Chao Li, Xingye Ma, Jinfeng Bai, Gang Wang, Yang Liu, Yuesi Sui, Xiangyun Zhong, Guozhong Xu, Shiyong Wu
The effects of two cokes with different reactivity on the lump ore's metallurgical properties and coke's solution loss are investigated under the high‐temperature load reduction. The work used an improved test device for softening‐melting and dropping characteristics of iron ores in both CO2 and CO2H2O atmospheres. The deterioration behavior of highly reactive cokes is expounded under hydrogen‐rich conditions. High‐reactivity cokes under hydrogen‐rich conditions are more favorable for enhancing the breathability of charge and the penetration of the coke layer. However, it increased the thickness of the softening zone. High‐reactivity cokes had obvious internal and external reaction gradients. The solution loss reaction mostly occurred on the surface, with selectivity. The longitudinal stacking height, layer number, and order degree in the carbon structure decreases after the reaction. The carbon‐structure difference weakens between the shell and core. The enhancement of coke's reactivity, however, results in the significant loss of coke powders on its surface. Unreduced FeO and refractory Fe2SiO4 are more likely to appear in the droplets, which is not conducive to the reduction of Fe and the generation of slag crust in the furnace. The difficulty in separating lump ores and cokes is aggravated, and more iron‐containing charge remain in the furnace.
研究了在高温减载条件下，两种不同反应活性的焦炭对块状矿石冶金特性和焦炭溶解损失的影响。这项工作使用了一种改进的试验装置，用于测试铁矿石在 CO2 和 CO2H2O 两种气氛下的软化-熔化和熔滴特性。阐述了高活性焦炭在富氢条件下的劣化行为。富氢条件下的高活性焦炭更有利于提高炉料的透气性和焦炭层的渗透性。但是，它增加了软化区的厚度。高活性焦炭具有明显的内外反应梯度。溶液流失反应主要发生在表面，具有选择性。反应后，碳结构的纵向堆积高度、层数和有序度降低。外壳和内核之间的碳结构差异减弱。然而，焦炭反应活性的增强导致其表面焦炭粉末的大量流失。液滴中更容易出现未还原的 FeO 和难熔的 Fe2SiO4，不利于铁的还原和炉内渣壳的生成。块矿和焦炭分离的难度加大，炉内残留的含铁炉料增多。
{"title":"Application of High‐ and Low‐Reactivity Cokes in Hydrogen‐Rich Blast Furnaces","authors":"Chao Li, Xingye Ma, Jinfeng Bai, Gang Wang, Yang Liu, Yuesi Sui, Xiangyun Zhong, Guozhong Xu, Shiyong Wu","doi":"10.1002/srin.202400445","DOIUrl":"https://doi.org/10.1002/srin.202400445","url":null,"abstract":"The effects of two cokes with different reactivity on the lump ore's metallurgical properties and coke's solution loss are investigated under the high‐temperature load reduction. The work used an improved test device for softening‐melting and dropping characteristics of iron ores in both CO<jats:sub>2</jats:sub> and CO<jats:sub>2</jats:sub>H<jats:sub>2</jats:sub>O atmospheres. The deterioration behavior of highly reactive cokes is expounded under hydrogen‐rich conditions. High‐reactivity cokes under hydrogen‐rich conditions are more favorable for enhancing the breathability of charge and the penetration of the coke layer. However, it increased the thickness of the softening zone. High‐reactivity cokes had obvious internal and external reaction gradients. The solution loss reaction mostly occurred on the surface, with selectivity. The longitudinal stacking height, layer number, and order degree in the carbon structure decreases after the reaction. The carbon‐structure difference weakens between the shell and core. The enhancement of coke's reactivity, however, results in the significant loss of coke powders on its surface. Unreduced FeO and refractory Fe<jats:sub>2</jats:sub>SiO<jats:sub>4</jats:sub> are more likely to appear in the droplets, which is not conducive to the reduction of Fe and the generation of slag crust in the furnace. The difficulty in separating lump ores and cokes is aggravated, and more iron‐containing charge remain in the furnace.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In practical applications, intermetallic compounds like Laves phase and metal carbides adversely affect the performance of nickel‐based superalloys. Using a high‐temperature confocal laser scanning microscope, the solidification process of as‐cast GH3625 alloy containing Mg at different cooling rates (−20, −35, and −50 °C min−1) is studied. Fitting curves of the volume fraction of the solid phase with solidification temperature before and after Mg treatment are obtained. Trends of solid phase transformation rates with solidification temperature are determined. Differential scanning calorimetry is employed to analyze and statistically evaluate the melting temperature range and enthalpy of each phase during the melting process. Experimental results demonstrate that Mg treatment significantly accelerates the alloy solidification at the cooling rates of −20 and −35 °C min−1, while reducing the area of residual liquid phase at the same solidification temperature, disrupting the Laves/NbC eutectic relationship, and regularizing NbC morphology, transitioning its distribution from aggregation to dispersion. After Mg treatment, the precipitation of the Laves phase is significantly reduced. As a result, the influence mechanism of Mg treatment on the phase transformation and microstructure of GH3625 is clarified based on homogeneous nucleation theory.
在实际应用中，拉维斯相和金属碳化物等金属间化合物会对镍基超级合金的性能产生不利影响。利用高温共焦激光扫描显微镜，研究了含镁铸件 GH3625 合金在不同冷却速率（-20、-35 和 -50 °C min-1）下的凝固过程。得到了镁处理前后固相体积分数随凝固温度变化的拟合曲线。确定了固相转化率随凝固温度的变化趋势。采用差示扫描量热法对熔化过程中各相的熔化温度范围和焓进行了分析和统计评估。实验结果表明，在冷却速度为 -20 和 -35 °C min-1 时，镁处理显著加速了合金凝固，同时减少了相同凝固温度下的残余液相面积，破坏了 Laves/NbC 共晶关系，并使 NbC 形态规则化，使其分布从聚集过渡到分散。镁处理后，Laves 相的析出明显减少。因此，基于均相成核理论，阐明了镁处理对 GH3625 相变和微观结构的影响机制。
{"title":"In Situ Observation of Microstructure and Precipitate Phase Transformation during the Solidification of Mg‐Containing GH3625 Alloy at Different Cooling Rates","authors":"Yu Zhang, Wei Gong, Pengfei Wang, Xingtong Li","doi":"10.1002/srin.202400301","DOIUrl":"https://doi.org/10.1002/srin.202400301","url":null,"abstract":"In practical applications, intermetallic compounds like Laves phase and metal carbides adversely affect the performance of nickel‐based superalloys. Using a high‐temperature confocal laser scanning microscope, the solidification process of as‐cast GH3625 alloy containing Mg at different cooling rates (−20, −35, and −50 °C min<jats:sup>−1</jats:sup>) is studied. Fitting curves of the volume fraction of the solid phase with solidification temperature before and after Mg treatment are obtained. Trends of solid phase transformation rates with solidification temperature are determined. Differential scanning calorimetry is employed to analyze and statistically evaluate the melting temperature range and enthalpy of each phase during the melting process. Experimental results demonstrate that Mg treatment significantly accelerates the alloy solidification at the cooling rates of −20 and −35 °C min<jats:sup>−1</jats:sup>, while reducing the area of residual liquid phase at the same solidification temperature, disrupting the Laves/NbC eutectic relationship, and regularizing NbC morphology, transitioning its distribution from aggregation to dispersion. After Mg treatment, the precipitation of the Laves phase is significantly reduced. As a result, the influence mechanism of Mg treatment on the phase transformation and microstructure of GH3625 is clarified based on homogeneous nucleation theory.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anastasiia Sherstneva, Caroline Quitzke, Matheus R. Bellé, Marco Wendler, Olena Volkova
To obtain a successful product during additive manufacturing, the powder as a raw material must have the high quality. The purpose of this work is to investigate CrMnNi steel powders obtained by inert gas atomization with nickel content: 3, 6, and 9 wt% and to identify dependencies between the powder size and morphology, solidification structure, and change in chemical composition and thermophysical properties. Particle size distribution is measured by a laser scattering analyzer: d50 value are 82.02, 69.32, and 75.54 μm for powders with 3, 6, and 9 wt%, respectively. Surface tension (ST) measurements are made by maximum bubble pressure method: for steels with 3, 6, and 9 wt% at temperature 1500 °C, ST is 1.01, 1.07, and 1.15 mN m−1, respectively. It is found that the change in particle size affects the chemical composition, the content of the ferromagnetic phase and secondary dendritic arm‐spacing. Changes in the content of elements such as S, O, N, and Mn are determined, depending on the diameter of the particles. The influence of changes in content of S, O, and N on the thermophysical properties such as ST is investigated.
{"title":"Characterization of CrMnNi Steel Powders Obtained via Gas Atomization","authors":"Anastasiia Sherstneva, Caroline Quitzke, Matheus R. Bellé, Marco Wendler, Olena Volkova","doi":"10.1002/srin.202400267","DOIUrl":"https://doi.org/10.1002/srin.202400267","url":null,"abstract":"To obtain a successful product during additive manufacturing, the powder as a raw material must have the high quality. The purpose of this work is to investigate CrMnNi steel powders obtained by inert gas atomization with nickel content: 3, 6, and 9 wt% and to identify dependencies between the powder size and morphology, solidification structure, and change in chemical composition and thermophysical properties. Particle size distribution is measured by a laser scattering analyzer: d<jats:sub>50</jats:sub> value are 82.02, 69.32, and 75.54 μm for powders with 3, 6, and 9 wt%, respectively. Surface tension (ST) measurements are made by maximum bubble pressure method: for steels with 3, 6, and 9 wt% at temperature 1500 °C, ST is 1.01, 1.07, and 1.15 mN m<jats:sup>−1</jats:sup>, respectively. It is found that the change in particle size affects the chemical composition, the content of the ferromagnetic phase and secondary dendritic arm‐spacing. Changes in the content of elements such as S, O, N, and Mn are determined, depending on the diameter of the particles. The influence of changes in content of S, O, and N on the thermophysical properties such as ST is investigated.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Accumulative roll bonding (ARB) is a repeated cladding process in which two or more sheets of material are joined together by rolling at temperatures below recrystallization. The present review is focused on ARB of high‐alloy steels, which, among other laminated metal composites (LMCs), deliver the highest mechanical properties. After a brief description of high‐strength steels, history, and state of the art of LMCs, the principal roll bonding mechanism is explained. Further, the methodology of ARB of steels and variable parameters (stacking, temperature, etc.) are discussed. Known examples of steel–steel laminates are summarized with respect to their rolling temperature and mechanical properties. Further, the main toughening mechanisms of steel‐based LMCs are listed. The most promising candidates of high‐alloy steel laminates are presented in more detail. The important deformation mechanisms of twinning‐ and transformation‐induced plasticity (TWIP and TRIP) high‐alloy steels are explained. Microstructural changes and layer bonding as well as mechanical properties and damage behavior of two‐ and four‐layered TRIP/TWIP steel laminates are illustrated, including some specific phenomena, such as deformation lenses. Finally, by summarizing the analyzed data on steel laminates, conclusions and outlook are formulated.
{"title":"Steel–Steel Laminates Manufactured via Accumulative Roll Bonding","authors":"Mikhail Seleznev, Jennifer Mantel, Matthias Schmidtchen, Ulrich Prahl, Horst Biermann, Anja Weidner","doi":"10.1002/srin.202400472","DOIUrl":"https://doi.org/10.1002/srin.202400472","url":null,"abstract":"Accumulative roll bonding (ARB) is a repeated cladding process in which two or more sheets of material are joined together by rolling at temperatures below recrystallization. The present review is focused on ARB of high‐alloy steels, which, among other laminated metal composites (LMCs), deliver the highest mechanical properties. After a brief description of high‐strength steels, history, and state of the art of LMCs, the principal roll bonding mechanism is explained. Further, the methodology of ARB of steels and variable parameters (stacking, temperature, etc.) are discussed. Known examples of steel–steel laminates are summarized with respect to their rolling temperature and mechanical properties. Further, the main toughening mechanisms of steel‐based LMCs are listed. The most promising candidates of high‐alloy steel laminates are presented in more detail. The important deformation mechanisms of twinning‐ and transformation‐induced plasticity (TWIP and TRIP) high‐alloy steels are explained. Microstructural changes and layer bonding as well as mechanical properties and damage behavior of two‐ and four‐layered TRIP/TWIP steel laminates are illustrated, including some specific phenomena, such as deformation lenses. Finally, by summarizing the analyzed data on steel laminates, conclusions and outlook are formulated.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to optimize the heating schedule before forging and improve the breaking and deformation effects of carbides in high‐speed steel, it is of great significance to study the transformation of M2C carbides at high temperatures. The evolution of carbides in the industrial‐grade American Iron and Steel Institute M35 steel produced by electroslag remelting (ESR) is analyzed and observed using thermodynamic calculations and experimental methods. The results indicate that the carbides in the ESR ingot are mainly MC and M2C, and the microstructures of M2C carbides with the highest volume fraction are lamellar and brain like. As the heating temperature increases and holding time prolongs, the lamellar M2C carbides gradually transform into MC and M6C carbides, accompanied by protrusion, dissolution, separation, and spheroidization of the microstructure, until significant coarsening occurs at 1180 °C for 90 min. The newly transformed carbides are embedded and stacked with each other, occupying the original position of M2C carbides. Based on the theories of Gibbs free energy and atomic diffusion, the evolution mechanism of M2C carbides is discussed. Ultimately, the appropriate heating schedule is proposed, and it is validated by combining the characteristics of carbides after forging.
{"title":"Study on Evolution Behavior of Carbides in Industrial‐Grade American Iron and Steel Institute M35 High‐Speed Steel Produced by Electroslag Remelting","authors":"Wei Liang, Jing Li, Jiahao Li, Jian Chai","doi":"10.1002/srin.202400292","DOIUrl":"https://doi.org/10.1002/srin.202400292","url":null,"abstract":"In order to optimize the heating schedule before forging and improve the breaking and deformation effects of carbides in high‐speed steel, it is of great significance to study the transformation of M<jats:sub>2</jats:sub>C carbides at high temperatures. The evolution of carbides in the industrial‐grade American Iron and Steel Institute M35 steel produced by electroslag remelting (ESR) is analyzed and observed using thermodynamic calculations and experimental methods. The results indicate that the carbides in the ESR ingot are mainly MC and M<jats:sub>2</jats:sub>C, and the microstructures of M<jats:sub>2</jats:sub>C carbides with the highest volume fraction are lamellar and brain like. As the heating temperature increases and holding time prolongs, the lamellar M<jats:sub>2</jats:sub>C carbides gradually transform into MC and M<jats:sub>6</jats:sub>C carbides, accompanied by protrusion, dissolution, separation, and spheroidization of the microstructure, until significant coarsening occurs at 1180 °C for 90 min. The newly transformed carbides are embedded and stacked with each other, occupying the original position of M<jats:sub>2</jats:sub>C carbides. Based on the theories of Gibbs free energy and atomic diffusion, the evolution mechanism of M<jats:sub>2</jats:sub>C carbides is discussed. Ultimately, the appropriate heating schedule is proposed, and it is validated by combining the characteristics of carbides after forging.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The microstructure characteristics and the properties of rolled steels are significantly affected by the heat transfer and boiling phenomena occurring during the jet impingement cooling on run‐out tables (ROT). In this study, experiments are conducted using a full industrial‐scale ROT facility with rectangular plates made of low‐carbon stainless steel (type 316L). The plate is heated up to a temperature ranging from to , then rapidly impinged using a single circular water jet, and the temperature drop is captured using an infrared thermal camera (FLIR A615 25°–50 Hz type). The dissipated heat flux, estimated experimentally using a 2D inverse heat conduction analysis, ranges from 6.1 to 3.4 MW m−2 across different zones along the plate surface. The impact of different initial plate temperature on the boiling behavior is studied by developing a 2D‐computational fluid dynamics (CFD) model, and the results are closely aligned with the experimental findings. The results reveal that when estimating the heat flux from CFD simulations, the best accuracy is obtained when considering fluid temperature at a point close to the plate surface (about 1 μm above the surface). Furthermore, the maximum extracted heat flux (MHF) is significantly influenced by the initial temperature of the plate. Increasing the initial plate temperature from 500 to 900 °C led to an increase of 82% in the MHF in stagnation zone, and 137% increase in the parallel‐flow region. The CFD model presented in this study and the full calculation of the boiling curves numerically will pave the road for investigating various practical parameters in jet impingement cooling.
{"title":"Study of the Effect of Initial Plate Temperature in Jet Impingement Cooling Process","authors":"Mohamed S. Gadala, Abdulrahman Gomaa, Fahad Aslam","doi":"10.1002/srin.202400359","DOIUrl":"https://doi.org/10.1002/srin.202400359","url":null,"abstract":"The microstructure characteristics and the properties of rolled steels are significantly affected by the heat transfer and boiling phenomena occurring during the jet impingement cooling on run‐out tables (ROT). In this study, experiments are conducted using a full industrial‐scale ROT facility with rectangular plates made of low‐carbon stainless steel (type 316L). The plate is heated up to a temperature ranging from to , then rapidly impinged using a single circular water jet, and the temperature drop is captured using an infrared thermal camera (FLIR A615 25°–50 Hz type). The dissipated heat flux, estimated experimentally using a 2D inverse heat conduction analysis, ranges from 6.1 to 3.4 MW m<jats:sup>−2</jats:sup> across different zones along the plate surface. The impact of different initial plate temperature on the boiling behavior is studied by developing a 2D‐computational fluid dynamics (CFD) model, and the results are closely aligned with the experimental findings. The results reveal that when estimating the heat flux from CFD simulations, the best accuracy is obtained when considering fluid temperature at a point close to the plate surface (about 1 μm above the surface). Furthermore, the maximum extracted heat flux (MHF) is significantly influenced by the initial temperature of the plate. Increasing the initial plate temperature from 500 to 900 °C led to an increase of 82% in the MHF in stagnation zone, and 137% increase in the parallel‐flow region. The CFD model presented in this study and the full calculation of the boiling curves numerically will pave the road for investigating various practical parameters in jet impingement cooling.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xingfu Yu, Ze Wu, Tianci Hao, Yong Su, Ying Jia, Yinghua Wei
By means of salt‐bath austempering treatment, microstructure observation, X‐Ray diffraction analysis, microhardness measurement, and friction and wear performance tests for 8Cr4Mo4V steels with standard composition and with trace addition of 0.005% boron, the effect of boron on the phase composition and mechanical properties of the steel is studied. The results show that trace element boron greatly increases the content of needle‐like lower bainite in the quenched microstructure, promotes the dissolution of undissolved carbides, reduces the content of M/A island, but coarsens grains. After tempering, trace element B increases the amount of bainite generation, refines the lath martensite, and significantly promotes the precipitation of carbides, whose size is finer, and the distribution is more dispersed. In terms of mechanical properties, trace element B improves the hardness by promoting the precipitation of the second phase and refining the lath martensite, and the increase in the bainite content changes the wear mechanism and enhances the wear resistance.
通过对标准成分和微量添加 0.005% 硼的 8Cr4Mo4V 钢进行盐浴奥氏体回火处理、显微组织观察、X 射线衍射分析、显微硬度测量以及摩擦和磨损性能测试，研究了硼对钢的相组成和机械性能的影响。结果表明，微量元素硼大大增加了淬火显微组织中针状下贝氏体的含量，促进了未溶解碳化物的溶解，降低了 M/A 岛的含量，但使晶粒变得粗大。回火后，微量元素 B 增加了贝氏体的生成量，细化了板条马氏体，并显著促进了碳化物的析出，碳化物的尺寸更细，分布更分散。在机械性能方面，微量元素 B 通过促进第二相的析出和细化板条马氏体提高了硬度，贝氏体含量的增加改变了磨损机理，增强了耐磨性。
{"title":"Effect of Trace Element B on the Microstructure and Mechanical Properties of 8Cr4Mo4V Bearing Steel","authors":"Xingfu Yu, Ze Wu, Tianci Hao, Yong Su, Ying Jia, Yinghua Wei","doi":"10.1002/srin.202400501","DOIUrl":"https://doi.org/10.1002/srin.202400501","url":null,"abstract":"By means of salt‐bath austempering treatment, microstructure observation, X‐Ray diffraction analysis, microhardness measurement, and friction and wear performance tests for 8Cr4Mo4V steels with standard composition and with trace addition of 0.005% boron, the effect of boron on the phase composition and mechanical properties of the steel is studied. The results show that trace element boron greatly increases the content of needle‐like lower bainite in the quenched microstructure, promotes the dissolution of undissolved carbides, reduces the content of M/A island, but coarsens grains. After tempering, trace element B increases the amount of bainite generation, refines the lath martensite, and significantly promotes the precipitation of carbides, whose size is finer, and the distribution is more dispersed. In terms of mechanical properties, trace element B improves the hardness by promoting the precipitation of the second phase and refining the lath martensite, and the increase in the bainite content changes the wear mechanism and enhances the wear resistance.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effect of the cerium addition on the microstructure and properties of the ductile iron is investigated. The ferrocerium is added to obtain ductile iron samples with cerium contents of 10–750 ppm. In the ductile iron with a cerium content of 60 ppm, the amount and the spheroidization rate of graphites are the highest. The tensile strength of the ductile iron is 488 MPa and the elongation rate reaches 20.17%. For the ductile iron with a high toughness demand, it is necessary to add 60 ppm Ce in the ductile iron to increase the number density and spheroidization rate of graphites. The formation of CeS inclusions effectively promotes the heterogeneous nucleation of graphites, increasing the amount of graphites. The stronger carbon diffusion during the eutectic process increases the ferrite formation in the ductile iron, leading to a lower tensile strength and a higher elongation rate. When the cerium content exceeds 460 ppm, the precipitated Ce2C3 significantly reduces the performance of the ductile iron.
{"title":"Effect of Cerium Addition on Microstructure and Mechanical Properties of the Ductile Iron","authors":"Zhongyan Xie, Yubao Liu, Ying Ren, Lifeng Zhang","doi":"10.1002/srin.202400458","DOIUrl":"https://doi.org/10.1002/srin.202400458","url":null,"abstract":"The effect of the cerium addition on the microstructure and properties of the ductile iron is investigated. The ferrocerium is added to obtain ductile iron samples with cerium contents of 10–750 ppm. In the ductile iron with a cerium content of 60 ppm, the amount and the spheroidization rate of graphites are the highest. The tensile strength of the ductile iron is 488 MPa and the elongation rate reaches 20.17%. For the ductile iron with a high toughness demand, it is necessary to add 60 ppm Ce in the ductile iron to increase the number density and spheroidization rate of graphites. The formation of CeS inclusions effectively promotes the heterogeneous nucleation of graphites, increasing the amount of graphites. The stronger carbon diffusion during the eutectic process increases the ferrite formation in the ductile iron, leading to a lower tensile strength and a higher elongation rate. When the cerium content exceeds 460 ppm, the precipitated Ce<jats:sub>2</jats:sub>C<jats:sub>3</jats:sub> significantly reduces the performance of the ductile iron.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
FeCrAl alloy is considered a promising material for light water reactor fuel cladding due to its excellent elevated temperature oxidation resistance and radiation performance. The effects of 0.21 wt% Nb or 0.23 wt% La additions on the microstructure, second phase, yield strength and toughness of FeCrAl alloy are studied. The morphology and number fraction of inclusions in FeCrAl alloys are analyzed. The addition of 0.21 wt% Nb in FeCrAl alloy promotes the precipitation of nanoscale (Fe,Cr)2(Nb,Ti) Laves phase and refining grain size. The addition of La‐modified Al2O3 and MgO·Al2O3 inclusions to La2O3 and LaS, and La2O3 is favorable to promote the heterogeneous nucleation of α‐Fe. The fracture mode of the FeCrAl alloy with 0.21 wt% Nb or 0.23 wt% La transitions from dimple fracture and quasi‐cleavage fracture to dimple fracture, in comparison with Nb‐free or La‐free FeCrAl alloy. Nb and La additions improve the yield strength and toughness of FeCrAl alloy. The addition of Nb exhibits a more pronounced strengthening effect on FeCrAl alloy compared with the addition of La.
由于具有优异的高温抗氧化性和辐射性能，FeCrAl 合金被认为是一种很有前途的轻水反应堆燃料包壳材料。本文研究了添加 0.21 wt% Nb 或 0.23 wt% La 对 FeCrAl 合金微观结构、第二相、屈服强度和韧性的影响。分析了 FeCrAl 合金中夹杂物的形态和数量分数。在 FeCrAl 合金中添加 0.21 wt% 的 Nb 可促进纳米级 (Fe,Cr)2(Nb,Ti) Laves 相的析出并细化晶粒尺寸。在 La2O3 和 LaS 中加入 La 改性 Al2O3 和 MgO-Al2O3 包裹体，La2O3 有利于促进 α-Fe 的异质成核。与不含 Nb 或 La 的 FeCrAl 合金相比，含 0.21 wt% Nb 或 0.23 wt% La 的 FeCrAl 合金的断裂模式从凹陷断裂和准劈裂断裂转变为凹陷断裂。添加 Nb 和 La 可提高铁铬铝合金的屈服强度和韧性。与添加 La 相比，添加 Nb 对 FeCrAl 合金的强化效果更为明显。
{"title":"Effect of Nb and La on Precipitates, Yield Strength and Toughness of FeCrAl Alloy","authors":"Huai Zhang, Chengbin Shi, Yiwa Luo","doi":"10.1002/srin.202400553","DOIUrl":"https://doi.org/10.1002/srin.202400553","url":null,"abstract":"FeCrAl alloy is considered a promising material for light water reactor fuel cladding due to its excellent elevated temperature oxidation resistance and radiation performance. The effects of 0.21 wt% Nb or 0.23 wt% La additions on the microstructure, second phase, yield strength and toughness of FeCrAl alloy are studied. The morphology and number fraction of inclusions in FeCrAl alloys are analyzed. The addition of 0.21 wt% Nb in FeCrAl alloy promotes the precipitation of nanoscale (Fe,Cr)<jats:sub>2</jats:sub>(Nb,Ti) Laves phase and refining grain size. The addition of La‐modified Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> and MgO·Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> inclusions to La<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> and LaS, and La<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> is favorable to promote the heterogeneous nucleation of α‐Fe. The fracture mode of the FeCrAl alloy with 0.21 wt% Nb or 0.23 wt% La transitions from dimple fracture and quasi‐cleavage fracture to dimple fracture, in comparison with Nb‐free or La‐free FeCrAl alloy. Nb and La additions improve the yield strength and toughness of FeCrAl alloy. The addition of Nb exhibits a more pronounced strengthening effect on FeCrAl alloy compared with the addition of La.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The magnetite oxidation process involves magnetite surface adsorption and O2 dissociation, and the presence of impurity elements such as silicon inevitably affects the magnetite surface adsorption process. To explore and analyze the surface adsorption and oxidation behaviors of silicon‐doped Fe3O4, thermogravimetric experiments and density functional theory methods are used to investigate the physicochemical properties of this material during magnetite oxidation. The results of experiments show that with the increase of SiO2 content, the peaks of the oxidation reaction gradually migrate to the high‐temperature region, the initial oxidation temperature of the mineral increases, and the average oxidation rate decreases. The results of calculations show that when the surface system is doped with Si atoms, the relaxation time of the adsorption and dissociation of oxygen on the surface is prolonged, and the presence of Si isomerization tends to stabilize the crystal lattice structure, reduce the migration of ions, and decrease the mineral's oxidizing properties.
磁铁矿氧化过程涉及磁铁矿表面吸附和 O2 解离，硅等杂质元素的存在不可避免地影响磁铁矿表面吸附过程。为了探索和分析掺硅 Fe3O4 的表面吸附和氧化行为，采用热重实验和密度泛函理论方法研究了该材料在磁铁矿氧化过程中的物理化学性质。实验结果表明，随着 SiO2 含量的增加，氧化反应的峰值逐渐向高温区迁移，矿物的初始氧化温度升高，平均氧化速率降低。计算结果表明，当表面体系掺杂 Si 原子时，氧在表面吸附和解离的弛豫时间延长，Si 异构的存在使晶格结构趋于稳定，离子迁移减少，矿物的氧化性降低。
{"title":"Inhibition Behavior for the Oxidation of Si‐Doped Fe3O4: A Combined Ab Initio Molecular Dynamics and Experimental Study","authors":"Yaozu Wang, Xurui Liu, Ren Wang, Huiqing Jiang, Lisi Lu, Kaifa Zhang, Kexin Jiao, Fangyu Guo","doi":"10.1002/srin.202300768","DOIUrl":"https://doi.org/10.1002/srin.202300768","url":null,"abstract":"The magnetite oxidation process involves magnetite surface adsorption and O<jats:sub>2</jats:sub> dissociation, and the presence of impurity elements such as silicon inevitably affects the magnetite surface adsorption process. To explore and analyze the surface adsorption and oxidation behaviors of silicon‐doped Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub>, thermogravimetric experiments and density functional theory methods are used to investigate the physicochemical properties of this material during magnetite oxidation. The results of experiments show that with the increase of SiO<jats:sub>2</jats:sub> content, the peaks of the oxidation reaction gradually migrate to the high‐temperature region, the initial oxidation temperature of the mineral increases, and the average oxidation rate decreases. The results of calculations show that when the surface system is doped with Si atoms, the relaxation time of the adsorption and dissociation of oxygen on the surface is prolonged, and the presence of Si isomerization tends to stabilize the crystal lattice structure, reduce the migration of ions, and decrease the mineral's oxidizing properties.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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