosion and dissolution into the melt.Within the refractory itself,a thin layer of several millimetres shows reactions with slag components.This causes especially destabilisation of stabilised zirconia and prepares later erosive wear.Steel does not penetrate into the SEN microstructure,carbon dissolution is only possible at the steel/refractory interface.The results quoted here enable justified expectations about the SEN wear in dependence on the steel/slag grade.Further simulation offers the possibility to quantify the effect of parameter variations on SEN wear.
文摘SEN is a key relative technology to TSCC, the quality of which influences not only the heats of continuous casting but also the stream field in the mould. The powder line is the key part of SEN, that determines the continuous casting life. In this study the microstructure of used SEN samples were examined by SEM, the causes of the abnormal erosion phenomena were analyzed from slag corrosion mechanism, reactions between carbon containing refractories and slag and molten steel, properties of refractories. The improvement of the quality of SEN were achieved by adjusting the graphite content and composite structure designing of SEN＇s powder line.
