A 3D viscoelastic-plastic thermal-mechanical coupled finite element model was built on the basis of the secondary development of the commercial software MSC.Marc. Numerical simulations were performed to study slab bro...A 3D viscoelastic-plastic thermal-mechanical coupled finite element model was built on the basis of the secondary development of the commercial software MSC.Marc. Numerical simulations were performed to study slab broadening in the secondary cooling zone. The effects of slab width and thickness on slab broadening were considered. The obtained results reveal that the width broadening is noticeable, and the ratio of ultimate broadening slightly increases with the increase of slab width. This agrees well with the measured data in practice. There is no obvious increase in ultimate broadening when the thickness of slabs increases.展开更多
In this study,the effect of decarburization annealing temperature and time on the carbon content,microstructure,and texture of grain-oriented pure iron was investigated by optical microscopy and scanning electron micr...In this study,the effect of decarburization annealing temperature and time on the carbon content,microstructure,and texture of grain-oriented pure iron was investigated by optical microscopy and scanning electron microscopy with electron-backscatter diffraction. The results showed that the efficiency of decarburization dramatically increased with increasing decarburization temperature. However,when the annealing temperature was increased to 825°C and 850°C,the steel's carbon content remained essentially unchanged at 0.002%. With increasing decarburization time,the steel's carbon content generally decreased. When both the decarburization temperature and time were increased further,the average grain size dramatically increased and the number of fine grains decreased; meanwhile,some relatively larger grains developed. The main texture types of the decarburized sheets were approximately the same: {001}<110> and {112~115}<110>,with a γ-fiber texture. Furthermore,little change was observed in the texture. Compared with the experimental sheets,the texture of the cold-rolled sheet was very scattered. The best average magnetic induction(B_(800)) among the final products was 1.946 T.展开更多
In order to check the general existence of broadening of slab and the reasons of formation,the broadening of slab was investigated on the basis of several industrial manufactures of continuous casting.The results show...In order to check the general existence of broadening of slab and the reasons of formation,the broadening of slab was investigated on the basis of several industrial manufactures of continuous casting.The results show that slab broadening commonly exists in the process of continuous casting.The causes of broadening were ruled out of the consideration of the change of mold size or the change of technical parameters.The results reveal that the broadening of slab probably results from the static pressure of molten steel and the force from driving rolls.At the same time,online observations of three grades of steel in the process of continuous casting reveal that the ratio of ultimate broadening of slab ranges from 1.27% to 3.00%,and even arrives at 4.4%.展开更多
The mechanism of broadening of slab in continuous casting was studied by numerical simulations and experimental measurements in factories. The mechanism is derived by gradual exclusion of various factors related to th...The mechanism of broadening of slab in continuous casting was studied by numerical simulations and experimental measurements in factories. The mechanism is derived by gradual exclusion of various factors related to the broadening of slab. It is concluded that the slab exposes to no constraint at the direction of narrow face. Because of the static pressure of molten steel, the slab deforms creepily in the direction that consequently results in the broadening of slab. The broadening of slab increases with casting speed and static pressure of molten steel. The decrease of secondary cooling intensity and strength of steel at high temperature also contribute to the broadening of slab. The micro-alloying plays an important role in improving the strength of steel and in reducing the broadening of slab.展开更多
A computational model of thermal behavior of the top-surface slag layers in continuous casting mold was applied to interpret the thermal insulation of mold powder. The temperature drop of liquid steel caused by heat r...A computational model of thermal behavior of the top-surface slag layers in continuous casting mold was applied to interpret the thermal insulation of mold powder. The temperature drop of liquid steel caused by heat re moral at the interface of molten steel and slag in mold was proposed to evaluate the thermal insulation of mold slag. The calculation results show that slag consumption is one of important factor influencing the temperature drop, while the casting speed has no obvious effect on it. With the increase of slag consumption, the temperature drop is increased.展开更多
A micro-segregation model of solute elements in mushy zone with δ/γ transformation during solidification was established based on the regular hexagon transverse cross section of dendrite shape proposed by finite dif...A micro-segregation model of solute elements in mushy zone with δ/γ transformation during solidification was established based on the regular hexagon transverse cross section of dendrite shape proposed by finite difference method under the non-equilibrium solidification condition. The model was used to calculate the non-equilibrium pseudo binary Fe-C phase diagram and the strain of steels induced by variation of temperature in brittle temperature range. On the basis of the phase diagram and the strain, the strain curve in brittle temperature range as a function of carbon content for continuously fast strand was introduced and obtained, Solute elements change the position of the strain curve. And cooling rate changes the position arid the shape of the strain curve. The comprehensive formula of the strain as functions of solute elements and cooling rate in brittle temperature range has been obtained by nonlinear fitting program.展开更多
To improve the slab quality, a kind of non-sinusoidal oscillation technique of mold driven by elliptic gears was developed. The waveform functions of non-sinusoidal oscillation were determined, and the calculation met...To improve the slab quality, a kind of non-sinusoidal oscillation technique of mold driven by elliptic gears was developed. The waveform functions of non-sinusoidal oscillation were determined, and the calculation method and curves of technological parameters for non-sinusoidal oscillation were given. At the case of waveform deviation factor a equal to 0.31 and oscillation amplitude h equal to ±2.7 mm, the relationship between oscillation frequency and casting speed is determined, and the technological parameters for non-sinusoidal oscillation are calculated. The testing results of industrial application indicated that this technique could not only improve the Slab surface quality, but also reduce the steel breakout.展开更多
Combining with the study of analogue experiments and test analysis, the kinetics of precipitation and growth of AlN and MnS in non-oriented electrical steel produced by the CSP process is calculated. The results show ...Combining with the study of analogue experiments and test analysis, the kinetics of precipitation and growth of AlN and MnS in non-oriented electrical steel produced by the CSP process is calculated. The results show that the precipitate phase particles of AlN and MnS in typical non-oriented electrical steel grades produced by the CSP process have grown to some extent in the soaking stage, but the precipitation contents are less than 20% of the total contents of nitride and sulfide. The precipitate phase particles of AlN and MnS have precipitated almost after the hot rolling process. The precipitation contents are more than 80% of the total contents of nitride and sulfide, but it is very late for the precipitate phase particles to grow at the end of the hot rolling process.展开更多
The grain-oriented silicon steel is a kind of important magnetic materials with low iron loss and high induc tion. Hot hand normalizing annealing is an important process which influences the microstructure and the dev...The grain-oriented silicon steel is a kind of important magnetic materials with low iron loss and high induc tion. Hot hand normalizing annealing is an important process which influences the microstructure and the development of the inhibitors. The effects of different annealing temperatures and cooling conditions on the inhibitors and microstructures of normalizing annealing band were investigated. The microstructure and different kinds of the inhibitors, i. e. , A1N, AIN＋Cu, S＋MnS, and TiN, were discovered. The result shows that a suitable cooling condition leads to more nano scale inhibitors and uniform microstructure of the normalizing annealing band and consequently results in better magnetic properties.展开更多
The surface oxide layer of grain-oriented electrical steels was investigated by scanning electron microscopy.The formation mechanism and the influence on the glass film of the surface oxide layer were analyzed by the ...The surface oxide layer of grain-oriented electrical steels was investigated by scanning electron microscopy.The formation mechanism and the influence on the glass film of the surface oxide layer were analyzed by the calculation of thermodynamics and kinetics.The surface oxide layer with 2.3μm in thickness is mainly composed of SiO_(2),a small amount of FeO and Fe_(2)SiO_(4).During the formation of surface oxide layer,the restriction factor was the diffusion of O in the oxide layer.At the initial stage of the decarburization annealing,FeO would be formed on the surface layer.SiO_(2) and silicate particles rapidly nucleated,grew and formed a granular oxide layer in the subsurface.As the oxidation layer thickens,the nucleation of new particles decreases,and the growth of oxide particles would be dominant.A lamellar oxide layer was formed between the surface oxide layer and the steel matrix,and eventually formed a typical three-layer structure.During the high temperature annealing,MgO mainly reacted with SiO_(2) and Fe_(2)SiO_(4) in the surface oxide layer to form Mg2SiO_(4) and Fe_(2)SiO_(4) would respond first,thus forming the glass film with average thickness of 4.87μm.展开更多
The effect of nitrogen content on primary recrystallization microstructure,texture and magnetic property of Hi-B steel was studied by means of optical microscopy（OM）,scanning electron microscopy（SEM）,and electron ...The effect of nitrogen content on primary recrystallization microstructure,texture and magnetic property of Hi-B steel was studied by means of optical microscopy（OM）,scanning electron microscopy（SEM）,and electron backscatter diffraction（EBSD）.When nitrogen content increased gradually from 0.005 5% to 0.031 0%,the primary grain size and variation coefficient of nitrided sheet reduced from 26.85μm,0.590 to 18.87μm,0.525-0.565,respectively.Meanwhile,the primary recrystallization texture style of nitrided sheet was nearly identical to the texture style of decarburized sheet before nitriding treatment,but exhibiting a certain change on texture intensity.The variation of average magnetic induction value（B8）and core loss value（P17/50）were manifested to be Mshaped and W-shaped curves,respectively.When nitrogen content reached 0.016 0%,the best value of the average magnetic property of the final product was obtained as follows：the B8 and P17/50 were 1.921 Tand 0.968W/kg,respectively.Meanwhile,the best performance,B8 and P17/50,of single sheet was 1.964 Tand 0.854 W/kg.展开更多
To promote the manufacture of grain-oriented pure iron, the texture and inhibitor features of two samples A and B produced by different cold-rolling processes were studied by optical microscopy, X-ray diffraction, and...To promote the manufacture of grain-oriented pure iron, the texture and inhibitor features of two samples A and B produced by different cold-rolling processes were studied by optical microscopy, X-ray diffraction, and transmission electron microscopy. The results showed that a higher content of inhibitor elements directly resulted in a greater number of fine inhibitors, which exhibited strong inhibitory ability, leading to more fine precipitates of appropriate size effectively inhibiting the growth of primary grains in decarburized bands （sheets） during the single-stage cold-rolling process. The formation of the component with { 110}〈001〉 Goss orientation was greatly suppressed in the stage of primary recrystallization, and this component could hardly be observed in the decarburized band; by contrast, the {411 }〈148〉-oriented grains grew. During the process of high-temperature annealing, abnormal growth occurred and secondary recrystallized grains （Goss orientation） merged with other matrix grains such as { 111 }〈112〉 and {411 }〈148〉. The magnetic induction of samples A and B at 800 Aim was 1.939 T and 1.996 T, respectively.展开更多
According to the analysis related to kinetic mechanism of vacuum denitrogenation and combining with the actual production of RH-MFB （a combination of Ruhstahl-Hausen vacuum degassing process with a multifunctional ox...According to the analysis related to kinetic mechanism of vacuum denitrogenation and combining with the actual production of RH-MFB （a combination of Ruhstahl-Hausen vacuum degassing process with a multifunctional oxygen lance） at Liansteel, the limit step and model equation of vacuum denitrogenation are determined. Meanwhile, the influencing factors of nitrogen removal from liquid steel in vacuum of RH-MFB are analyzed. The results show that the limit step of vacuum denitrogenation in RH-MFB is the mass transfer of nitrogen in liquid boundary layer and the reaction follows first order kinetics. Keeping the necessary circulation time under the working pressure （67 Pa） is helpful to nitrogen removal from steel. The oxygen content in molten steel has little influence on the removal of ni-trogen after deep deoxidation, while the sulphur content in liquid steel is always relatively low and has little effect on denitrogenation. The sharp decrease of carbon content in steel drives the process of denitrogenation reaction so as to exhibit a faster denitrogenation rate. The interracial chemical reaction and argon blowing play a major role in the ni-trogen removal when the carbon content in liquid steel is stable.展开更多
How to manufacture the high magnetic induction grain-oriented silicon steel（Hi-B steel）by the process featured with the primary recrystallization annealing was demonstrated,during which nitriding and decarburizing w...How to manufacture the high magnetic induction grain-oriented silicon steel（Hi-B steel）by the process featured with the primary recrystallization annealing was demonstrated,during which nitriding and decarburizing were simultaneously realized in laboratory.By the techniques of optical microscope,scanning electronic microscope and electron backscattered diffraction,both the microstructure and the texture in the samples were characterized.The samples had been subjected to nitriding to different nitrogen contents at two specified temperatures using the two defined microstructural parameters：the grain size inhomogeneity factorσ＊and the texture factor AR.The former is the ratio of the mean value to standard deviation of grain sizes;the latter is the ratio of the total volume fraction of the harmful textures to that of beneficial textures including {110}〈001〉.When the N content increased from 0.0055%to 0.0330%after the annealing at both 835 and 875°C,the resultant recrystallized grain size decreased butσ＊changed little;whilst the rise of annealing temperature from 835 to 875°C resulted in the increase in both grain size andσ＊.Moreover,either the injected N content or temperature had insignificant influence on the components of primary recrystallization texture developed during annealing.However,the increase of temperature led to the decreases in both intensity and volume fraction of{001}〈120〉and{110}〈001〉textures but increases in the{114}〈481〉andγfiber textures and the resultant decrease of AR.展开更多
The effects of temperature and alloying elements on γ phase fraction of grain-oriented silicon steel,which contained 2.97-3.42mass% Si and 0.028-0.058mass% C,were studied by microstructure observation and statistics....The effects of temperature and alloying elements on γ phase fraction of grain-oriented silicon steel,which contained 2.97-3.42mass% Si and 0.028-0.058mass% C,were studied by microstructure observation and statistics.Furthermore,the quantitative relationships of temperature as well as C,Si,and Mn contents to γ phase fraction were obtained by numerical fitting.The experimental results show that γ phase fraction firstly increases with increasing temperature,reaches a maximum and then decreases in the temperature range of 900-1 250 ℃.The temperature corresponding to the maximum γ phase fraction is about 1 150-1 200℃.Meanwhile,the γ phase fractions in steels at the same temperature have some differences because of different contents of various alloying elements.The verification results show that the values of γ phase fractions to C,Si,and Mn contents at the specific temperatures,which were obtained by multiple linear regression method,agree well with the measured values.In addition,the values of γ phase fractions to C,Si,and Mn contents in the temperature range of 900-1 250℃,which were obtained by binomial regression method,agree with the measured values when the contents of Mn and soluble Al are not more than 0.320mass% and 0.034mass%,respectively.The obtained equations can carry out the approximate prediction of γ phase fractions of grain-oriented silicon steels during the hot rolling process.展开更多
Nozzle cooling equipment is developed to supervise and control the heat flux by changing water flux. An in- dustrial experiment is held in billet caster in Huaigang . The results show that cooling control system works...Nozzle cooling equipment is developed to supervise and control the heat flux by changing water flux. An in- dustrial experiment is held in billet caster in Huaigang . The results show that cooling control system works stably and effectively to control the heat fluxes by the temperature of copper tube. The superheat of steel in mould is reduced and the equiaxed crystal ratio, as well as compact degree of steel is raised.展开更多
According to the ion and molecule coexistence theory, the activity model of Al2O3- BaO-B2O3 ternary slag system was established, and the influences of BaO/Al2O3 molar ratio, B2O3 mole fraction and temperature on the a...According to the ion and molecule coexistence theory, the activity model of Al2O3- BaO-B2O3 ternary slag system was established, and the influences of BaO/Al2O3 molar ratio, B2O3 mole fraction and temperature on the activity of the slag system were investigated. Finally, the equal activity curves were drawn with the model results. The results show that with the increase of BaO/Al2O3 ratio, the activity of Al2O3 is significantly reduced, the activi- ty of BaO3-Al2O3 is increased obviously, and the activity of 2Al2O3· B2O3 is also decreased. With the increase of B2O3 mole fraction, the activity of BaO · Al2O3 decreased significantly, while the activities of BaO·B2O3 and 2Al2O3·B2O3 increased. In addition, the influence of temperature on the activities of different components is com paratively smaller than the influence of BaO/Al2O3 ratio and B2O3 mole fraction.展开更多
基金supported by the Key Projects in the National Science & Technology Pillar Program during the 11th Five-Year Plan Period of China (No.2006BAE03A04)
文摘A 3D viscoelastic-plastic thermal-mechanical coupled finite element model was built on the basis of the secondary development of the commercial software MSC.Marc. Numerical simulations were performed to study slab broadening in the secondary cooling zone. The effects of slab width and thickness on slab broadening were considered. The obtained results reveal that the width broadening is noticeable, and the ratio of ultimate broadening slightly increases with the increase of slab width. This agrees well with the measured data in practice. There is no obvious increase in ultimate broadening when the thickness of slabs increases.
文摘In this study,the effect of decarburization annealing temperature and time on the carbon content,microstructure,and texture of grain-oriented pure iron was investigated by optical microscopy and scanning electron microscopy with electron-backscatter diffraction. The results showed that the efficiency of decarburization dramatically increased with increasing decarburization temperature. However,when the annealing temperature was increased to 825°C and 850°C,the steel's carbon content remained essentially unchanged at 0.002%. With increasing decarburization time,the steel's carbon content generally decreased. When both the decarburization temperature and time were increased further,the average grain size dramatically increased and the number of fine grains decreased; meanwhile,some relatively larger grains developed. The main texture types of the decarburized sheets were approximately the same: {001}<110> and {112~115}<110>,with a γ-fiber texture. Furthermore,little change was observed in the texture. Compared with the experimental sheets,the texture of the cold-rolled sheet was very scattered. The best average magnetic induction(B_(800)) among the final products was 1.946 T.
基金Item Sponsored by National Science and Technology Support Program for 11th Five-Year Plan of China(2006BAE03A04)
文摘In order to check the general existence of broadening of slab and the reasons of formation,the broadening of slab was investigated on the basis of several industrial manufactures of continuous casting.The results show that slab broadening commonly exists in the process of continuous casting.The causes of broadening were ruled out of the consideration of the change of mold size or the change of technical parameters.The results reveal that the broadening of slab probably results from the static pressure of molten steel and the force from driving rolls.At the same time,online observations of three grades of steel in the process of continuous casting reveal that the ratio of ultimate broadening of slab ranges from 1.27% to 3.00%,and even arrives at 4.4%.
基金supported by the Key Projects in the National Science & Technology Pillar Program during the Eleventh Five-Year Plan of China(Grant No. 2006BAE03A04)
文摘The mechanism of broadening of slab in continuous casting was studied by numerical simulations and experimental measurements in factories. The mechanism is derived by gradual exclusion of various factors related to the broadening of slab. It is concluded that the slab exposes to no constraint at the direction of narrow face. Because of the static pressure of molten steel, the slab deforms creepily in the direction that consequently results in the broadening of slab. The broadening of slab increases with casting speed and static pressure of molten steel. The decrease of secondary cooling intensity and strength of steel at high temperature also contribute to the broadening of slab. The micro-alloying plays an important role in improving the strength of steel and in reducing the broadening of slab.
文摘A computational model of thermal behavior of the top-surface slag layers in continuous casting mold was applied to interpret the thermal insulation of mold powder. The temperature drop of liquid steel caused by heat re moral at the interface of molten steel and slag in mold was proposed to evaluate the thermal insulation of mold slag. The calculation results show that slag consumption is one of important factor influencing the temperature drop, while the casting speed has no obvious effect on it. With the increase of slag consumption, the temperature drop is increased.
基金Item Sponsored by National Basic Research Program of China(2010CB630806-2)
文摘A micro-segregation model of solute elements in mushy zone with δ/γ transformation during solidification was established based on the regular hexagon transverse cross section of dendrite shape proposed by finite difference method under the non-equilibrium solidification condition. The model was used to calculate the non-equilibrium pseudo binary Fe-C phase diagram and the strain of steels induced by variation of temperature in brittle temperature range. On the basis of the phase diagram and the strain, the strain curve in brittle temperature range as a function of carbon content for continuously fast strand was introduced and obtained, Solute elements change the position of the strain curve. And cooling rate changes the position arid the shape of the strain curve. The comprehensive formula of the strain as functions of solute elements and cooling rate in brittle temperature range has been obtained by nonlinear fitting program.
基金Item Sponsored by National Natural Science Foundation of China(51275446)National Natural Science Foundation of China and Baosteel Group Co.,Ltd.(U1260203)Natural Science Foundation of Hebei Province of China(E2012203080)
文摘To improve the slab quality, a kind of non-sinusoidal oscillation technique of mold driven by elliptic gears was developed. The waveform functions of non-sinusoidal oscillation were determined, and the calculation method and curves of technological parameters for non-sinusoidal oscillation were given. At the case of waveform deviation factor a equal to 0.31 and oscillation amplitude h equal to ±2.7 mm, the relationship between oscillation frequency and casting speed is determined, and the technological parameters for non-sinusoidal oscillation are calculated. The testing results of industrial application indicated that this technique could not only improve the Slab surface quality, but also reduce the steel breakout.
基金Mega-Projects of Science Research for the 10th Five-Year Plan (2004BA318B)
文摘Combining with the study of analogue experiments and test analysis, the kinetics of precipitation and growth of AlN and MnS in non-oriented electrical steel produced by the CSP process is calculated. The results show that the precipitate phase particles of AlN and MnS in typical non-oriented electrical steel grades produced by the CSP process have grown to some extent in the soaking stage, but the precipitation contents are less than 20% of the total contents of nitride and sulfide. The precipitate phase particles of AlN and MnS have precipitated almost after the hot rolling process. The precipitation contents are more than 80% of the total contents of nitride and sulfide, but it is very late for the precipitate phase particles to grow at the end of the hot rolling process.
基金Item Sponsored by National Science Fund and Baosteel Joint Funding of China(50934009)
文摘The grain-oriented silicon steel is a kind of important magnetic materials with low iron loss and high induc tion. Hot hand normalizing annealing is an important process which influences the microstructure and the development of the inhibitors. The effects of different annealing temperatures and cooling conditions on the inhibitors and microstructures of normalizing annealing band were investigated. The microstructure and different kinds of the inhibitors, i. e. , A1N, AIN＋Cu, S＋MnS, and TiN, were discovered. The result shows that a suitable cooling condition leads to more nano scale inhibitors and uniform microstructure of the normalizing annealing band and consequently results in better magnetic properties.
基金Financial supports from National Key Research and Development Program(No.2016YFB0300305)National Natural Science Foundation of China(No.51804003)are gratefully acknowledged.
文摘The surface oxide layer of grain-oriented electrical steels was investigated by scanning electron microscopy.The formation mechanism and the influence on the glass film of the surface oxide layer were analyzed by the calculation of thermodynamics and kinetics.The surface oxide layer with 2.3μm in thickness is mainly composed of SiO_(2),a small amount of FeO and Fe_(2)SiO_(4).During the formation of surface oxide layer,the restriction factor was the diffusion of O in the oxide layer.At the initial stage of the decarburization annealing,FeO would be formed on the surface layer.SiO_(2) and silicate particles rapidly nucleated,grew and formed a granular oxide layer in the subsurface.As the oxidation layer thickens,the nucleation of new particles decreases,and the growth of oxide particles would be dominant.A lamellar oxide layer was formed between the surface oxide layer and the steel matrix,and eventually formed a typical three-layer structure.During the high temperature annealing,MgO mainly reacted with SiO_(2) and Fe_(2)SiO_(4) in the surface oxide layer to form Mg2SiO_(4) and Fe_(2)SiO_(4) would respond first,thus forming the glass film with average thickness of 4.87μm.
基金Item Sponsored by National Natural Science Foundation of China(50934009)
文摘The effect of nitrogen content on primary recrystallization microstructure,texture and magnetic property of Hi-B steel was studied by means of optical microscopy（OM）,scanning electron microscopy（SEM）,and electron backscatter diffraction（EBSD）.When nitrogen content increased gradually from 0.005 5% to 0.031 0%,the primary grain size and variation coefficient of nitrided sheet reduced from 26.85μm,0.590 to 18.87μm,0.525-0.565,respectively.Meanwhile,the primary recrystallization texture style of nitrided sheet was nearly identical to the texture style of decarburized sheet before nitriding treatment,but exhibiting a certain change on texture intensity.The variation of average magnetic induction value（B8）and core loss value（P17/50）were manifested to be Mshaped and W-shaped curves,respectively.When nitrogen content reached 0.016 0%,the best value of the average magnetic property of the final product was obtained as follows：the B8 and P17/50 were 1.921 Tand 0.968W/kg,respectively.Meanwhile,the best performance,B8 and P17/50,of single sheet was 1.964 Tand 0.854 W/kg.
基金This work was financially supported by the National Natural Science Foundation of China （No. 51804003）.
文摘To promote the manufacture of grain-oriented pure iron, the texture and inhibitor features of two samples A and B produced by different cold-rolling processes were studied by optical microscopy, X-ray diffraction, and transmission electron microscopy. The results showed that a higher content of inhibitor elements directly resulted in a greater number of fine inhibitors, which exhibited strong inhibitory ability, leading to more fine precipitates of appropriate size effectively inhibiting the growth of primary grains in decarburized bands （sheets） during the single-stage cold-rolling process. The formation of the component with { 110}〈001〉 Goss orientation was greatly suppressed in the stage of primary recrystallization, and this component could hardly be observed in the decarburized band; by contrast, the {411 }〈148〉-oriented grains grew. During the process of high-temperature annealing, abnormal growth occurred and secondary recrystallized grains （Goss orientation） merged with other matrix grains such as { 111 }〈112〉 and {411 }〈148〉. The magnetic induction of samples A and B at 800 Aim was 1.939 T and 1.996 T, respectively.
文摘According to the analysis related to kinetic mechanism of vacuum denitrogenation and combining with the actual production of RH-MFB （a combination of Ruhstahl-Hausen vacuum degassing process with a multifunctional oxygen lance） at Liansteel, the limit step and model equation of vacuum denitrogenation are determined. Meanwhile, the influencing factors of nitrogen removal from liquid steel in vacuum of RH-MFB are analyzed. The results show that the limit step of vacuum denitrogenation in RH-MFB is the mass transfer of nitrogen in liquid boundary layer and the reaction follows first order kinetics. Keeping the necessary circulation time under the working pressure （67 Pa） is helpful to nitrogen removal from steel. The oxygen content in molten steel has little influence on the removal of ni-trogen after deep deoxidation, while the sulphur content in liquid steel is always relatively low and has little effect on denitrogenation. The sharp decrease of carbon content in steel drives the process of denitrogenation reaction so as to exhibit a faster denitrogenation rate. The interracial chemical reaction and argon blowing play a major role in the ni-trogen removal when the carbon content in liquid steel is stable.
基金financially sponsored by the State Key Special Project of Key Basic Material Technical Promotion and Industrialization(2016YFB0300305)
文摘How to manufacture the high magnetic induction grain-oriented silicon steel（Hi-B steel）by the process featured with the primary recrystallization annealing was demonstrated,during which nitriding and decarburizing were simultaneously realized in laboratory.By the techniques of optical microscope,scanning electronic microscope and electron backscattered diffraction,both the microstructure and the texture in the samples were characterized.The samples had been subjected to nitriding to different nitrogen contents at two specified temperatures using the two defined microstructural parameters：the grain size inhomogeneity factorσ＊and the texture factor AR.The former is the ratio of the mean value to standard deviation of grain sizes;the latter is the ratio of the total volume fraction of the harmful textures to that of beneficial textures including {110}〈001〉.When the N content increased from 0.0055%to 0.0330%after the annealing at both 835 and 875°C,the resultant recrystallized grain size decreased butσ＊changed little;whilst the rise of annealing temperature from 835 to 875°C resulted in the increase in both grain size andσ＊.Moreover,either the injected N content or temperature had insignificant influence on the components of primary recrystallization texture developed during annealing.However,the increase of temperature led to the decreases in both intensity and volume fraction of{001}〈120〉and{110}〈001〉textures but increases in the{114}〈481〉andγfiber textures and the resultant decrease of AR.
基金Item Sponsored by National Natural Science Foundation of China(50934009)
文摘The effects of temperature and alloying elements on γ phase fraction of grain-oriented silicon steel,which contained 2.97-3.42mass% Si and 0.028-0.058mass% C,were studied by microstructure observation and statistics.Furthermore,the quantitative relationships of temperature as well as C,Si,and Mn contents to γ phase fraction were obtained by numerical fitting.The experimental results show that γ phase fraction firstly increases with increasing temperature,reaches a maximum and then decreases in the temperature range of 900-1 250 ℃.The temperature corresponding to the maximum γ phase fraction is about 1 150-1 200℃.Meanwhile,the γ phase fractions in steels at the same temperature have some differences because of different contents of various alloying elements.The verification results show that the values of γ phase fractions to C,Si,and Mn contents at the specific temperatures,which were obtained by multiple linear regression method,agree well with the measured values.In addition,the values of γ phase fractions to C,Si,and Mn contents in the temperature range of 900-1 250℃,which were obtained by binomial regression method,agree with the measured values when the contents of Mn and soluble Al are not more than 0.320mass% and 0.034mass%,respectively.The obtained equations can carry out the approximate prediction of γ phase fractions of grain-oriented silicon steels during the hot rolling process.
基金Item Sponsored by State Key Development Program of Basic Research of China(2004CB619107)
文摘Nozzle cooling equipment is developed to supervise and control the heat flux by changing water flux. An in- dustrial experiment is held in billet caster in Huaigang . The results show that cooling control system works stably and effectively to control the heat fluxes by the temperature of copper tube. The superheat of steel in mould is reduced and the equiaxed crystal ratio, as well as compact degree of steel is raised.
文摘According to the ion and molecule coexistence theory, the activity model of Al2O3- BaO-B2O3 ternary slag system was established, and the influences of BaO/Al2O3 molar ratio, B2O3 mole fraction and temperature on the activity of the slag system were investigated. Finally, the equal activity curves were drawn with the model results. The results show that with the increase of BaO/Al2O3 ratio, the activity of Al2O3 is significantly reduced, the activi- ty of BaO3-Al2O3 is increased obviously, and the activity of 2Al2O3· B2O3 is also decreased. With the increase of B2O3 mole fraction, the activity of BaO · Al2O3 decreased significantly, while the activities of BaO·B2O3 and 2Al2O3·B2O3 increased. In addition, the influence of temperature on the activities of different components is com paratively smaller than the influence of BaO/Al2O3 ratio and B2O3 mole fraction.
