Ahmed Abdelrahim, Mikko Iljana, Matti Aula, Timo Fabritius
In this research, the reduction of iron ore sinter in a blast furnace (BF) simulator in CO–CO2–N2‐reducing gas, simulating conditions at the BF center and wall, is investigated. Measurements from an operating BF guide the study, ensuring realistic reduction parameters. Reduction rate and extent, along with physical properties, are assessed under a temperature range of 700–1100 °C. In isothermal reduction experiments, the BF center exhibits superior conditions, particularly at 900 °C, achieving an 83.78% reduction degree compared to 27.17% at the wall for the same temperature. In this study, it is highlighted that basic iron ore sinter demonstrates higher reduction efficiency compared to acid iron ore pellets under identical BF center reducing conditions. Specific surface area and porosity measurements unveil a contrasting trend in specific surface area and porosity evolution between the BF wall and center. Surface morphology analysis reveals that the reduction in specific surface area and porosity of sinter samples at the BF center conditions at 1000–1100 °C is attributed to the sintering of the formed metallic iron. Carbon analysis confirms no carbon deposition took place during reduction. Mineralogical and physical property analyses provide detailed insights into the evolving phase composition during sinter reduction.
本研究调查了高炉(BF)模拟器在 CO-CO2-N2 还原气体中还原铁矿烧结矿的情况,模拟了高炉中心和炉壁的条件。通过对运行中的高炉进行测量来指导研究,确保还原参数符合实际情况。在 700-1100 °C 的温度范围内,对还原速率和程度以及物理性质进行了评估。在等温还原实验中,BF 中心显示出优越的条件,尤其是在 900 ℃ 时,在相同温度下,BF 中心的还原度达到 83.78%,而壁的还原度仅为 27.17%。这项研究强调,在相同的 BF 中心还原条件下,碱性铁矿烧结矿的还原效率高于酸性铁矿球团矿。比表面积和孔隙率测量结果表明,碱性铁矿烧结矿壁和中心的比表面积和孔隙率变化趋势截然不同。表面形态分析表明,在 1000-1100 °C 的烧结炉中心条件下,烧结样品比表面积和孔隙率的减少是由于形成的金属铁烧结所致。碳分析证实在还原过程中没有碳沉积。矿物学和物理性质分析提供了烧结矿还原过程中相组成演变的详细情况。
{"title":"Impact of Radial Position on Iron Ore Sinter Reduction and Microstructure at 700–1100 °C","authors":"Ahmed Abdelrahim, Mikko Iljana, Matti Aula, Timo Fabritius","doi":"10.1002/srin.202400339","DOIUrl":"https://doi.org/10.1002/srin.202400339","url":null,"abstract":"In this research, the reduction of iron ore sinter in a blast furnace (BF) simulator in CO–CO<jats:sub>2</jats:sub>–N<jats:sub>2</jats:sub>‐reducing gas, simulating conditions at the BF center and wall, is investigated. Measurements from an operating BF guide the study, ensuring realistic reduction parameters. Reduction rate and extent, along with physical properties, are assessed under a temperature range of 700–1100 °C. In isothermal reduction experiments, the BF center exhibits superior conditions, particularly at 900 °C, achieving an 83.78% reduction degree compared to 27.17% at the wall for the same temperature. In this study, it is highlighted that basic iron ore sinter demonstrates higher reduction efficiency compared to acid iron ore pellets under identical BF center reducing conditions. Specific surface area and porosity measurements unveil a contrasting trend in specific surface area and porosity evolution between the BF wall and center. Surface morphology analysis reveals that the reduction in specific surface area and porosity of sinter samples at the BF center conditions at 1000–1100 °C is attributed to the sintering of the formed metallic iron. Carbon analysis confirms no carbon deposition took place during reduction. Mineralogical and physical property analyses provide detailed insights into the evolving phase composition during sinter reduction.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219548","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}
This study examines the dependent relationship between microstructure, mechanical properties, and corrosion performance on the wire arc additive manufactured (WAAM) ER2209 duplex stainless steel (DSS). DSS is renowned for its corrosion resistance and mechanical strength, making it favorable for various applications. This study uses the gas metal arc welding (GMAW)‐ based WAAM technique to fabricate the wall structure using ER2209 DSS filler wire. Fine, equiaxed dendrites are formed along the build direction, with the austenite phase exceeding 70% due to the repeated heating and slow cooling inherent to WAAM process. X‐ray diffraction (XRD) confirms no brittle intermetallic phases. The results shows that varying austenite‐ferrite fractions significantly influences the anisotropy in mechanical properties between build and deposit directions. Along the build direction, the varying phase fraction causes difference in hardness of 19.59 HV0.3 and tensile strength of 20 MPa. The maximum tensile strength (787.08 MPa) is observed in the deposit direction, with a 52 MPa difference between the build and deposit directions. Tafel and EIS measurements indicated that WAAM samples corrosion resistance was almost close to wrought 2205 DSS. This study highlights WAAM's potential for defect‐free DSS parts and suggests post‐heat treatment to optimize microstructure and mechanical properties.
{"title":"Microstructural Evolution, Mechanical and Electrochemical Performance of Duplex Stainless Steel Fabricated by Wire Arc Additive Manufacturing with ER2209 Filler Wire","authors":"Sanjeevi Prakash Karunanithi, Rajesh Kannan Arasappan, Siva Shanmugam Nallathambi","doi":"10.1002/srin.202400425","DOIUrl":"https://doi.org/10.1002/srin.202400425","url":null,"abstract":"This study examines the dependent relationship between microstructure, mechanical properties, and corrosion performance on the wire arc additive manufactured (WAAM) ER2209 duplex stainless steel (DSS). DSS is renowned for its corrosion resistance and mechanical strength, making it favorable for various applications. This study uses the gas metal arc welding (GMAW)‐ based WAAM technique to fabricate the wall structure using ER2209 DSS filler wire. Fine, equiaxed dendrites are formed along the build direction, with the austenite phase exceeding 70% due to the repeated heating and slow cooling inherent to WAAM process. X‐ray diffraction (XRD) confirms no brittle intermetallic phases. The results shows that varying austenite‐ferrite fractions significantly influences the anisotropy in mechanical properties between build and deposit directions. Along the build direction, the varying phase fraction causes difference in hardness of 19.59 HV<jats:sub>0.3</jats:sub> and tensile strength of 20 MPa. The maximum tensile strength (787.08 MPa) is observed in the deposit direction, with a 52 MPa difference between the build and deposit directions. Tafel and EIS measurements indicated that WAAM samples corrosion resistance was almost close to wrought 2205 DSS. This study highlights WAAM's potential for defect‐free DSS parts and suggests post‐heat treatment to optimize microstructure and mechanical properties.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219584","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}
Manendra Singh Parihar, Sri Harsha Nistala, Rajan Kumar, Sristy Raj, Adity Ganguly, Venkataramana Runkana
Blast furnace is a multiphase counter‐current packed bed reactor that converts iron‐bearing materials such as lumps, sinter, and pellets into hot metal using metallurgical coke and pulverized coal. The quality of input materials has a significant impact on furnace performance, hot metal quality and steel plant economics. It is difficult for operators to identify the optimal settings required for efficient and safe operation based on their experience alone, given the large number of furnace parameters. A multiobjective optimization problem for maximizing furnace productivity (PROD) and minimizing fuel rate (FR) with constraints on hot metal silicon (HMSi) and temperature (HMT) is formulated and solved using a genetic algorithm. Machine learning (ML) models are developed for PROD, FR, HMSi, and HMT and tested with data from an industrial blast furnace. Pareto‐optimal solutions along with optimal settings for key manipulated variables are obtained. It is demonstrated that PROD and FR can be improved by ≈3–5% at steady state. The overall ML model‐based optimization framework can be used as part of a blast furnace digital twin system to operate the furnace efficiently in real‐time for the given quality of raw materials.
{"title":"Optimization of Blast Furnace Ironmaking Using Machine Learning and Genetic Algorithms","authors":"Manendra Singh Parihar, Sri Harsha Nistala, Rajan Kumar, Sristy Raj, Adity Ganguly, Venkataramana Runkana","doi":"10.1002/srin.202300788","DOIUrl":"https://doi.org/10.1002/srin.202300788","url":null,"abstract":"Blast furnace is a multiphase counter‐current packed bed reactor that converts iron‐bearing materials such as lumps, sinter, and pellets into hot metal using metallurgical coke and pulverized coal. The quality of input materials has a significant impact on furnace performance, hot metal quality and steel plant economics. It is difficult for operators to identify the optimal settings required for efficient and safe operation based on their experience alone, given the large number of furnace parameters. A multiobjective optimization problem for maximizing furnace productivity (PROD) and minimizing fuel rate (FR) with constraints on hot metal silicon (HMSi) and temperature (HMT) is formulated and solved using a genetic algorithm. Machine learning (ML) models are developed for PROD, FR, HMSi, and HMT and tested with data from an industrial blast furnace. Pareto‐optimal solutions along with optimal settings for key manipulated variables are obtained. It is demonstrated that PROD and FR can be improved by ≈3–5% at steady state. The overall ML model‐based optimization framework can be used as part of a blast furnace digital twin system to operate the furnace efficiently in real‐time for the given quality of raw materials.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219550","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}
Zhiwei Zhu, Yonghuan Guo, Xinran Zhang, Xiangning Lu, Xiwen Wang
The steel/aluminum dissimilar metal welding plays a significant role in lightweighting automotive structures. However, the formation of hard and brittle intermetallic compounds (IMCs) in steel/aluminum welded joints severely compromises their mechanical performance. Nano ceramic particles such as TiC possess characteristics that inhibit the diffusion of Fe and Al, thereby exhibiting a significant advantage in suppressing IMCs formation in steel/aluminum welded joints. In this study, an optimized laser‐welding process is employed to investigate the mechanical properties of steel/aluminum dissimilar metal joints with different concentrations of TiC nanoparticles. It is aimed to determine the optimal TiC addition concentration by comparing the mechanical performance. Additionally, the inhibitory effect of TiC particles on the formation and growth of brittle Fe–Al IMCs is explored through an analysis of IMCs growth kinetics. In the research results, it is shown that the optimal TiC addition concentration is 1%. At this concentration, the tensile strength of the steel/aluminum welded joint reaches 98.29 MPa, showing a remarkable improvement of 32.65% compared to the sample without TiC addition. The addition of TiC particles suppresses the mutual diffusion between Fe and Al, reduces the generation of brittle IMCs, and enhances the mechanical performance of the steel/aluminum joint.
{"title":"Effects of Pre‐Placed Nano‐TiC Powder on the Performance of Steel/Aluminum Laser Welded Joints","authors":"Zhiwei Zhu, Yonghuan Guo, Xinran Zhang, Xiangning Lu, Xiwen Wang","doi":"10.1002/srin.202400470","DOIUrl":"https://doi.org/10.1002/srin.202400470","url":null,"abstract":"The steel/aluminum dissimilar metal welding plays a significant role in lightweighting automotive structures. However, the formation of hard and brittle intermetallic compounds (IMCs) in steel/aluminum welded joints severely compromises their mechanical performance. Nano ceramic particles such as TiC possess characteristics that inhibit the diffusion of Fe and Al, thereby exhibiting a significant advantage in suppressing IMCs formation in steel/aluminum welded joints. In this study, an optimized laser‐welding process is employed to investigate the mechanical properties of steel/aluminum dissimilar metal joints with different concentrations of TiC nanoparticles. It is aimed to determine the optimal TiC addition concentration by comparing the mechanical performance. Additionally, the inhibitory effect of TiC particles on the formation and growth of brittle Fe–Al IMCs is explored through an analysis of IMCs growth kinetics. In the research results, it is shown that the optimal TiC addition concentration is 1%. At this concentration, the tensile strength of the steel/aluminum welded joint reaches 98.29 MPa, showing a remarkable improvement of 32.65% compared to the sample without TiC addition. The addition of TiC particles suppresses the mutual diffusion between Fe and Al, reduces the generation of brittle IMCs, and enhances the mechanical performance of the steel/aluminum joint.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219551","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}
Shuai He, Zhi‐Feng Li, Xin Liu, Xu‐Ming Liu, Jun‐Sheng Wang
The oxide scale on the surface of hot‐rolled low‐carbon steel strips is subjected to isothermal reduction in 10 vol%H2–Ar and 20 vol%H2–Ar environments to simulate the reduction process that occurs in a continuous annealing furnace. The influence of hydrogen concentration on the reduction kinetics and the microstructural evolution of the oxide scale after reduction at temperatures ranging from 450 to 850 °C for a duration of 20 min are investigated in detail. The mass changes of the oxide scale in the two gases are quantified using a thermogravimetric analyzer. This data is then employed to calculate the reduction rate constant and the apparent activation energy. To examine the microstructure and element distribution, electron probe microanalysis and energy‐dispersive spectrometry are employed. An novel approach is also undertaken to assess the reduction degree of the oxide scale by measuring surface microhardness. In the findings, it is indicated that an increase in hydrogen concentration served primarily to accelerate the reduction reaction within the temperature ranges of 450–550 and 800–850 °C. Meanwhile, the mechanism of physical transformation of oxide scale, the microstructure of reduction layer, and hydrogen concentration on reduction efficiency under different reaction stages are proposed.
{"title":"Isothermal Reduction Behavior of Oxide Scale on the Surface of Hot‐Rolled Strip Steel Under Different Hydrogen Concentrations","authors":"Shuai He, Zhi‐Feng Li, Xin Liu, Xu‐Ming Liu, Jun‐Sheng Wang","doi":"10.1002/srin.202400375","DOIUrl":"https://doi.org/10.1002/srin.202400375","url":null,"abstract":"The oxide scale on the surface of hot‐rolled low‐carbon steel strips is subjected to isothermal reduction in 10 vol%H<jats:sub>2</jats:sub>–Ar and 20 vol%H<jats:sub>2</jats:sub>–Ar environments to simulate the reduction process that occurs in a continuous annealing furnace. The influence of hydrogen concentration on the reduction kinetics and the microstructural evolution of the oxide scale after reduction at temperatures ranging from 450 to 850 °C for a duration of 20 min are investigated in detail. The mass changes of the oxide scale in the two gases are quantified using a thermogravimetric analyzer. This data is then employed to calculate the reduction rate constant and the apparent activation energy. To examine the microstructure and element distribution, electron probe microanalysis and energy‐dispersive spectrometry are employed. An novel approach is also undertaken to assess the reduction degree of the oxide scale by measuring surface microhardness. In the findings, it is indicated that an increase in hydrogen concentration served primarily to accelerate the reduction reaction within the temperature ranges of 450–550 and 800–850 °C. Meanwhile, the mechanism of physical transformation of oxide scale, the microstructure of reduction layer, and hydrogen concentration on reduction efficiency under different reaction stages are proposed.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219554","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 production of high‐carbon hard wire steel at high speeds necessitates the use of appropriate technical support to ensure cost‐efficiency and optimal performance of the special steel casting machine. This study investigates the industrial application of single‐roller hard reduction technology in a domestic steel plant for the production of high‐carbon hard wire steel billets, specifically of section 165 × 165 mm. The produced billets meet all customer specifications and demonstrate the benefits of this approach, including lower comprehensive costs, suitability for modification, and advanced technical concepts. These features make this method compatible with a wide range of billet casting machines, from standard to specialized. In this research, discussion is done on the reduction process, the layout of withdrawal and straightening units (WSUs), and the optimal casting speed. It is concluded that bow‐type billet casting machines using rigid dummy bars can achieve single‐roller hard reduction by only three WSUs, offering lower comprehensive costs and suitability for modification. This approach is particularly beneficial for small billet casting machines undergoing an upgrade from general to high‐quality and ultimately to special steel. During the process of increasing the central density of the billet and improving central defects using single‐roller hard reduction technology, it is observed that defects in the central region gravitated toward the center. For billet casting machines with a bow radius of 10 m, considering process tolerance, the maximum casting speeds achievable with single‐roller hard reduction are 2.95–3.40 m min−1 for a section of 150 × 150 mm, 2.60–3.0 m min−1 for a section of 160 × 160 mm, and 2.45–2.80 m min−1 for a section of 165 × 165 mm. To achieve higher casting speeds for high‐carbon hard wire steel, it is necessary to modify the machine configuration to flexible dummy bars.
要高速生产高碳硬线钢,就必须使用适当的技术支持,以确保特种钢铸造机的成本效益和最佳性能。本研究调查了单辊硬减径技术在国内一家钢铁厂生产高碳硬线钢方坯(截面尺寸为 165 × 165 毫米)中的工业应用。所生产的钢坯符合客户的所有规格要求,并证明了这种方法的优势,包括综合成本较低、适合改装以及技术理念先进。这些特点使这种方法与从标准到专用的各种方坯铸造机兼容。在这项研究中,对还原过程、退坯和矫直装置(WSU)的布局以及最佳铸造速度进行了讨论。研究得出结论,使用刚性虚杆的弓形小方坯铸造机只需三个 WSU 即可实现单辊硬减径,综合成本较低,适合改装。这种方法尤其适用于从普通钢升级到优质钢,并最终升级到特种钢的小型方坯铸造机。在使用单辊硬减径技术提高方坯中心密度和改善中心缺陷的过程中,发现中心区域的缺陷向中心倾斜。对于弓形半径为 10 米的方坯铸造机,考虑到工艺公差,采用单辊硬齿面技术实现的最大铸造速度为:截面为 150 × 150 毫米的铸坯,2.95-3.40 m min-1;截面为 160 × 160 毫米的铸坯,2.60-3.0 m min-1;截面为 165 × 165 毫米的铸坯,2.45-2.80 m min-1。为了提高高碳硬线钢的浇铸速度,有必要对机器配置进行修改,使其具有灵活的假棒材。
{"title":"Implementing Single‐Roller Hard Reduction Technology for High‐Speed Production of High‐Carbon Hard Wire Steel Billets","authors":"Wen‐Xing Gao, Chang‐Chuan Xie, Jianke Li, Richeng Liang, Jiaming Liu, Liang Qian","doi":"10.1002/srin.202400250","DOIUrl":"https://doi.org/10.1002/srin.202400250","url":null,"abstract":"The production of high‐carbon hard wire steel at high speeds necessitates the use of appropriate technical support to ensure cost‐efficiency and optimal performance of the special steel casting machine. This study investigates the industrial application of single‐roller hard reduction technology in a domestic steel plant for the production of high‐carbon hard wire steel billets, specifically of section 165 × 165 mm. The produced billets meet all customer specifications and demonstrate the benefits of this approach, including lower comprehensive costs, suitability for modification, and advanced technical concepts. These features make this method compatible with a wide range of billet casting machines, from standard to specialized. In this research, discussion is done on the reduction process, the layout of withdrawal and straightening units (WSUs), and the optimal casting speed. It is concluded that bow‐type billet casting machines using rigid dummy bars can achieve single‐roller hard reduction by only three WSUs, offering lower comprehensive costs and suitability for modification. This approach is particularly beneficial for small billet casting machines undergoing an upgrade from general to high‐quality and ultimately to special steel. During the process of increasing the central density of the billet and improving central defects using single‐roller hard reduction technology, it is observed that defects in the central region gravitated toward the center. For billet casting machines with a bow radius of 10 m, considering process tolerance, the maximum casting speeds achievable with single‐roller hard reduction are 2.95–3.40 m min<jats:sup>−1</jats:sup> for a section of 150 × 150 mm, 2.60–3.0 m min<jats:sup>−1</jats:sup> for a section of 160 × 160 mm, and 2.45–2.80 m min<jats:sup>−1</jats:sup> for a section of 165 × 165 mm. To achieve higher casting speeds for high‐carbon hard wire steel, it is necessary to modify the machine configuration to flexible dummy bars.","PeriodicalId":21929,"journal":{"name":"steel research international","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219561","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}