Chunhui Jin, Honglin Zhou, L. Yuan, Bei Li, Zhang Kewei, C. Huiqin, Zhao Jinhua
The influence of aging temperature on microstructure and mechanical properties of Cr15Ni5 precipitation hardening stainless steel (15-5 PH stainless steel) were investigated at aging temperature range of 440–610 °C. The tensile properties at ambient temperature of the 15-5 PH stainless steel processed by different aging temperatures were tested, and the microstructural features were further analyzed utilizing optical microscope (OM), transmission electron microscope (TEM), electron backscatter diffraction (EBSD) as well as X-ray diffraction (XRD), respectively. Results indicated the strength of the 15-5 PH stainless steel was firstly decreased with increment of aging temperature from 440 to 540 °C, and then increased with the increment of aging temperature from 540 to 610 °C. The strength and ductility were well matched at aging temperature 470 °C, and the yield strength, tensile strength as well as elongation were determined to be 1170 MPa, 1240 MPa and 24%, respectively. The microstructures concerning to different aging temperatures were overall confirmed to be lath martensite. The strengthening mechanisms induced by dislocation density and the second phase precipitation of Cu-enriched metallic compound under different aging temperatures were determined to be the predominant strengthening mechanisms controlling the variation trend of mechanical properties corresponding to different aging temperatures with respect to 15-5 PH stainless steel.
{"title":"Microstructure and mechanical properties of 15-5 PH stainless steel under different aging temperature","authors":"Chunhui Jin, Honglin Zhou, L. Yuan, Bei Li, Zhang Kewei, C. Huiqin, Zhao Jinhua","doi":"10.1051/metal/2021078","DOIUrl":"https://doi.org/10.1051/metal/2021078","url":null,"abstract":"The influence of aging temperature on microstructure and mechanical properties of Cr15Ni5 precipitation hardening stainless steel (15-5 PH stainless steel) were investigated at aging temperature range of 440–610 °C. The tensile properties at ambient temperature of the 15-5 PH stainless steel processed by different aging temperatures were tested, and the microstructural features were further analyzed utilizing optical microscope (OM), transmission electron microscope (TEM), electron backscatter diffraction (EBSD) as well as X-ray diffraction (XRD), respectively. Results indicated the strength of the 15-5 PH stainless steel was firstly decreased with increment of aging temperature from 440 to 540 °C, and then increased with the increment of aging temperature from 540 to 610 °C. The strength and ductility were well matched at aging temperature 470 °C, and the yield strength, tensile strength as well as elongation were determined to be 1170 MPa, 1240 MPa and 24%, respectively. The microstructures concerning to different aging temperatures were overall confirmed to be lath martensite. The strengthening mechanisms induced by dislocation density and the second phase precipitation of Cu-enriched metallic compound under different aging temperatures were determined to be the predominant strengthening mechanisms controlling the variation trend of mechanical properties corresponding to different aging temperatures with respect to 15-5 PH stainless steel.","PeriodicalId":18527,"journal":{"name":"Metallurgical Research & Technology","volume":"42 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72494088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effects of MgO on carbothermal reduction of Fe2TiO4 had been researched including the thermodynamic calculation in this paper. And, based on XRD and SEM-EDS, the effect mechanism of MgO on the direct reduction of Fe2TiO4 had been deeply dissected, systematically. The results showed that magnesium titanium phases including MgTi2O5, MgTiO3 and Mg2TiO4 were formatted after MgO added into Fe2TiO4, which was main reason to affect the reduction of Fe2TiO4. When the MgO content in Fe2TiO4 did not exceed 2%, there was the promoting effect on the reduction of Fe2TiO4. With the increase of MgO content from 2% to 8%, the magnesium titanium phases transformed from MgTi2O5, and through MgTiO3 to Mg2TiO4. The inhibition function appeared, and can be weaken in the high reduction temperature. When reduction temperature reaches to 1300 °C, the metallization rate of F-M-8 (the reduction sample of 8% MgO) can reach 80.62% from 56.43% at 1200 °C. However, the aggregation degree of iron particles became worse when MgO was added to the sample.
{"title":"Effects and mechanism of MgO on carbothermal reduction of Fe2TiO4","authors":"Yunfei Chen, Xiangdong Xing","doi":"10.1051/metal/2021059","DOIUrl":"https://doi.org/10.1051/metal/2021059","url":null,"abstract":"The effects of MgO on carbothermal reduction of Fe2TiO4 had been researched including the thermodynamic calculation in this paper. And, based on XRD and SEM-EDS, the effect mechanism of MgO on the direct reduction of Fe2TiO4 had been deeply dissected, systematically. The results showed that magnesium titanium phases including MgTi2O5, MgTiO3 and Mg2TiO4 were formatted after MgO added into Fe2TiO4, which was main reason to affect the reduction of Fe2TiO4. When the MgO content in Fe2TiO4 did not exceed 2%, there was the promoting effect on the reduction of Fe2TiO4. With the increase of MgO content from 2% to 8%, the magnesium titanium phases transformed from MgTi2O5, and through MgTiO3 to Mg2TiO4. The inhibition function appeared, and can be weaken in the high reduction temperature. When reduction temperature reaches to 1300 °C, the metallization rate of F-M-8 (the reduction sample of 8% MgO) can reach 80.62% from 56.43% at 1200 °C. However, the aggregation degree of iron particles became worse when MgO was added to the sample.","PeriodicalId":18527,"journal":{"name":"Metallurgical Research & Technology","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84121170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiao-qian Pan, Jian Yang, Yinhui Zhang, Joo-Chang Park, H. Ono
The submicrometre and nanometre particle characteristics, soluble element contents, and austenite grain growth behaviors in heat-affected zone of offshore engineering steels with 0.0002 (2Mg) and 0.0042 (42Mg) wt.% Mg during the simulated welding process were studied. With increasing the Mg content in steel from 0.0002 to 0.0042 wt.%, the submicron particles are decreased in number and size with their compositions evolved from TiN to TiN + MgO capped with Mo carbides, and the number density of small-sized nanoparticles increases and large-sized nanoparticles decreases. When the temperature is below 1250 °C, the grain growth rate of two steels is not much different due to the larger Mo solute drag effect in 2Mg and larger pinning force in 42Mg. When the temperature is 1250–1300 °C, the small-sized nanoparticles in 42Mg is more than that in 2Mg, resulting in the larger pinning force and smaller grain growth rate in 42Mg. When heated to 1300–1350 °C and soaked at 1350 °C for 300 s, since large quantities of particles smaller than the critical size (dcr) are dissolved, the grain growth rate in 2Mg is smaller than that in 42Mg due to the greater amount of the effective pinning particles and larger pinning force in 2Mg.
{"title":"Influence of the Mg content on the austenite grain growth in heat-affected zone of offshore engineering steels considering TiN particle pinning and Mo solute drag effects","authors":"Xiao-qian Pan, Jian Yang, Yinhui Zhang, Joo-Chang Park, H. Ono","doi":"10.1051/metal/2021052","DOIUrl":"https://doi.org/10.1051/metal/2021052","url":null,"abstract":"The submicrometre and nanometre particle characteristics, soluble element contents, and austenite grain growth behaviors in heat-affected zone of offshore engineering steels with 0.0002 (2Mg) and 0.0042 (42Mg) wt.% Mg during the simulated welding process were studied. With increasing the Mg content in steel from 0.0002 to 0.0042 wt.%, the submicron particles are decreased in number and size with their compositions evolved from TiN to TiN + MgO capped with Mo carbides, and the number density of small-sized nanoparticles increases and large-sized nanoparticles decreases. When the temperature is below 1250 °C, the grain growth rate of two steels is not much different due to the larger Mo solute drag effect in 2Mg and larger pinning force in 42Mg. When the temperature is 1250–1300 °C, the small-sized nanoparticles in 42Mg is more than that in 2Mg, resulting in the larger pinning force and smaller grain growth rate in 42Mg. When heated to 1300–1350 °C and soaked at 1350 °C for 300 s, since large quantities of particles smaller than the critical size (dcr) are dissolved, the grain growth rate in 2Mg is smaller than that in 42Mg due to the greater amount of the effective pinning particles and larger pinning force in 2Mg.","PeriodicalId":18527,"journal":{"name":"Metallurgical Research & Technology","volume":"9 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84238078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tingsong Yang, Jiayang Liu, X. Ren, Yingwei Wang, F. Du
Roll profile electromagnetic control technology (RPECT) is a new strip flatness control technology. As the control element, electromagnetic sticks have a great effect on the control ability of RPECT. To improve control ability and extend service life, effective control ratio of electromagnetic stick is presented in this paper. The ratio is designed based on the structure character of electromagnetic stick, and can be used to evaluate the key parameter of electromagnetic stick. Based on the coupled FEM, the heat flux density of the roll inner hole and the temperature distribution of electromagnetic stick are analyzed for different effective control ratios; the average contact pressure between electromagnetic stick and electromagnetic control roll is studied to evaluate the change of force roll profile; the state of roll profile and the stress state of the roll are researched to analyze the comprehensive control ability. Through the verification on the roll profile electromagnetic control experimental platform, the reasonable selection range of effective control ratio, which can be used to expand the roll profile axial affected area, is from 0.5 to 0.583. In order to increase the roll crown, the selection of ηd needs to consider the current density and the optimal selection range of effective control ratio.
{"title":"Research on roll profile electromagnetic control ability in optimal electromagnetic stick parameter","authors":"Tingsong Yang, Jiayang Liu, X. Ren, Yingwei Wang, F. Du","doi":"10.1051/METAL/2021031","DOIUrl":"https://doi.org/10.1051/METAL/2021031","url":null,"abstract":"Roll profile electromagnetic control technology (RPECT) is a new strip flatness control technology. As the control element, electromagnetic sticks have a great effect on the control ability of RPECT. To improve control ability and extend service life, effective control ratio of electromagnetic stick is presented in this paper. The ratio is designed based on the structure character of electromagnetic stick, and can be used to evaluate the key parameter of electromagnetic stick. Based on the coupled FEM, the heat flux density of the roll inner hole and the temperature distribution of electromagnetic stick are analyzed for different effective control ratios; the average contact pressure between electromagnetic stick and electromagnetic control roll is studied to evaluate the change of force roll profile; the state of roll profile and the stress state of the roll are researched to analyze the comprehensive control ability. Through the verification on the roll profile electromagnetic control experimental platform, the reasonable selection range of effective control ratio, which can be used to expand the roll profile axial affected area, is from 0.5 to 0.583. In order to increase the roll crown, the selection of ηd needs to consider the current density and the optimal selection range of effective control ratio.","PeriodicalId":18527,"journal":{"name":"Metallurgical Research & Technology","volume":"25 6 1","pages":"305"},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82694448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Colmonoy 6 alloy has been regarded as an efficient overlay material for various grades of substrate materials. The PTAW process has been emerged as a very useful process to deposit such materials effectively. Torch oscillation may become an efficient PTAW parameter to achieve a desired microstructure due to its significant advantage over liner torch movement due to a faster cooling of the weld pool. Proposed work aims to analyse the influence of torch oscillation on the microstructure of Colmonoy 6 overlay surface on SS304 substrate. The structure of the surface deposited with PTAW torch oscillation shows increase in the Cr concentration in δ-Cr7C3, θ-(Cr, Fe)7C3 and μ-Cr23C7 phases upon characterization by SEM with EDS and XRD. This decreases the solidification temperature of Ni-based soft matrix which provides a higher hardness of the coating. These outcomes can also come handy for other grades of materials to control their metallurgical characteristics effectively.
{"title":"Influence of torch oscillation on the microstructure of Colmonoy 6 overlay deposition on SS304 substrate with PTA welding process","authors":"V. Kalyankar, Avishkar Bhoskar","doi":"10.1051/metal/2021045","DOIUrl":"https://doi.org/10.1051/metal/2021045","url":null,"abstract":"Colmonoy 6 alloy has been regarded as an efficient overlay material for various grades of substrate materials. The PTAW process has been emerged as a very useful process to deposit such materials effectively. Torch oscillation may become an efficient PTAW parameter to achieve a desired microstructure due to its significant advantage over liner torch movement due to a faster cooling of the weld pool. Proposed work aims to analyse the influence of torch oscillation on the microstructure of Colmonoy 6 overlay surface on SS304 substrate. The structure of the surface deposited with PTAW torch oscillation shows increase in the Cr concentration in δ-Cr7C3, θ-(Cr, Fe)7C3 and μ-Cr23C7 phases upon characterization by SEM with EDS and XRD. This decreases the solidification temperature of Ni-based soft matrix which provides a higher hardness of the coating. These outcomes can also come handy for other grades of materials to control their metallurgical characteristics effectively.","PeriodicalId":18527,"journal":{"name":"Metallurgical Research & Technology","volume":"19 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82722769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The surface tension of mold flux is an important parameter for controlling the quality of continuous billet, affected deeply by the compositions of mold flux and temperature, andclosed related with the structure of mold flux. In the present study, the effect of CaF2 and temperature on the surface tension of CaO-SiO2 -Al2 O3 -Na2 O-CaF2 mold flux melts is investigated by the pulling cylinder method; furthermore, the structure of melts is determined by FT-IR spectroscopy to analyze the change mechanism of surface tension. The results indicate that the variation of surface tension is in accord with that of structure of melts. The surface tension of melt decreases with the increase of CaF2 mass fraction, and this tendency becomes more apparent at higher temperature. The FT-IR spectra show thatboth the amount of Ob andthe degree of structural polymerization of melts decrease as the CaF2 content increases. This is because the Si-Ob bonds in the [SiO4 ]-tetrahedrons are broken by F− and transformed into Si-F bonds, and the silicon-oxygen anions with more complex structure were depolymerized into silicon-oxygen anions containing fluorine with simpler structure, resulting in an increase of Si-F saturated bonds on the melt surface, and thusreducing the surface tension of melts.
{"title":"Effect of fluorine on surface tension of CaO-SiO2-Al2O3-Na2O-CaF2 mold flux","authors":"Q. Gao, Longhu Cao","doi":"10.1051/METAL/2021040","DOIUrl":"https://doi.org/10.1051/METAL/2021040","url":null,"abstract":"The surface tension of mold flux is an important parameter for controlling the quality of continuous billet, affected deeply by the compositions of mold flux and temperature, andclosed related with the structure of mold flux. In the present study, the effect of CaF2 and temperature on the surface tension of CaO-SiO2 -Al2 O3 -Na2 O-CaF2 mold flux melts is investigated by the pulling cylinder method; furthermore, the structure of melts is determined by FT-IR spectroscopy to analyze the change mechanism of surface tension. The results indicate that the variation of surface tension is in accord with that of structure of melts. The surface tension of melt decreases with the increase of CaF2 mass fraction, and this tendency becomes more apparent at higher temperature. The FT-IR spectra show thatboth the amount of Ob andthe degree of structural polymerization of melts decrease as the CaF2 content increases. This is because the Si-Ob bonds in the [SiO4 ]-tetrahedrons are broken by F− and transformed into Si-F bonds, and the silicon-oxygen anions with more complex structure were depolymerized into silicon-oxygen anions containing fluorine with simpler structure, resulting in an increase of Si-F saturated bonds on the melt surface, and thusreducing the surface tension of melts.","PeriodicalId":18527,"journal":{"name":"Metallurgical Research & Technology","volume":"7 1","pages":"316"},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86991025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fei Li, Liwen Zhang, Chi Zhang, Qing Yang, Chaoqun Li, P. Mao
The static recrystallization (SRX) behavior of a low carbon Nb–V–Ti microalloyed steel X70 was investigated by two-pass hot compression tests. The compression tests were carried out at deformation temperatures of 1000–1150 °C, strain rates of 0.01–5 s−1 , pre-strains of 0.1–0.2 and interval times of 1–50 s. The effects of deformation parameters on SRX behavior were analyzed. The experimental results showed that deformation temperature, pre-strain and strain rate had significant influence on SRX fraction, while initial grain size had a smaller impact. The effects of deformation parameters on SRX microstructure were discussed, and the microstructure evolution process was analyzed. Higher deformation temperature, strain rate and pre-strain lead to larger SRX fraction. The kinetics and recrystallized grain size models for SRX of X70 pipeline steel were developed. Comparison between the predicted results and the experimental ones indicated that the established equations could give a reasonable description for SRX behavior of X70 pipeline steel.
{"title":"Experimental investigation on static recrystallization behavior of a low carbon Nb–V–Ti microalloyed steel","authors":"Fei Li, Liwen Zhang, Chi Zhang, Qing Yang, Chaoqun Li, P. Mao","doi":"10.1051/METAL/2021003","DOIUrl":"https://doi.org/10.1051/METAL/2021003","url":null,"abstract":"The static recrystallization (SRX) behavior of a low carbon Nb–V–Ti microalloyed steel X70 was investigated by two-pass hot compression tests. The compression tests were carried out at deformation temperatures of 1000–1150 °C, strain rates of 0.01–5 s−1 , pre-strains of 0.1–0.2 and interval times of 1–50 s. The effects of deformation parameters on SRX behavior were analyzed. The experimental results showed that deformation temperature, pre-strain and strain rate had significant influence on SRX fraction, while initial grain size had a smaller impact. The effects of deformation parameters on SRX microstructure were discussed, and the microstructure evolution process was analyzed. Higher deformation temperature, strain rate and pre-strain lead to larger SRX fraction. The kinetics and recrystallized grain size models for SRX of X70 pipeline steel were developed. Comparison between the predicted results and the experimental ones indicated that the established equations could give a reasonable description for SRX behavior of X70 pipeline steel.","PeriodicalId":18527,"journal":{"name":"Metallurgical Research & Technology","volume":"70 1","pages":"202"},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79271136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Q. Meng, G. Yu, Xue-ying Huang, Hong-Lei Sun, Jun-min Zhao
The straightness is a critical quality parameter of metal profiles, and straightening is a necessary process in metal profile production. Due to the limitations of the existing straightening methods, the straightening process by reciprocating bending for metal profiles is proposed. The curvature is unified by multiple reciprocating bending, and then the straightening is completed by reverse bending. The process has the advantages of high straightening efficiency, flexibility, and wide straightening range. In order to verify the feasibility of the process, numerical simulation and physical experiment are carried out with the rectangular section profile with “C” shape and “S” shape. The results show the profiles of different shapes are unified into arcs of the same size after multiple reciprocating bending. In addition, the smaller the elastic area ratio (ratio of elastic deformation to overall deformation) is, the better the effect of unification curvature is. The residual deflection is basically the same after straightening, and straightness is within 0.1%.
{"title":"Study on a straightening process by reciprocating bending for metal profiles","authors":"Q. Meng, G. Yu, Xue-ying Huang, Hong-Lei Sun, Jun-min Zhao","doi":"10.1051/metal/2021081","DOIUrl":"https://doi.org/10.1051/metal/2021081","url":null,"abstract":"The straightness is a critical quality parameter of metal profiles, and straightening is a necessary process in metal profile production. Due to the limitations of the existing straightening methods, the straightening process by reciprocating bending for metal profiles is proposed. The curvature is unified by multiple reciprocating bending, and then the straightening is completed by reverse bending. The process has the advantages of high straightening efficiency, flexibility, and wide straightening range. In order to verify the feasibility of the process, numerical simulation and physical experiment are carried out with the rectangular section profile with “C” shape and “S” shape. The results show the profiles of different shapes are unified into arcs of the same size after multiple reciprocating bending. In addition, the smaller the elastic area ratio (ratio of elastic deformation to overall deformation) is, the better the effect of unification curvature is. The residual deflection is basically the same after straightening, and straightness is within 0.1%.","PeriodicalId":18527,"journal":{"name":"Metallurgical Research & Technology","volume":"357 6","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72441363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, isothermal and hot corrosion in molten 75 mass% Na2 SO4 +25 mass% NaCl at 900 °C was carried out on an W richen Co-based directionally solidified Co-27.53Cr-9.85W-10.29Ni-0.75Al superalloy. For comparison, K38G with composition of 16.34Cr-4Al-1.77Mo-3.81Ti-2.66W-8.38Co were also conducted under same condition. Isothermal oxidation indicates that Co-based superalloy forms a Co-oxide dispersion chromia scale. However, K38G forms a purer chromia scale due to higher weight percentage ratio of Cr to Al. Under molten Na2 SO4 -NaCl salts, the defects in Ni/Co oxide dispersion chromia layer make it feasible that the molten salt can penetrates along grain boundaries into the internal interface to form internal sulfides, which causes the spallation of scales and significantly decreases its hot corrosion resistance.
{"title":"Oxidation and hot corrosion behavior of a directionally solidified W richen cobalt-based superalloy","authors":"Yue Zhou, C. Mo, Hong Wang","doi":"10.1051/METAL/2021033","DOIUrl":"https://doi.org/10.1051/METAL/2021033","url":null,"abstract":"In this study, isothermal and hot corrosion in molten 75 mass% Na2 SO4 +25 mass% NaCl at 900 °C was carried out on an W richen Co-based directionally solidified Co-27.53Cr-9.85W-10.29Ni-0.75Al superalloy. For comparison, K38G with composition of 16.34Cr-4Al-1.77Mo-3.81Ti-2.66W-8.38Co were also conducted under same condition. Isothermal oxidation indicates that Co-based superalloy forms a Co-oxide dispersion chromia scale. However, K38G forms a purer chromia scale due to higher weight percentage ratio of Cr to Al. Under molten Na2 SO4 -NaCl salts, the defects in Ni/Co oxide dispersion chromia layer make it feasible that the molten salt can penetrates along grain boundaries into the internal interface to form internal sulfides, which causes the spallation of scales and significantly decreases its hot corrosion resistance.","PeriodicalId":18527,"journal":{"name":"Metallurgical Research & Technology","volume":"13 1","pages":"313"},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77157369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaoyong Gao, Lin Zhang, Lifeng Zhang, Q. Ren, X. Qu
Rare earth metal transfer from slag to alloy and inclusion was investigated by slag-metal reaction method. Rare earth oxide (CeO2) employed in the refining slags was used a sample case. The results show that direct application of rare earth oxide in the slag is an alternative to traditional way which uses pure rare earth metal or rare-earth ferrous alloy to add rare earth in an alloy. Slag-metal reaction method proves to be an effective way to improve the rare earth transfer from slags to alloys with high content of Al. The content of Ce in the alloy increased with the increasing CeO2/Al2O3 mass ratio of the slag. As the Ce concentration of molten alloy increased from 0 to 105 ppm, the Al2O3 type inclusion was changed into cerium oxide, cerium sulfide and cerium oxy-sulfide inclusions. In addition, the morphology of inclusions was transformed from irregular to near spherical. Finally, the mechanism was discussed by thermodynamic analysis.
{"title":"Transfer of rare earth to alloy and inclusion during slag-metal reaction","authors":"Xiaoyong Gao, Lin Zhang, Lifeng Zhang, Q. Ren, X. Qu","doi":"10.1051/metal/2021057","DOIUrl":"https://doi.org/10.1051/metal/2021057","url":null,"abstract":"Rare earth metal transfer from slag to alloy and inclusion was investigated by slag-metal reaction method. Rare earth oxide (CeO2) employed in the refining slags was used a sample case. The results show that direct application of rare earth oxide in the slag is an alternative to traditional way which uses pure rare earth metal or rare-earth ferrous alloy to add rare earth in an alloy. Slag-metal reaction method proves to be an effective way to improve the rare earth transfer from slags to alloys with high content of Al. The content of Ce in the alloy increased with the increasing CeO2/Al2O3 mass ratio of the slag. As the Ce concentration of molten alloy increased from 0 to 105 ppm, the Al2O3 type inclusion was changed into cerium oxide, cerium sulfide and cerium oxy-sulfide inclusions. In addition, the morphology of inclusions was transformed from irregular to near spherical. Finally, the mechanism was discussed by thermodynamic analysis.","PeriodicalId":18527,"journal":{"name":"Metallurgical Research & Technology","volume":"63 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82606350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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