In the hot rolling process, the hot crown of the roll is determined by the roll temperature and the temperature distribution. Furthermore, the hot crown is an important factor, which causes variation in the strip gage along the plane perpendicular to the rolling direction, affecting the strip quality. However, the roll temperature response has the characteristics of nonlinearity, hysteresis and time-varying, which makes it difficult to control accurately by classical control theory and method. In order to accurately control the rolling temperature, a variable universe fuzzy controller based on improved cat swarm optimization (ICSO-VUFC) was established. Firstly, a dynamic mixture ratio and an improved tracking mode were used to improve the optimization capability of the cat swarm. In comparison with the conventional cat swarm optimization (CSO) controller, the proposed process showed better optimization performance. Secondly, a simulation analysis based on MATLAB was employed to compare the ICSO-VUFC with the conventional fuzzy controller (C-FC) and the fuzzy controller based on the improved cat swarm optimization (ICSO-FC). The results reveal that the ICSO-VUFC exhibits the best dynamic and steady performance. Finally, the temperature control accuracy of the rolled regions during different rolling passes under the three fuzzy controllers was examined and compared. The results show that the ICSO-VUFC exhibits the highest control accuracy and stability with a temperature error range of ±4 °C. Through the analysis of the strip crown, it can be seen that the control accuracy of the strip crown can be effectively improved by using ICSO-VUFC to control the roll temperature distribution.
{"title":"Research on roll temperature compensation of variable domain fuzzy controller based on improved cat swarm optimization","authors":"Shanfeng Gao, Le Lei","doi":"10.1051/metal/2023087","DOIUrl":"https://doi.org/10.1051/metal/2023087","url":null,"abstract":"In the hot rolling process, the hot crown of the roll is determined by the roll temperature and the temperature distribution. Furthermore, the hot crown is an important factor, which causes variation in the strip gage along the plane perpendicular to the rolling direction, affecting the strip quality. However, the roll temperature response has the characteristics of nonlinearity, hysteresis and time-varying, which makes it difficult to control accurately by classical control theory and method. In order to accurately control the rolling temperature, a variable universe fuzzy controller based on improved cat swarm optimization (ICSO-VUFC) was established. Firstly, a dynamic mixture ratio and an improved tracking mode were used to improve the optimization capability of the cat swarm. In comparison with the conventional cat swarm optimization (CSO) controller, the proposed process showed better optimization performance. Secondly, a simulation analysis based on MATLAB was employed to compare the ICSO-VUFC with the conventional fuzzy controller (C-FC) and the fuzzy controller based on the improved cat swarm optimization (ICSO-FC). The results reveal that the ICSO-VUFC exhibits the best dynamic and steady performance. Finally, the temperature control accuracy of the rolled regions during different rolling passes under the three fuzzy controllers was examined and compared. The results show that the ICSO-VUFC exhibits the highest control accuracy and stability with a temperature error range of ±4 °C. Through the analysis of the strip crown, it can be seen that the control accuracy of the strip crown can be effectively improved by using ICSO-VUFC to control the roll temperature distribution.","PeriodicalId":370509,"journal":{"name":"Metallurgical Research & Technology","volume":"3 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138944220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article uses Sn as the metal flux and CaF2-CaO as the reference slag to experimentally measure the activity of CaO at T = 1773∼1873 K. The effects of different w(Al2O3) and temperature(T) on CaO activity were investigated. The results are as follows: when w(MgO) = 6%, R(w(CaO)/w(SiO2)) = 1.20, w(Al2O3) = 12%, 14%, 16% and 18%, with the increase of w(Al2O3), the activity and activity coefficient of CaO in slag gradually decrease; with the increase of temperature (T), the activity and activity coefficient of CaO in slag gradually increase; the activity coefficient of Ca in Sn decrease with increasing temperature.
本文以 Sn 为金属助熔剂，CaF2-CaO 为基准渣，在 T = 1773∼1873 K 条件下实验测定了 CaO 的活性，研究了不同 w(Al2O3) 和温度（T）对 CaO 活性的影响。结果如下：当 w(MgO) = 6%，R(w(CaO)/w(SiO2)) = 1.20，w(Al2O3) = 12%、14%、16% 和 18%时，随着 w(Al2O3) 的增加，熔渣中 CaO 的活性和活性系数逐渐降低；随着温度（T）的增加，熔渣中 CaO 的活性和活性系数逐渐增加；随着温度的增加，锡中 Ca 的活性系数降低。
{"title":"Research on thermodynamic characteristics of metallurgical slag","authors":"Yongchun Guo, Mengyao Li","doi":"10.1051/metal/2023084","DOIUrl":"https://doi.org/10.1051/metal/2023084","url":null,"abstract":"This article uses Sn as the metal flux and CaF2-CaO as the reference slag to experimentally measure the activity of CaO at T = 1773∼1873 K. The effects of different w(Al2O3) and temperature(T) on CaO activity were investigated. The results are as follows: when w(MgO) = 6%, R(w(CaO)/w(SiO2)) = 1.20, w(Al2O3) = 12%, 14%, 16% and 18%, with the increase of w(Al2O3), the activity and activity coefficient of CaO in slag gradually decrease; with the increase of temperature (T), the activity and activity coefficient of CaO in slag gradually increase; the activity coefficient of Ca in Sn decrease with increasing temperature.","PeriodicalId":370509,"journal":{"name":"Metallurgical Research & Technology","volume":" 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138962196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Song Zhang, Maoqiang Gu, Yanbing Zong, Zhenyang Wang, Jianliang Zhang, Dewen Jiang, Jing Pang, Shushi Zhang, Ruishuai Si
Blast furnace smelting is a traditional iron-making process. Its product, hot metal, is an important raw material for the production of steel. Steelmaking efficiency can be improved and steel product quality can be stabilized by using proper hot metal. Sulfur is an important indicator reflecting the quality of hot metal, it is necessary to establish an accurate prediction model to predict the sulfur content of hot metal, to effectively guide the production process. There is a non-linear relationship among the factors influencing the desulfurization effect during the blast furnace smelting process, and the back propagation neural network (BPNN) model has a strong ability to solve nonlinear problems. However, BPNN has the disadvantages of slow convergence speed and easy to fall into local minima. To improve the prediction accuracy, an improved algorithm combining Kmeans and BPNN is proposed in this paper. The study showed that compared with the BPNN model and case-based reasoning (CBR) model, the Kmeans-BPNN model has the lowest RMSE and MAPE values, which indicates a high degree of fit and a low degree of dispersion. The Kmeans-BPNN model has the largest HR value, which indicates the highest prediction accuracy. The proposed Kmeans-BPNN prediction model achieves a hit rate of 96%, which is 4.5% higher than before the improvement. It can effectively improve the prediction accuracy of hot metal sulfur content.
{"title":"Improved back propagation neural network method for predicting sulfur content in hot metal","authors":"Song Zhang, Maoqiang Gu, Yanbing Zong, Zhenyang Wang, Jianliang Zhang, Dewen Jiang, Jing Pang, Shushi Zhang, Ruishuai Si","doi":"10.1051/metal/2023080","DOIUrl":"https://doi.org/10.1051/metal/2023080","url":null,"abstract":"Blast furnace smelting is a traditional iron-making process. Its product, hot metal, is an important raw material for the production of steel. Steelmaking efficiency can be improved and steel product quality can be stabilized by using proper hot metal. Sulfur is an important indicator reflecting the quality of hot metal, it is necessary to establish an accurate prediction model to predict the sulfur content of hot metal, to effectively guide the production process. There is a non-linear relationship among the factors influencing the desulfurization effect during the blast furnace smelting process, and the back propagation neural network (BPNN) model has a strong ability to solve nonlinear problems. However, BPNN has the disadvantages of slow convergence speed and easy to fall into local minima. To improve the prediction accuracy, an improved algorithm combining Kmeans and BPNN is proposed in this paper. The study showed that compared with the BPNN model and case-based reasoning (CBR) model, the Kmeans-BPNN model has the lowest RMSE and MAPE values, which indicates a high degree of fit and a low degree of dispersion. The Kmeans-BPNN model has the largest HR value, which indicates the highest prediction accuracy. The proposed Kmeans-BPNN prediction model achieves a hit rate of 96%, which is 4.5% higher than before the improvement. It can effectively improve the prediction accuracy of hot metal sulfur content.","PeriodicalId":370509,"journal":{"name":"Metallurgical Research & Technology","volume":"39 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139173010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ming-Lang Tseng, Muhammad I. Aslam, Emad A. A. Ismail, Fuad A. Awwad, N. Gorji
Heat treatment is vital for improving the characteristics of Laser Powder Bed Fusion (LPBF) components. The technique has the potential to change the microstructure of the material as well as its mechanical properties, such as yield strength, hardness, and ultimate tensile strength. To avoid undesirable impacts on the microstructure, temperature, heating, and cooling rates must be precisely controlled. Several parts were printed using LPBF from Steel 316L powder and went through post-process heating. The CT scan analysis revealed that heating the 3D printed parts for 40 min at 900 °C and 950 °C increased the porosity level across the parts although the porosity then decreased after 950 °C. From 850 °C to 1050 °C, EBSD analysis resulted in inverted pole figure maps demonstrating a relative increase in grain size. ImageJ software was used to determine the actual grain size and phase, revealing a grain size growth. Furthermore, as heat treatment temperatures increased, the ferrite phase enlarged. The cellular structure and high temperatures had a major impact on mechanical characteristics. Hardness test findings revealed a decreased mechanical characteristic as heat treatment temperature rose represented by increased porosity population and grain size. To increase the mechanical properties of these materials, an effective strategy is to achieve an even distribution of micro grains while limiting the porosity population.
{"title":"CT scan, EBSD and nanoindentation analysis of 3D-printed parts with post-process heat-treatment","authors":"Ming-Lang Tseng, Muhammad I. Aslam, Emad A. A. Ismail, Fuad A. Awwad, N. Gorji","doi":"10.1051/metal/2023083","DOIUrl":"https://doi.org/10.1051/metal/2023083","url":null,"abstract":"Heat treatment is vital for improving the characteristics of Laser Powder Bed Fusion (LPBF) components. The technique has the potential to change the microstructure of the material as well as its mechanical properties, such as yield strength, hardness, and ultimate tensile strength. To avoid undesirable impacts on the microstructure, temperature, heating, and cooling rates must be precisely controlled. Several parts were printed using LPBF from Steel 316L powder and went through post-process heating. The CT scan analysis revealed that heating the 3D printed parts for 40 min at 900 °C and 950 °C increased the porosity level across the parts although the porosity then decreased after 950 °C. From 850 °C to 1050 °C, EBSD analysis resulted in inverted pole figure maps demonstrating a relative increase in grain size. ImageJ software was used to determine the actual grain size and phase, revealing a grain size growth. Furthermore, as heat treatment temperatures increased, the ferrite phase enlarged. The cellular structure and high temperatures had a major impact on mechanical characteristics. Hardness test findings revealed a decreased mechanical characteristic as heat treatment temperature rose represented by increased porosity population and grain size. To increase the mechanical properties of these materials, an effective strategy is to achieve an even distribution of micro grains while limiting the porosity population.","PeriodicalId":370509,"journal":{"name":"Metallurgical Research & Technology","volume":"21 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138596676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ludwigite is a multi-element coexisting iron ore. Through the sinter pot experiment, the effect of ludwigite on the metallurgical properties of the sinter is studied, and its action mechanism is revealed combined with X-ray diffraction (XRD) analysis. The appropriate amount of ludwigite is obtained on the evaluation mechanism of softening and melting properties of the sinter, which provides theoretical guidance for practical production. The results show that with the increase of the amount of ludwigite, the yield, vertical sintering speed, and drum index in the metallurgical properties of the sinter show a gradual downward trend, and the low-temperature reduction pulverization index RDI+3.15 shows a gradual upward trend. The addition of ludwigite is conducive to the formation of calcium ferrite and promotes the activity of MgO. The addition of excessive ludwigite will lead to the formation of Mg2B2O5 and Ca3B2O6, Slag phase is formed. With the increase of the proportion of ludwigite, the melting range of the sinter is slightly widened, and the permeability is improved first and then reduced. Under this ore blending condition, ludwigite resources can be added and used in sintering batching, and the proportion shall not exceed 6%.
{"title":"Effect of ludwigite on sintering and metallurgical properties","authors":"Hua-bin Gao, Zhenggen Liu, Mansheng Chu, Jue Tang","doi":"10.1051/metal/2023082","DOIUrl":"https://doi.org/10.1051/metal/2023082","url":null,"abstract":"Ludwigite is a multi-element coexisting iron ore. Through the sinter pot experiment, the effect of ludwigite on the metallurgical properties of the sinter is studied, and its action mechanism is revealed combined with X-ray diffraction (XRD) analysis. The appropriate amount of ludwigite is obtained on the evaluation mechanism of softening and melting properties of the sinter, which provides theoretical guidance for practical production. The results show that with the increase of the amount of ludwigite, the yield, vertical sintering speed, and drum index in the metallurgical properties of the sinter show a gradual downward trend, and the low-temperature reduction pulverization index RDI+3.15 shows a gradual upward trend. The addition of ludwigite is conducive to the formation of calcium ferrite and promotes the activity of MgO. The addition of excessive ludwigite will lead to the formation of Mg2B2O5 and Ca3B2O6, Slag phase is formed. With the increase of the proportion of ludwigite, the melting range of the sinter is slightly widened, and the permeability is improved first and then reduced. Under this ore blending condition, ludwigite resources can be added and used in sintering batching, and the proportion shall not exceed 6%.","PeriodicalId":370509,"journal":{"name":"Metallurgical Research & Technology","volume":"38 17","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138597563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to prevent premature failure of high nickel ductile iron used for engine exhaust manifold due to thermal fatigue, the precipitation morphology, nucleation and growth mechanism of graphite particles in high-nickel ductile iron were systematically studied by optical and SEM microscopy and the growth kinetic equation of graphite particles was derived. The results show that the precipitation density and average size of graphite particles within the austenite grain of high-nickel ductile iron are 44.1 particles/mm2 and 2.2 µm, respectively, and the precipitation density and average size of graphite particles on the austenite grain boundaries are increased to 76.6 particles/mm2 and 17 µm, respectively. The main nucleation mechanism of graphite particles in high nickel austenitic ductile iron is grain boundary nucleation. The maximum nucleation rate temperature of graphite particles nucleated on grain boundary is 650–850 °C, the fastest precipitation temperature is close to 680 °C, and the time from the beginning to the end of the growth of graphite particles nucleated by grain boundary is about 3400 s. The average size of graphite particles precipitated by grain boundary nucleation can grow to grade 7 (15–30 µm) under the high temperature of 715–805 °C for a long time (over 3400 s), which is beneficial to the thermal fatigue property of high nickel ductile iron. The local temperature at manifold should not be higher than 800 °C under long times.
{"title":"Kinetics of precipitation for graphite particle in high nickel ductile iron","authors":"Yong Wan, Xiao Ling, Chuansheng Tang, Xue-jun Zhang, Yong-Ge Wen, D. Ma, Shan Gao, Q. Chen","doi":"10.1051/metal/2022103","DOIUrl":"https://doi.org/10.1051/metal/2022103","url":null,"abstract":"In order to prevent premature failure of high nickel ductile iron used for engine exhaust manifold due to thermal fatigue, the precipitation morphology, nucleation and growth mechanism of graphite particles in high-nickel ductile iron were systematically studied by optical and SEM microscopy and the growth kinetic equation of graphite particles was derived. The results show that the precipitation density and average size of graphite particles within the austenite grain of high-nickel ductile iron are 44.1 particles/mm2 and 2.2 µm, respectively, and the precipitation density and average size of graphite particles on the austenite grain boundaries are increased to 76.6 particles/mm2 and 17 µm, respectively. The main nucleation mechanism of graphite particles in high nickel austenitic ductile iron is grain boundary nucleation. The maximum nucleation rate temperature of graphite particles nucleated on grain boundary is 650–850 °C, the fastest precipitation temperature is close to 680 °C, and the time from the beginning to the end of the growth of graphite particles nucleated by grain boundary is about 3400 s. The average size of graphite particles precipitated by grain boundary nucleation can grow to grade 7 (15–30 µm) under the high temperature of 715–805 °C for a long time (over 3400 s), which is beneficial to the thermal fatigue property of high nickel ductile iron. The local temperature at manifold should not be higher than 800 °C under long times.","PeriodicalId":370509,"journal":{"name":"Metallurgical Research & Technology","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130708061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaole Cheng, D. Zhang, X. Wu, Guangshen Xu, H. Fu
In this paper, the effects of different quenching temperatures on the microstructure and properties of Fe–4.0C–35.0Cr–0.5Si (wt.%) low-silicon hypereutectic high-chromium cast iron (LS-HHCCI) was investigated. The effect of quenching temperature on the microstructure of LS-HHCCI was analyzed by optical microscope, scanning electron microscope, and X-ray diffractometer. After quenching at different temperatures, the hardness and wear resistance of LS-HHCCI were tested by Rockwell hardness tester, microhardness tester, and wear testing machine. The results show that the microstructure of as-cast LS-HHCCI is mainly composed of austenite matrix and M7C3 carbides. After quenching, the austenite matrix is transformed into martensite, and M23C6 type secondary carbides are precipitated in the matrix. As the quenching temperature increased from 950 °C to 1100 °C, the eutectic carbides first appeared as fine needles, and then they gather and grow up, showing elongated or lumpy. The hardness and abrasion resistance first increase and then decrease, it reached peak values of 67.2 HRC at the temperature of 1050 °C, while the wear resistance is the best.
{"title":"Effect of quenching temperature on microstructure and properties of low silicon hypereutectic high chromium cast iron","authors":"Xiaole Cheng, D. Zhang, X. Wu, Guangshen Xu, H. Fu","doi":"10.1051/metal/2022105","DOIUrl":"https://doi.org/10.1051/metal/2022105","url":null,"abstract":"In this paper, the effects of different quenching temperatures on the microstructure and properties of Fe–4.0C–35.0Cr–0.5Si (wt.%) low-silicon hypereutectic high-chromium cast iron (LS-HHCCI) was investigated. The effect of quenching temperature on the microstructure of LS-HHCCI was analyzed by optical microscope, scanning electron microscope, and X-ray diffractometer. After quenching at different temperatures, the hardness and wear resistance of LS-HHCCI were tested by Rockwell hardness tester, microhardness tester, and wear testing machine. The results show that the microstructure of as-cast LS-HHCCI is mainly composed of austenite matrix and M7C3 carbides. After quenching, the austenite matrix is transformed into martensite, and M23C6 type secondary carbides are precipitated in the matrix. As the quenching temperature increased from 950 °C to 1100 °C, the eutectic carbides first appeared as fine needles, and then they gather and grow up, showing elongated or lumpy. The hardness and abrasion resistance first increase and then decrease, it reached peak values of 67.2 HRC at the temperature of 1050 °C, while the wear resistance is the best.","PeriodicalId":370509,"journal":{"name":"Metallurgical Research & Technology","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120978564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yubao Liu, Lifeng Zhang, G. Cheng, Q. Ren, Wen Yang, Jujin Wang, Fengqin Liu
Laboratory experiments on the effect of lining refractory and high-basicity slag on non-metallic inclusions in a high carbon Al-killed steel were carried out. Alumina inclusions in the steel could hardly be affected by the Al2O3 refractory, however, would be transformed into MgO · Al2O3 when the MgO refractory was used. After the steel-slag-MgO lining-inclusion reaction, the high-basicity slag was saturated with MgO due to the dissolution of MgO from the refractory into the slag, meanwhile, original Al2O3 inclusions were transformed into MgO via MgO · Al2O3, regardless of the slag basicity. After the steel-slag-Al2O3 lining-inclusion reaction, the CaO/Al2O3 ratio of slag decreased significantly due to the dissolution of Al2O3 refractory into the slag, resulting in the slight increase of the magnesium content in steel and the transformation of Al2O3 inclusions into MgO · Al2O3. The reduction of the MgO in the lining refractory and top slag by the dissolved aluminum ([Al]) in molten steel occurred independently, and a higher CaO/Al2O3 ratio of slag would result in a higher activity of MgO, which was beneficial for the reduction of MgO. The CaO in the slag was hardly reduced by the [Al] in the molten steel, thus, it was proposed that CaO-Al2O3 type inclusions could hardly be generated from the steel-slag reaction during the production of high carbon Al-killed steels.
{"title":"Effect of lining refractory and high-basicity slag on non-metallic inclusions in a high carbon Al-killed steel","authors":"Yubao Liu, Lifeng Zhang, G. Cheng, Q. Ren, Wen Yang, Jujin Wang, Fengqin Liu","doi":"10.1051/metal/2022058","DOIUrl":"https://doi.org/10.1051/metal/2022058","url":null,"abstract":"Laboratory experiments on the effect of lining refractory and high-basicity slag on non-metallic inclusions in a high carbon Al-killed steel were carried out. Alumina inclusions in the steel could hardly be affected by the Al2O3 refractory, however, would be transformed into MgO · Al2O3 when the MgO refractory was used. After the steel-slag-MgO lining-inclusion reaction, the high-basicity slag was saturated with MgO due to the dissolution of MgO from the refractory into the slag, meanwhile, original Al2O3 inclusions were transformed into MgO via MgO · Al2O3, regardless of the slag basicity. After the steel-slag-Al2O3 lining-inclusion reaction, the CaO/Al2O3 ratio of slag decreased significantly due to the dissolution of Al2O3 refractory into the slag, resulting in the slight increase of the magnesium content in steel and the transformation of Al2O3 inclusions into MgO · Al2O3. The reduction of the MgO in the lining refractory and top slag by the dissolved aluminum ([Al]) in molten steel occurred independently, and a higher CaO/Al2O3 ratio of slag would result in a higher activity of MgO, which was beneficial for the reduction of MgO. The CaO in the slag was hardly reduced by the [Al] in the molten steel, thus, it was proposed that CaO-Al2O3 type inclusions could hardly be generated from the steel-slag reaction during the production of high carbon Al-killed steels.","PeriodicalId":370509,"journal":{"name":"Metallurgical Research & Technology","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134327526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study aims to investigate the effect of tundish level control on the change in element content and inclusion amount in molten steel during the low tundish-level steel grade transition. Based on multiphase flow, mass transfer, and discrete phase, a three-dimensional transient numerical simulation of the tundish was established in Ansys Fluent. The model uses moving mesh refinement technology to obtain clear steel and slag interface with a small number of meshes. The numerical simulation results were verified through industrial experiments and physical simulations. The results indicate that when the tundish is at a low level, strand 3 becomes a short-circuit flow, and the number of inclusions in strand 3 is approximately four times that in strand 1. If the old grade density is higher than that of the new grade, the unqualified length of the element content in the transition billet is 10.2 m shorter than that in the opposite order. When the filling speed of the tundish is three times the normal flow rate, the length of the transition billet with an unqualified number of inclusions is 7.1 m less than that when the filling speed is 2 times the normal flow rate. In addition, at the initial stage of the low tundish level steel grade transition, the minimum amount of inclusions in the transition billet can be reduced to 40% of the average amount of inclusions in the old grade; however, the maximum number of inclusions in the transition billet increase by a factor of 2.5 times the average number of inclusions in the new grade at the end stage of the low tundish-level steel grade transition. It can be observed that the inclusions in the initial stage of the low tundish-level steel grade transition have less effect on the quality of the old grades; however, they have a greater effect on the new grades in the final stage of the low tundish-level steel grade transition.
{"title":"Numerical modeling of grade mixing and inclusion entrapment in eight strand billet tundish","authors":"Sicheng Song, Yan-hui Sun, Hang-hang An","doi":"10.1051/metal/2023006","DOIUrl":"https://doi.org/10.1051/metal/2023006","url":null,"abstract":"This study aims to investigate the effect of tundish level control on the change in element content and inclusion amount in molten steel during the low tundish-level steel grade transition. Based on multiphase flow, mass transfer, and discrete phase, a three-dimensional transient numerical simulation of the tundish was established in Ansys Fluent. The model uses moving mesh refinement technology to obtain clear steel and slag interface with a small number of meshes. The numerical simulation results were verified through industrial experiments and physical simulations. The results indicate that when the tundish is at a low level, strand 3 becomes a short-circuit flow, and the number of inclusions in strand 3 is approximately four times that in strand 1. If the old grade density is higher than that of the new grade, the unqualified length of the element content in the transition billet is 10.2 m shorter than that in the opposite order. When the filling speed of the tundish is three times the normal flow rate, the length of the transition billet with an unqualified number of inclusions is 7.1 m less than that when the filling speed is 2 times the normal flow rate. In addition, at the initial stage of the low tundish level steel grade transition, the minimum amount of inclusions in the transition billet can be reduced to 40% of the average amount of inclusions in the old grade; however, the maximum number of inclusions in the transition billet increase by a factor of 2.5 times the average number of inclusions in the new grade at the end stage of the low tundish-level steel grade transition. It can be observed that the inclusions in the initial stage of the low tundish-level steel grade transition have less effect on the quality of the old grades; however, they have a greater effect on the new grades in the final stage of the low tundish-level steel grade transition.","PeriodicalId":370509,"journal":{"name":"Metallurgical Research & Technology","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115624249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Yuan, Xiaogang Wang, Guanghui Zhao, Peisheng Han
In the present study, a composite material of high chromium cast iron (HCCI) dispersed in low carbon steel (LCS) matrix was fabricated by the technology of accumulative roll-bonding (ARB). The microstructure characteristics were investigated using scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD). The tensile behavior and fracture characteristics of the composite were analyzed. The obtained microstructures illustrated that the HCCI was dispersed in the LCS after 3rd ARB cycle, forming a kind of composite material somewhat similar in its structure to a concrete. The coarse Cr-carbides of HCCI were broken and refined obviously through the hot-rolling deformation. However, some microcracks were formed on the fractured Cr-carbides of HCCI. The two materials were bonded by mechanical and metallurgical bonding, and a diffusion band with a thickness of ∼10 µm was formed on the interface. Compared with the as-cast HCCI plate, the composite material after 3rd ARB cycle possessed good comprehensive tensile properties. The fracture characteristics of the composite material included the multiple tunnel fracture of HCCI and the shear fracture of LCS.
{"title":"Microstructure and tensile behavior of high-chromium cast iron/low-carbon steel composite fabricated by accumulative roll-bonding","authors":"G. Yuan, Xiaogang Wang, Guanghui Zhao, Peisheng Han","doi":"10.1051/metal/2022085","DOIUrl":"https://doi.org/10.1051/metal/2022085","url":null,"abstract":"In the present study, a composite material of high chromium cast iron (HCCI) dispersed in low carbon steel (LCS) matrix was fabricated by the technology of accumulative roll-bonding (ARB). The microstructure characteristics were investigated using scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD). The tensile behavior and fracture characteristics of the composite were analyzed. The obtained microstructures illustrated that the HCCI was dispersed in the LCS after 3rd ARB cycle, forming a kind of composite material somewhat similar in its structure to a concrete. The coarse Cr-carbides of HCCI were broken and refined obviously through the hot-rolling deformation. However, some microcracks were formed on the fractured Cr-carbides of HCCI. The two materials were bonded by mechanical and metallurgical bonding, and a diffusion band with a thickness of ∼10 µm was formed on the interface. Compared with the as-cast HCCI plate, the composite material after 3rd ARB cycle possessed good comprehensive tensile properties. The fracture characteristics of the composite material included the multiple tunnel fracture of HCCI and the shear fracture of LCS.","PeriodicalId":370509,"journal":{"name":"Metallurgical Research & Technology","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121071042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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