A mathematical model was developed to describe the interaction of multiple physical fields in a slag bath during electroslag remelting （ESR） process with a current-conductive mould. The distributions of current dens...A mathematical model was developed to describe the interaction of multiple physical fields in a slag bath during electroslag remelting （ESR） process with a current-conductive mould. The distributions of current density, magnetic induction intensity, electromagnetic force, Joule heating, fluid flow and temperature were simulated. The model was verified by temperature measurements during remelting 12CrMoVG steel with a slag of 50wt%-70wt% CaF2, 20wt%-30wt% CaO, 10wt%-20wt% A1203, and 〈10wt% SiO2 in a 600 mm diameter current-conductive mould. There is a good agreement between the calculated temperature results and the measured data in the slag bath. The calculated results show that the maximum values of current density, electromagnetic force and Joule heating are in the region between the comer electrodes and the conductivity element. The characteristics of current density distribution, magnetic induction intensity, electromagnetic force, Joule heating, velocity patterns and temperature profiles in the slag bath during ESR process with current-conductive mould were analyzed.展开更多
The viscosity of CaF_2-CaO-Al_2O_3-MgO-（TiO_2） slag was measured using a rotating crucible viscometer. Raman spectroscopy analysis was performed to correlate the viscosity to slag structure. The viscosity of the sla...The viscosity of CaF_2-CaO-Al_2O_3-MgO-（TiO_2） slag was measured using a rotating crucible viscometer. Raman spectroscopy analysis was performed to correlate the viscosity to slag structure. The viscosity of the slag was found to decrease with increasing TiO_2 content in the slag from 0 to 9.73wt%. The activation energy decreased from 95.16 kJ /mol to 79.40 kJ /mol with increasing TiO_2 content in the slag. The introduction of TiO_2 into the slag played a destructive role in Al-O-Al structural units and Q^4 units by forming simpler structural units of Q^2 and Ti_2O_6^（4-） chain. The amount of Al-O-Al significantly decreased with increasing TiO_2 content. The relative fraction of Q^4 units in the [AlO_4]^（5-）-tetrahedral units shows a decreasing trend, whereas the relative fraction of Q^2 units and Ti_2O_6^（4-） chain increases with increasing TiO_2 content accordingly. Consequently, the polymerization degree of the slag decreases with increasing TiO_2 content. The variation in slag structure is consistent with the change in measured viscosity.展开更多
Slag is the heart of electroslag remelting(ESR)process.A new mathematical model to design the optimized slag for ESR was developed based on slag–metal equilibrium theory,ion and molecule coexistence theory and modifi...Slag is the heart of electroslag remelting(ESR)process.A new mathematical model to design the optimized slag for ESR was developed based on slag–metal equilibrium theory,ion and molecule coexistence theory and modified Butler’s equation.It was assumed that an overall thermodynamic equilibrium did exist at electrode tip–slag interface.With this model,the equilibrium slag and its surface tension could be obtained quantitatively when the initial compositions of consumable electrode were given.An industrial experiment with four types of slags was carried out in a special steel plant in China.The variation of Al,Si and Mn corresponded well with the deviation of corresponding oxide from equilibrium,reflecting the reasonability of the model.Besides that,the effects of Al in electrode as well as CaO,CaF2 and MgO in slag on the equilibrium slag,dissolved oxygen and surface tension were discussed in detail.展开更多
The structure of electroslag remelting-type CaF_(2)–CaO–Al_(2)O_(3)–CeO_(2)slag with various CaO/Al_(2)O_(3)mass ratios and its correlation with viscosity and surface tension were investigated.The Raman analysis of...The structure of electroslag remelting-type CaF_(2)–CaO–Al_(2)O_(3)–CeO_(2)slag with various CaO/Al_(2)O_(3)mass ratios and its correlation with viscosity and surface tension were investigated.The Raman analysis of the slag shows that with increasing CaO/Al_(2)O_(3)mass ratio from 0.70 to 1.29 in the slag,the polymerization degree of the slag decreased,which was because more complex[AlO_(4)]-tetrahedral units of Q_(Al)^(3) and Q_(Al)^(4)were depolymerized to form relatively simpler structural units Q_(Al)^(0),Q_(Al)^(1),and Q_(Al)^(2),and the excess oxygen ions introduced by CaO promoted the transformation of[AlO_(4)]-tetrahedral units to[AlO_(6)]-octahedral units.Increasing CaO/Al_(2)O_(3)mass ratio has an obvious effect on reducing the viscosity and activation energy for viscous flow of the slag,resulting from the depolymerization of the slag.Owing to the decrease in the polymerization degree and the increase in the total Ca^(2+)content of the slag,the surface tension of the slag increases with the increase in CaO/Al_(2)O_(3)mass ratio.The surface tension of the slag changes slightly with the temperature,irrespective of CaO/Al_(2)O_(3)mass ratio from 0.70 to 1.29 in the slag.展开更多
The composition of a slag system has been shown to be particularly important and influential for the new technology of electroslag remelting withdrawal process.The oxidation of the GH984G alloy elements,in contact wit...The composition of a slag system has been shown to be particularly important and influential for the new technology of electroslag remelting withdrawal process.The oxidation of the GH984G alloy elements,in contact with different contents of CaF_(2)–CaO–Al_(2)O_(3)–MgO–TiO_(2)–SiO_(2)in various slag systems,has been investigated in the present study by performing slag–metal equilibrium experiments and ion and molecule coexistence theory analysis.The results show that CaF_(2)and MgO have only a minor effect on the oxidation rates of Al and Ti in the GH984G superalloys.However,it was found that SiO_(2)would intensify the oxidation degree of Al and Ti,and Al was found to become easier oxidized than Ti.Moreover,CaO was found to reduce the activity of SiO_(2)and,thereby,also the oxidation degree of Al and Ti.Also,TiO_(2)was found to reduce the oxidation rate of Ti and instead increase the oxidation rate of Al.Finally,the effect of Al_(2)O_(3)on the oxidation of Al and Ti was observed to be opposite to that of TiO_(2).The calculated results were found to be in good agreement with experimental measurements.Moreover,viscosity experiments showed that CaO would rapidly increase the viscosity of the slag at low temperatures,and that the viscosity of the slag would increase with an increase in SiO_(2)content.展开更多
A numerical model coupled with a multi-physical field based on dynamic formation of slag skin is established.After validation by comparing the experimental and simulation results of depth of metal pool,slag skin thick...A numerical model coupled with a multi-physical field based on dynamic formation of slag skin is established.After validation by comparing the experimental and simulation results of depth of metal pool,slag skin thickness and melt rate,it is utilized to investigate the effect of melt current on the coupled multi-physical field,slag skin thickness,metal pool depth and the heat flow distribution during electroslag remelting(ESR)Inconel 625 solidification process.The results showed that with the increase in the melt current,the velocities of ESR system and the temperature of metal pool increased,whereas the highest temperature of slag bath firstly decreased and then increased.With the increase in the melt current,the slag skin thickness,metal pool depth and melt rate increased.Furthermore,the characteristics of the heat flow distribution and the effect of melt current on the heat flow distribution were analysed.展开更多
基金supported by China Postdoctoral Science Foundation (No.20100471452)
文摘A mathematical model was developed to describe the interaction of multiple physical fields in a slag bath during electroslag remelting （ESR） process with a current-conductive mould. The distributions of current density, magnetic induction intensity, electromagnetic force, Joule heating, fluid flow and temperature were simulated. The model was verified by temperature measurements during remelting 12CrMoVG steel with a slag of 50wt%-70wt% CaF2, 20wt%-30wt% CaO, 10wt%-20wt% A1203, and 〈10wt% SiO2 in a 600 mm diameter current-conductive mould. There is a good agreement between the calculated temperature results and the measured data in the slag bath. The calculated results show that the maximum values of current density, electromagnetic force and Joule heating are in the region between the comer electrodes and the conductivity element. The characteristics of current density distribution, magnetic induction intensity, electromagnetic force, Joule heating, velocity patterns and temperature profiles in the slag bath during ESR process with current-conductive mould were analyzed.
基金financially supported by the Fundamental Research Funds for the Central Universities (Grant No. FRF-TP-15-010A2)China Postdoctoral Science Foundation (Grant No. 2016T90035)
文摘The viscosity of CaF_2-CaO-Al_2O_3-MgO-（TiO_2） slag was measured using a rotating crucible viscometer. Raman spectroscopy analysis was performed to correlate the viscosity to slag structure. The viscosity of the slag was found to decrease with increasing TiO_2 content in the slag from 0 to 9.73wt%. The activation energy decreased from 95.16 kJ /mol to 79.40 kJ /mol with increasing TiO_2 content in the slag. The introduction of TiO_2 into the slag played a destructive role in Al-O-Al structural units and Q^4 units by forming simpler structural units of Q^2 and Ti_2O_6^（4-） chain. The amount of Al-O-Al significantly decreased with increasing TiO_2 content. The relative fraction of Q^4 units in the [AlO_4]^（5-）-tetrahedral units shows a decreasing trend, whereas the relative fraction of Q^2 units and Ti_2O_6^（4-） chain increases with increasing TiO_2 content accordingly. Consequently, the polymerization degree of the slag decreases with increasing TiO_2 content. The variation in slag structure is consistent with the change in measured viscosity.
基金The authors wish to express their gratitude to Xining Special Steel Plant,Chinathe National Natural Science Foundation of China(Grant Nos.51874034 and 51674024)for their financial support.
文摘Slag is the heart of electroslag remelting(ESR)process.A new mathematical model to design the optimized slag for ESR was developed based on slag–metal equilibrium theory,ion and molecule coexistence theory and modified Butler’s equation.It was assumed that an overall thermodynamic equilibrium did exist at electrode tip–slag interface.With this model,the equilibrium slag and its surface tension could be obtained quantitatively when the initial compositions of consumable electrode were given.An industrial experiment with four types of slags was carried out in a special steel plant in China.The variation of Al,Si and Mn corresponded well with the deviation of corresponding oxide from equilibrium,reflecting the reasonability of the model.Besides that,the effects of Al in electrode as well as CaO,CaF2 and MgO in slag on the equilibrium slag,dissolved oxygen and surface tension were discussed in detail.
基金the National Natural Science Foundation of China(Grant No.52104339)the Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking(Grant No.KF-20-3)is greatly acknowledged.
文摘The structure of electroslag remelting-type CaF_(2)–CaO–Al_(2)O_(3)–CeO_(2)slag with various CaO/Al_(2)O_(3)mass ratios and its correlation with viscosity and surface tension were investigated.The Raman analysis of the slag shows that with increasing CaO/Al_(2)O_(3)mass ratio from 0.70 to 1.29 in the slag,the polymerization degree of the slag decreased,which was because more complex[AlO_(4)]-tetrahedral units of Q_(Al)^(3) and Q_(Al)^(4)were depolymerized to form relatively simpler structural units Q_(Al)^(0),Q_(Al)^(1),and Q_(Al)^(2),and the excess oxygen ions introduced by CaO promoted the transformation of[AlO_(4)]-tetrahedral units to[AlO_(6)]-octahedral units.Increasing CaO/Al_(2)O_(3)mass ratio has an obvious effect on reducing the viscosity and activation energy for viscous flow of the slag,resulting from the depolymerization of the slag.Owing to the decrease in the polymerization degree and the increase in the total Ca^(2+)content of the slag,the surface tension of the slag increases with the increase in CaO/Al_(2)O_(3)mass ratio.The surface tension of the slag changes slightly with the temperature,irrespective of CaO/Al_(2)O_(3)mass ratio from 0.70 to 1.29 in the slag.
基金supported by the National Key Research and Development Program(2017YFB0305201)the National Natural Science Foundation of China(Grant Nos.51674070,51874085)"Innovation&Entrepreneurship Talents"Introduction Plan of Jiangsu Province in 2018.
文摘The composition of a slag system has been shown to be particularly important and influential for the new technology of electroslag remelting withdrawal process.The oxidation of the GH984G alloy elements,in contact with different contents of CaF_(2)–CaO–Al_(2)O_(3)–MgO–TiO_(2)–SiO_(2)in various slag systems,has been investigated in the present study by performing slag–metal equilibrium experiments and ion and molecule coexistence theory analysis.The results show that CaF_(2)and MgO have only a minor effect on the oxidation rates of Al and Ti in the GH984G superalloys.However,it was found that SiO_(2)would intensify the oxidation degree of Al and Ti,and Al was found to become easier oxidized than Ti.Moreover,CaO was found to reduce the activity of SiO_(2)and,thereby,also the oxidation degree of Al and Ti.Also,TiO_(2)was found to reduce the oxidation rate of Ti and instead increase the oxidation rate of Al.Finally,the effect of Al_(2)O_(3)on the oxidation of Al and Ti was observed to be opposite to that of TiO_(2).The calculated results were found to be in good agreement with experimental measurements.Moreover,viscosity experiments showed that CaO would rapidly increase the viscosity of the slag at low temperatures,and that the viscosity of the slag would increase with an increase in SiO_(2)content.
基金supported by Special funding project for research and development of key core technologies and common technologies in Shanxi Province(20201102017)supported by National Natural Science Foundations of China(Grant No.51874085 and 52274323)the Fundamental Research Funds for the Central Universities(Grant No.N2125030).
文摘A numerical model coupled with a multi-physical field based on dynamic formation of slag skin is established.After validation by comparing the experimental and simulation results of depth of metal pool,slag skin thickness and melt rate,it is utilized to investigate the effect of melt current on the coupled multi-physical field,slag skin thickness,metal pool depth and the heat flow distribution during electroslag remelting(ESR)Inconel 625 solidification process.The results showed that with the increase in the melt current,the velocities of ESR system and the temperature of metal pool increased,whereas the highest temperature of slag bath firstly decreased and then increased.With the increase in the melt current,the slag skin thickness,metal pool depth and melt rate increased.Furthermore,the characteristics of the heat flow distribution and the effect of melt current on the heat flow distribution were analysed.
