Search Sites

ISIJ International Advance Publication

ISIJ International
belloff

Grid List Abstracts

ONLINE ISSN: 1347-5460
PRINT ISSN: 0915-1559
Publisher: The Iron and Steel Institute of Japan

Backnumber

  1. Vol. 64 (2024)

  2. Vol. 63 (2023)

  3. Vol. 62 (2022)

  4. Vol. 61 (2021)

  5. Vol. 60 (2020)

  6. Vol. 59 (2019)

  7. Vol. 58 (2018)

  8. Vol. 57 (2017)

  9. Vol. 56 (2016)

  10. Vol. 55 (2015)

  11. Vol. 54 (2014)

  12. Vol. 53 (2013)

  13. Vol. 52 (2012)

  14. Vol. 51 (2011)

  15. Vol. 50 (2010)

  16. Vol. 49 (2009)

  17. Vol. 48 (2008)

  18. Vol. 47 (2007)

  19. Vol. 46 (2006)

  20. Vol. 45 (2005)

  21. Vol. 44 (2004)

  22. Vol. 43 (2003)

  23. Vol. 42 (2002)

  24. Vol. 41 (2001)

  25. Vol. 40 (2000)

  26. Vol. 39 (1999)

  27. Vol. 38 (1998)

  28. Vol. 37 (1997)

  29. Vol. 36 (1996)

  30. Vol. 35 (1995)

  31. Vol. 34 (1994)

  32. Vol. 33 (1993)

  33. Vol. 32 (1992)

  34. Vol. 31 (1991)

  35. Vol. 30 (1990)

  36. Vol. 29 (1989)

ISIJ International Advance Publication

Effect of Iron Oxide Dissolution on Thermochemical Property of Solid Solution between Ca2SiO4 and Ca3P2O8 at 1573 K

Keijiro Saito, Yoshiyuki Makino, Masakatsu Hasegawa

Abstract

The key to a better understanding of phosphorus removal from hot metal is to know the thermochemical properties of solid solution between Ca2SiO4 and Ca3P2O8. Although the solid solutions would inevitably incorporate iron oxide in steelmaking slags, there is a still lack of knowledge about the solid solutions containing iron oxide. The present study focused on the effect of FeO dissolution on the activities of components in the Ca2SiO4-Ca3P2O8 solid solution. The P2O5 activities were measured in the solid solution containing FeO at 1573 K. Subsequently, the activities of Ca2SiO4, Ca3P2O8, and Fe2SiO4 were derived from the Gibbs-Duhem equation with the measured P2O5 activities and reported FeO activities. When iron oxide dissolved into the Ca2SiO4-Ca3P2O8 solid solution, the Ca3P2O8 activity decreased, while the Ca2SiO4 activity was insensitive. As a result, the dissolution of iron oxide into the solid solution caused a drastic decrease in the P2O5 activity.

Bookmark

Share it with SNS

Article Title

Effect of Iron Oxide Dissolution on Thermochemical Property of Solid Solution between Ca2SiO4 and Ca3P2O8 at 1573 K

Constitutive Description of Flow Curve for Duplex Titanium Alloy for Hot Forming under Elevated Temperature

Yuki Shimomura, Hyung-Won Park, Hyeon-Woo Park, Yuji Sato, Jun Yanagimoto

Abstract

A novel integrated constitutive equation of the flow curve for Ti–6Al–4V alloys is proposed by incorporating the effects of phase fraction in the hot-forging temperature range. The flow curve was obtained using hot-compression tests in the temperature range of 750–1050 °C and strain rate range of 1–25 s-1. The effects of friction and deformation heat generated during compression were corrected using the inverse analysis method to identify the ideal uniaxial flow curve. The obtained stress parameters were satisfactorily regressed using the rule of mixtures on the α and β phases considering changes in the phase fraction. The integrated flow curve equation incorporating the rule of mixtures of the two phases effectively expressed the flow curve throughout the investigated temperature range. The internal microstructural observation showed that the continuous dynamic recrystallization of the α phase is dominant in the α+β two-phase region, while the deformation of the β phase becomes dominant just below the β transus. The constitutive equation presented here is in good agreement with the temperature dependence of the microstructure.

Bookmark

Share it with SNS

Article Title

Constitutive Description of Flow Curve for Duplex Titanium Alloy for Hot Forming under Elevated Temperature

Hydrogen trapping and precipitation of alloy carbides in molybdenum added steels and vanadium added steels

Shunsuke Taniguchi, Miyuri Kameya, Yukiko Kobayashi, Kazuma Ito, Shingo Yamasaki

Abstract

Martensitic steels of Fe-0.1%C-2%Mn-1.6%Mo and Fe-0.1%C-2%Mn-0.2%V alloys were subjected to tempering at 873 K to investigate the hydrogen trapping of Mo and V carbides. We analyzed the alloy carbides in detail via atomic-resolution scanning transmission electron microscopy and atom probe tomography, and evaluated hydrogen trapping energy via ab initio calculations. The hydrogen content of the Mo-added steel tempered for 1.8 ks increased from that of the quenched Mo-added steel, and the hydrogen content monotonically decreased as the tempering time increased. The hydrogen content of the V-added steels increased during tempering up to 7.2 ks and then remained almost constant. A plate-shaped B1-type Mo carbide with a chemical composition of MoC0.50 precipitated in the Mo-added steel tempered for 3.6 ks. Needle-shaped HCP Mo2C precipitated and the B1-type Mo carbide decreased in the Mo-added steel tempered for 14.4 ks. A plate-shaped B1-type V carbide with a chemical composition of VC0.75 precipitated in the V-added steel tempered for 14.4 ks. We found a positive correlation between the hydrogen content and the product of the interface area and the carbon vacancy fraction of the B1-type alloy carbide. The hydrogen trapping energy of the carbon vacancy at the interface between BCC-Fe and the B1-type Mo carbide was higher than that of the interstitial sites in BCC-Fe. These results suggest that the main trapping site in the tempered Mo-added steel was the carbon vacancy at the interface of B1-type MoC0.50, not HCP Mo2C.

Bookmark

Share it with SNS

Article Title

Hydrogen trapping and precipitation of alloy carbides in molybdenum added steels and vanadium added steels

Assessing the banding degree of martensite in the bainite matrix through EPMA

Yang Meng, Chunlian Yan, Juan Wen, Xinhua Ju

Abstract

Due to the difficulty of distinguishing the grain boundaries between martensite and bainite in fast-cooling microstructures, few good methods were reported to accurately assess the banding degree of martensite or bainite. In present work, a novel method has been developed to meet this challenge. The hot rolled bars of drill steel 23CrMoNi, which had martensite bands distributed in the bainite matrix, were used in this research. The banded structure in this hot rolled 23CrMoNi was closely related to the segregation of the alloying elements such as Cr, Ni and Mo. These alloying element mappings were first acquired by electron probe micro analyzer (EPMA). A new data processing method was developed to correlate the segregated element mapping with the banded structure. The banding assessment was conducted on the processed binary images of element mappings according to ASTM E1268-19. This method was well verified by assessing the banded pearlite in the ferrite matrix, whose banding degree can be easily accessed through microstructure difference. It was shown from the quantitative analysis results of the hot rolled 23CrMoNi that the banded distribution of martensite was greatly optimized by the adjustment of hot rolling process.

Bookmark

Share it with SNS

Article Title

Assessing the banding degree of martensite in the bainite matrix through EPMA

Dissolution of Carbon-Containing Species in CaO-SiO2-Al2O3 Slag

Qiuju Li, Cong Liang, Bowen Han

Abstract

The acceleration of the carburizing and melting processes in reduced iron is critical for reducing energy consumption and CO2 emissions produced by the steel industry. The aims of the study were to clarify the carbon dissolution reactions and diffusion processes in molten slag. A combined approach utilizing Raman spectroscopy and XPS was employed to investigate the relationship between carbon-containing species and slag composition in the CaO-SiO2-Al2O3 slag system. The Raman spectra indicated that carbon dissolved in slag in the form of carbides, carbonates, and graphitic structures. The proportion of carbide ions in the slag increased from 64.2% to 74.7%, and the proportion of graphitic structures decreased from 19.7% to 7.4% as the slag's basicity increased. The carbon dissolution mechanism in slag involved the reaction of carbon with dissolved oxide ions and oxygen-containing anions in the slag. This formed carbon-containing species such as CO32-, C22-, and graphitic structures that diffused in the slag and subsequently underwent carburization and deposition at the iron interface.

Bookmark

Share it with SNS

Article Title

Dissolution of Carbon-Containing Species in CaO-SiO2-Al2O3 Slag

Effect of biocarbon addition on metallurgical properties of mill scale-based auger pressing briquettes

Olli Vitikka, Mikko Iljana, Anne Heikkilä, Illia Tkalenko, Oleksii Kovtun, Nikita Koriuchev, Daniel Shehovsov, Timo Fabritius

Abstract

This work focused on the usage of bio-based and secondary iron and steelmaking raw materials. Auger pressing briquettes, cold-bonded agglomerates made from by-products, mainly mill scale (80%), were successfully tested in industrial-scale blast furnace (BF) trials. The briquettes from industrial production were studied in two different laboratory-scale reduction experiments to compare them to laboratory-made briquettes. A blast furnace simulator (BFS) device was utilized in the simulations mimicking the temperature and gas profiles of an actual BF process. A reduction under load (RUL) device enabled the simulation of the physical load under reducing conditions. To determine how the high-temperature properties of the self-reducing briquettes depend on the amount of biocarbon, a bio-based reducing agent (2–10 %) was added to the laboratory-scale briquettes that already contained 5.6% total carbon mainly originating from BF dust. For the recipes studied, a weight loss of about 30% under reducing conditions leads to the disintegration of a briquette under load. Based on the BFS experiments, adding biocarbon to the recipe was profitable in terms of a self-reducing effect up to 6% when the total carbon content was 11%. The RUL experiments showed that the structure of the briquette became extremely plastic with the addition of 4% biocarbon which covers 39% of the total carbon contained in the briquette. This was the upper limit for biocarbon addition due to telescoping and disintegration followed by the formation of fines. The industrial briquettes used in the BF corresponded well to the laboratory-made briquettes in terms of metallurgical properties.

Bookmark

Share it with SNS

Article Title

Effect of biocarbon addition on metallurgical properties of mill scale-based auger pressing briquettes

Liquid-Liquid Phase Separation and Phase Distribution in CaO-P2O5-FeO Slag for Phosphorus Recovery

Yu-ichi Uchida, Kenji Nakase, Katsunori Takahashi

Abstract

Supposing to utilize the slag with high P2O5 content as a new phosphorus resource produced from a novel steelmaking process, a fundamental investigation was carried out with particular focus on spontaneous liquid-liquid phase separation occurring in the system CaO-P2O5-FeO for effective phosphorus recovery. At 1773K, two types of phase separation, which is a double-layered or a dispersed structure of two liquid phases, were observed according to the bulk composition. The double layers separated vertically and consisted of the phase with higher P2O5 content over 40 mass%, and the phase with higher FeO content over 90 mass%. Such structure corresponds to the liquid-liquid separation in the compositional region which is located in higher P2O5 content (upper side) against the tie line between Ca3P2O8 – FeO apex on the isothermal section of CaO-P2O5-FeO ternary system. At 1673K, various separation was observed such as a double-layer or a dispersed structure of two liquid phases, and a coexistence of solid/liquid phases. The slag with the bulk composition lying in the upper two liquid region showed the double-layered structure, giving a promising result for phosphorus recovery through phosphate concentration. The condition for formation of double-layered structure was considered based on the index originally proposed for co-continuity in polymer blends processing, which consists of viscosity and volume fraction of the co-existing phases. The index was found to represent a specific condition for making co-continuous phases in this study and would be significant in view of effective phosphorus recovery.

Readers Who Read This Article Also Read

Bookmark

Share it with SNS

Article Title

Liquid-Liquid Phase Separation and Phase Distribution in CaO-P2O5-FeO Slag for Phosphorus Recovery

Effect of glycerol mechanical excitation on the phase evolution and hydration activity of steel slag

Peng Yao Liu, Guo Peng Li, Meng Jie Tao, Xi Zhang, Jun Guo Li, Shuai Chao, Ya Ling Zhang, Yi Ming Duan, Xin Ning, Chong Yu Niu, Guo Zhang Tang

Abstract

During the slow cooling process of steel slag, the crystals of inert mineral phases (C2F, RO phases) and active mineral phases (C2S, C3S) adhere and grow, and the irregular interlocking, embedding, filling, stacking, and coating between mineral phases seriously affect the hydration activity of active mineral phases in steel slag. Therefore, this article selects glycerol (C3H8O3) as a grinding aid to mechanically excite steel slag, exploring the mineral phase evolution and hydration activity excitation mechanism of steel slag under different process parameters. C3H8O3 mechanical excitation refined the steel slag particles, increased porosity, increased specific surface area, and caused peeling behavior between the rough surface active mineral phases (C2S, C3S) of the steel slag particles and the smooth surface inert mineral phase C2F with sharp angular protrusions. When the addition amount of C3H8O3 is 0.24 wt% and the ball milling time is 90 minutes, the mechanical excitation effect of steel slag is the best. The total mass fraction of C2S and C3S increases by 14.3 wt%, while the mass fraction of C2F decreases by 19.3 wt%. The mechanical excitation of C3H8O3 can cause the steel slag to germinate cracks at the interface of each phase, and a porous honeycomb structure composed of calcium hydroxide (CH) and calcium silicon hydrogel (C-S-H) appears during the hydration process, producing a large number of acicular ettringite (AFt), effectively improving the early hydration activity of steel slag.

Bookmark

Share it with SNS

Article Title

Effect of glycerol mechanical excitation on the phase evolution and hydration activity of steel slag

Kinetics analysis of iron oxide reduction by solid carbon in HIsmelt ironmaking slag

Zhenyang Wang, Ruishuai Si, Jing Pang, Jixiang Han, Wei Ren, Ziluo Chen, Jianliang Zhang, Shushi Zhang, Dewen Jiang, Song Zhang

Abstract

The HIsmelt process is a new molten reduction ironmaking technology with lower energy consumption and carbon emissions than the traditional blast furnace ironmaking route. In the HIsmelt smelting process, the reaction process between solid carbon and iron-bearing slag has its own characteristics. To investigate the kinetic mechanism of iron oxide reduction in slag, the degree of conversion was characterized by measuring the change of CO content of the generated gas during the experiments and analyzed by combining the model fitting method. The experimental results showed the highest agreement with the Avrami-Erofeev equation. The rate-controlling mechanism for the reduction of iron oxides in the slag was judged to be the random nucleation and subsequent growth of the products. In the study, the rate-controlling mechanism and the kinetic parameters of the reduction reaction of iron oxide in slag have been obtained.

Bookmark

Share it with SNS

Article Title

Kinetics analysis of iron oxide reduction by solid carbon in HIsmelt ironmaking slag

Effect of Nano-sized Cu-Rich Phase on Microbiological Corrosion Behavior of Cu and Ni-Added Steel for Oil Country Tubular Goods

Xianbo Shi, Yunpeng Zeng, Yi Ren, Wei Yan, Xu Yang, Guanghui Wu, Yiyin Shan, Ke Yang

Abstract

The Cu-bearing antibacterial low-alloyed steel pipe is a new strategy to mitigate microbiologically influenced corrosion (MIC) for oil and gas industry. It can effectively alleviate the occurrence of bacterial corrosion, but cannot avoid the MIC totally. To enhance the resistance to MIC of Cu-bearing low-alloyed steel, the MIC behavior of a Cu and Ni-added experimental steel with different nano-sized Cu-rich precipitates was investigated. Results showed that the synergistic effect of antibacterial ability of nano-sized Cu-rich precipitates and protective Cu-Ni enrichment layer formed on the steel surface contributed to the good MIC resistance. Although the Cu-rich precipitates possessed antibacterial actively, they also increased the surface potential difference simultaneously, resulting in promoting MIC. The extremely fine and dispersed Cu-rich precipitates with high-density was the preferred microstructure to achieve better MIC resistance for the steel.

Bookmark

Share it with SNS

Article Title

Effect of Nano-sized Cu-Rich Phase on Microbiological Corrosion Behavior of Cu and Ni-Added Steel for Oil Country Tubular Goods

Multiscale finite element analysis of yield-point phenomenon in the ferrite–pearlite duplex steels

Shinnosuke Yanagawa, Ikumu Watanabe

Abstract

The yield-point phenomena in ferrite–pearlite duplex steels were investigated using multiscale computational simulations. In these multiscale simulations, the stress–strain relationship of the ferrite phase was characterized by an elastoplastic constitutive model considering the stress-drop behavior, and its material constants were determined by minimizing the residual error between a computational simulation and a tensile test experiment, where the yield-point phenomenon in a tensile test of ferrite steel was reproduced. Using the determined material response of the ferrite phase, finite element analyses of the ferrite–pearlite duplex microstructure were executed to scrutinize both the macroscopic material response and microscopic deformation mechanisms. Subsequently, finite element analyses of tensile tests, based on numerical results from microstructural analyses, were carried out to replicate the yield-point phenomena in ferrite–pearlite duplex steels. Consequently, the study characterized the strengthening effect of the pearlite constituent while considering microscopic heterogeneity and yield-point phenomena in the ferrite phase. The findings from the multiscale simulations underscored the necessity for a more accurate estimation of local mechanical properties in both the ferrite phase and pearlite constituent for quantitative simulations.

Bookmark

Share it with SNS

Article Title

Multiscale finite element analysis of yield-point phenomenon in the ferrite–pearlite duplex steels

Dependence of mechanical properties and deformation behavior of TRIP-FeMnCoCrAl dual-phase high-entropy alloy on grain size and strain rate

Jie Li, Bo Zhang, Lichong Niu, Minghe Zhang, Yunli Feng

Abstract

Fe50Mn30Co10Cr10 dual-phase metastable high-entropy alloys(HEAS) have gained significant attention for their outstanding mechanical properties. However, limited research has explored the relationship between grain size and strain rate sensitivity (SRS) in dual-phase HEAS. Current investigations primarily focus on pure metals and single-phase FCC HEAS. To address this gap, this study examines the impact of grain size on the deformation behavior and SRS of TRIP-(Fe50Mn30Co10Cr10)97Al3 dual-phase HEAS. Two variants of dual-phase HEAS were prepared, distinguished by their grain sizes (2.86 μm, labeled Fine Grain or FG, and 5.25 μm, termed Coarse Grain or CG), via the vacuum melting method. Subsequent tensile tests were conducted at varying strain rates, ranging from 0.001/s to 0.02/s. The findings unveil a robust grain size dependency in the phase transformation and deformation twinning of the (Fe50Mn30Co10Cr10)97Al3 dual-phase HEA during tensile deformation. Within the FeMnCoCrAl HEA system, characterized by a dual-phase structure, both TRIP (Transformation-Induced Plasticity) and TWIP (Twinning-Induced Plasticity) effects intensify with increasing grain size. Additionally, as the strain rate increases, the TRIP effect gradually diminishes while the TWIP effect strengthens. Notably, the strain rate sensitivity index 'm' exhibits a downward trend with an increase in grain size, distinguishing it from the behavior observed in single-phase FCC HEAS. This study conducts an in-depth analysis of grain size's impact on the SRS of (Fe50Mn30Co10Cr10)97Al3 dual-phase HEA, scrutinizing micro-level aspects encompassing phase transformation, deformation twinning, and grain boundary slip. The findings provide essential theoretical insights for designing HEAS tailored for applications requiring high strain rates.

Readers Who Read This Article Also Read

Bookmark

Share it with SNS

Article Title

Dependence of mechanical properties and deformation behavior of TRIP-FeMnCoCrAl dual-phase high-entropy alloy on grain size and strain rate

Activity of Iron Oxide in Slag with Nepheline Syenite Added as a Flux

Yusaku Sakamoto, Keijiro Saito, Masakatsu Hasegawa

Abstract

Although fluorspar has been widely used as a flux for steelmaking slag, there is a strong incentive to explore alternatives. As one of the candidates for such substances, "nepheline syenite" has been investigated in terms of slag fluidity and lime dissolution rate. The present study aimed at clarifying the homogeneous liquid region and FexO activities in the CaO-FexO slags with nepheline syenite added at 1673 K. When the molar ratio of nepheline syenite/CaO was below 0.658, the substitution of CaO with nepheline syenite raised the FexO activity as well as CaF2. The effect of the nepheline syenite addition on slag basicity was discussed by means of the reduction-oxidation reaction of Fe3+/Fe2+.

Bookmark

Share it with SNS

Article Title

Activity of Iron Oxide in Slag with Nepheline Syenite Added as a Flux

Effect of rolling and alloying elements on the impact properties of hypereutectoid steels

Toko Tokunaga, Yoritoshi Minamino, Koji Yamamoto, Toshiyuki Sugimoto, Koji Hagihara

Abstract

In this study, to develop steel with high strength and ductility, steels are designed based on JIS-SUJ2 hypereutectoid steel by controlling the contents of the alloying elements Cr and Mn. The steels are subjected to two types of specially designed heat treatment, i.e., "grain boundary amelioration (GBA)" treatment, with and without rolling. The effects of the alloy type and rolling on the microstructure and impact properties are investigated. High impact values over 50 J/cm2 were achieved compared to those of conventional steels by the significant refinement of γ grains with GBA treatment. All the steels exhibit transgranular fracture, and no intergranular fracture was observed. This indicates that the proposed heat treatment achieved the suppression of intergranular fracture by inhibiting the formation of θ particles on the grain boundaries and by refining the prior γ grains. Moreover, it has been suggested that the impact values were strongly affected by the C content in the matrix which is controlled by the alloying element and by the heat treatment. As the C content increases, hardness and fraction of the retained γ phase increase, which leads to the decrease in impact value. In samples where prior γ grains were extremely fine and θ particles were fine, area fraction and circularity of the θ particles did not have a significant effect on the impact values.

Bookmark

Share it with SNS

Article Title

Effect of rolling and alloying elements on the impact properties of hypereutectoid steels

Separation of Phosphorus from Phosphorus-concentrated Steelmaking Slag

Takayuki Iwama, Ryo Inoue, Kenji Nakase, Shigeru Ueda

Abstract

Since 10 million tons of steelmaking slag, which contains a few percent of phosphorus, are annually produced, the phosphorus amount in the slag is equivalent to the annual import volume of phosphorus rock in Japan. Therefore, the steelmaking slag is attracting attention as a potential phosphorus resources. Phosphorus-concentrated slag obtained by the dephosphorization reaction between high phosphorus hot metal and oxidizing slag at high temperature contains phosphorous comparable to that of phosphorus rock. However, because of high FeO concentration, it is difficult to use for phosphorus resources directly. In this work, the effects of pH, acid type and leaching method on the dissolution behavior of phosphorus from P-concentrated slag were investigated. As a result, phosphorus dissolution progressed at lower pH, and was promoted by the addition of citric acid, which is known as a chelate former. When nylon mill pot stirring with citric acid and alumina mill pot stirring with nitric acid were compared to impeller stirring, respectively. By combining nylon mill pot stirring and citrate leachate, phosphorus dissolution was accelerated, because the slag was pulverized during stirring and a formation of insoluble metal-phosphate was inhibited by the formation of complex ion between leached metal cation and citrate. When the slag was leached with alumina mill pot while controlling pH by nitric acid, the phosphorus dissolution ratio lowered since phosphorus ion and aluminum ion, which is supplied by the dissolution of pot and crushing ball during leaching, constructed secondary products with low solubility along with other dissolved ions.

Bookmark

Share it with SNS

Article Title

Separation of Phosphorus from Phosphorus-concentrated Steelmaking Slag

Enhanced impingement characteristics of supersonic oxygen jets on molten bath using a multi-nozzle oxygen lance in a converter

Junyi Hu, Qijia Yang, Shiliang Yang, Hongshi Yu, Hua Wang

Abstract

In the context of supersonic oxygen jets impinging on the bath surface, understanding the gas-bath interaction mechanism is of paramount importance for optimizing lance design in the converter for steelmaking process. This study employs a coupled VOF model and realizable k-ε turbulence model to simulate the gas/metal/slag turbulent flow in a 180t converter for exploring the essential aspects such as cavity, stirring dead zone, slag-metal splash, and kinetic energy distribution. To validate the model reliability, the numerical results are compared with experimental measurement. The results indicate that: the shear stress from the deflected oxygen jet induces surface waves in the cavity, propagating from its edge to the converter wall. The total splashing volume of the metal and the slag is minimal at a nozzle inclination angle of 14°, while the mass ratio of entrained molten iron in the splash is lowest at an inclination angle of 18°. The slag kinetic energy typically accounts for approximately 30% of the total kinetic energy of the bath. Remarkably, the slag layer, equipped with 4 nozzles and an inclination angle of 14°, demonstrates the most efficient utilization of the molten bath stirring energy, constituting an impressive 34.03% of the total kinetic energy. Moreover, a larger characteristic cavity depth expedites local circulation motion while diminishing the overall stirring performance in the bath. These findings provide valuable insights into the behavior of multiple supersonic oxygen jets in the converter, furnishing essential information for process optimization and design in the steelmaking industry.

Bookmark

Share it with SNS

Article Title

Enhanced impingement characteristics of supersonic oxygen jets on molten bath using a multi-nozzle oxygen lance in a converter

Exploring the Relationship Between Fe-rich SFCA and SFCA-III and Their Presence in Sinter Strand and Pot-grate Sinter

Nathan A.S. Webster, Mark I. Pownceby

Abstract

Using the X-ray diffraction (XRD) patterns collected on the products of laboratory furnace experiments performed on a synthetic iron ore sinter mixture with composition 77.36 % Fe2O3. 14.08% CaO, 3.56% SiO2 and 5.00% Al2O3, it is demonstrated that the previously reported Fe-rich SFCA phase has the same crystal structure as triclinic SFCA-III. Therefore, the four principal members of the silico-ferrite of calcium and aluminium (SFCA) family are SFCA, SFCA-I, SFCA-II, and SFCA-III. In addition, using XRD patterns collected for sinter strand and pot-grate sinter samples supplied as part of a sinter analysis round robin the presence of SFCA-III phase in industrial sinter is confirmed for the first time, with important implications for sinter characterisation and research.

Bookmark

Share it with SNS

Article Title

Exploring the Relationship Between Fe-rich SFCA and SFCA-III and Their Presence in Sinter Strand and Pot-grate Sinter

Quantification of changes in lattice defect density in BCC iron during plastic deformation using electrical resistivity measurements

Soichiro Takenaka, Ryohei Takahashi, Kazuhiro Ishikawa, Yoji Miyajima

Abstract

Change in lattice defects density in bcc pure iron due to tensile deformation was quantified by using both electrical resistivity measurements and X-ray diffraction (XRD). As bcc pure irons, ultra-low carbon steel (ULCS) and interstitial free (IF) steel are used as the model specimen. Dislocation density evaluated using Williamson Hall method with XRD shows the saturation with the value of around 3.7×1015 m-2for ULCS and around 1.4×1015 m-2 for IF steel after plastic strain after ~5%. Increase in electrical resistivity was observed with increasing plastic strain. Consequently, increase in vacancy concentration occurs with increasing plastic strain of around 0.3, such as, 2.6×10-5 for ULCS and 3.4×10-5 for IF steel. Additionally, the migration of carbon atoms from grain interior to grain boundary via dislocation might occur at the initial stage of plastic deformation in ULCS.

Bookmark

Share it with SNS

Article Title

Quantification of changes in lattice defect density in BCC iron during plastic deformation using electrical resistivity measurements

Effect of Molybdenum Content on the Hardenability and Precipitation Behaviors of Boron Steel Austenitized at High Temperatures

Kyohei Ishikawa, Masaaki Fujioka, Manabu Hoshino, Jun Takahashi, Ryuichi Homma, Kohsaku Ushioda

Abstract

The effect of molybdenum (Mo) contents on hardenability and precipitation behaviors in Mo-B simultaneously added steels were investigated placing a focus on high austenitizing temperature. The hardenability of 0.5 % Mo - 11 ppm B steel austenitized at 1150°C was decreased compared with that austenitized at 950 °C, whereas 1.0 % Mo - 10 ppm B and 1.5 % Mo - 9 ppm B steels were less affected by high austenitizing temperature than 0.5 % Mo - 11 ppm B steel. The Fe23(C, B)6 precipitation by increasing austenitizing temperature was also revealed to be suppressed in 1.5 % Mo – 9 ppm B steel. These results indicate that the improved effect of the Mo addition on hardenability by retarding the precipitation of Fe23(C, B)6 still appear in B-added steels austenitized at high temperature. Furthermore, Fe23(C, B)6 precipitation start temperature was increased in Mo–B added steels austenitized at 1150 °C. This result implies that non-equilibrium B segregation mechanism during cooling from high austenitizing temperature enhances the amount of segregated B on grain boundaries leading to the promotion of the borides precipitation at high austenitizing temperature region. However, Mo is presumed to fix a part of thermal vacancies as Mo-V complex resulting in the suppression of non-equilibrium B segregation to grain boundaries during cooling, which is speculated to inhibit the Fe23(C, B)6 precipitation. Thus, the effect of Mo-B combined addition on hardenability was presumably maintained even in high austenitizing temperature region.

Bookmark

Share it with SNS

Article Title

Effect of Molybdenum Content on the Hardenability and Precipitation Behaviors of Boron Steel Austenitized at High Temperatures

In-situ laser ultrasonics measurements of ferrite formation during stepped cooling of a 0.1C-2Mn dual phase steel

Nobumasa Hayashi, Mariana C. M. Rodrigues, Matthias Militzer

Abstract

Dual-phase (DP) steels are advanced high-strength steels used in automotive design. To achieve optimal mechanical properties the control of phase transformations during processing is paramount, e.g. for hot-rolled DP steels a desired ferrite fraction is required to form during run-out table cooling. Thus, sensor technologies such as laser ultrasonics (LUS) are of considerable interest that can in-situ monitor ferrite formation. In this study, the ferrite formation kinetics in a laboratory DP steel were measured by LUS during stepped cooling treatments which were designed to simulate the cooling paths on the run-out table in hot strip mills. LUS measurements were first validated with well-established dilatometry measurements during continuous cooling. For the stepped cooling tests, the fractions transformed obtained from the ultrasonic velocity changes agree with the ferrite phase fractions as characterized by ex-situ metallography. Further, the velocity changes are described by the JMAK approach using parameters that are consistent for the austenite-to-ferrite transformation in low-carbon steels.

Bookmark

Share it with SNS

Article Title

In-situ laser ultrasonics measurements of ferrite formation during stepped cooling of a 0.1C-2Mn dual phase steel

Predictive modeling of strip temperature in continuous annealing furnace: An improved optimization algorithm

Hongfei Ding, Hao Shen, Qian Xie

Abstract

Taking full account of the complex mechanism of the continuous annealing furnace (CAF) production process and the difficulty in establishing an accurate mathematical model, this paper adopts a quantum particle swarm optimization (QPSO) algorithm to optimize the parameters of the radial basis function (RBF) neural network which used to predict the model of strip temperature in CAF. Firstly, to improve the accuracy of modeling, the input and output variables of RBF neural network model prediction are determined by analyzing the mechanism model of the heating section of the CAF and the factors affecting the strip temperature. Secondly, due to the trial and error method used for parameter selection in RBF neural network, which results in low work efficiency and difficulty in selecting the optimal value, the QPSO algorithm is introduced to search for the optimal solution. Furthermore, to avoid encountering local optimal issues and improve searching performance, an improved QPSO algorithm that combines the characteristics of generalized opposition-based learning and differential evolution is proposed. Finally, by collecting the production site data of a large-scale CAF, experiments are carried out to verify the effectiveness of the proposed methods.

Bookmark

Share it with SNS

Article Title

Predictive modeling of strip temperature in continuous annealing furnace: An improved optimization algorithm

Interdiffusion of solute elements in the α-Fe phase of the Fe–Cr–Mo and Fe–Cr–Si ternary systems

Dosung Lee, Mariko Tsuyuguchi, Manabu Watanabe, Yaw Wang Chai, Takako Yamashita, Shin Ishikawa, Yoshisato Kimura

Abstract

To understand the interdiffusion of alloying elements in the α-Fe phase of the Fe–Cr–Mo and Fe–Cr–Si ternary systems, interdiffusion coefficients are determined. The main (Feii and Fejj, 𝑖: Cr and 𝑗: Mo or Si in the present study) and cross (Feij and Feji) interdiffusion coefficients in the ternary systems were determined by the Whittle–Green method. From main interdiffusion coefficients in the ternary systems at 1073 K, the average value of FeMoMo was approximately 1.5 times higher than that of FeCrCr in the Fe–Cr–Mo system, while the average value of FeSiSi was 1.8 times higher than that of FeCrCr in the Fe–Cr–Si system. From the FeCrCr values of the ternary systems, Si has an accelerating effect than Mo on Cr diffusion in the α-Fe phase. Increasing the ratio of the Mo to Cr concentration has a suppressing effect on the respective Cr and Mo interdiffusion flux within the α-Fe phase. Increasing the concentration ratio of Mo to Cr suppresses the effect of Mo and Cr on the respective Cr and Mo interdiffusion fluxes within the α-Fe phase. Considering the temperature dependence, the Mo diffusivity is more sensitive than the Cr diffusivity. The cross interdiffusion coefficients, FeCrMo and FeMoCr, are positive and the values are insignificantly different in the Fe–Cr–Mo system, while FeSiCr and FeCrSi were negative. This study is beneficial to understand microstructure evolution in ferritic stainless steels at high temperatures.

Bookmark

Share it with SNS

Article Title

Interdiffusion of solute elements in the α-Fe phase of the Fe–Cr–Mo and Fe–Cr–Si ternary systems

Effects of Alloying Element on Bainitic Transformation in Fe-0.3N Alloy

Mitsutaka Sato, Shota Shimaya, Kazuki Hara, Goro Miyamoto, Tadashi Furuhara

Abstract

The effects of alloying elements on the bainite transformation behaviors were investigated for Fe-0.3N and Fe-0.3N-1M (M: Si, Cr, Mn, Mo) (mass%) alloys. Nitrogen (N) was introduced into austenite by gas nitriding and subsequent isothermal holding were employed at 500°C. Bainitic ferrite starts to form from the austenite grain boundaries in all alloys. Bainite structure changed from nitride-free bainite (B-Ⅰ type) to bainite accompanying film-like nitride precipitation between bainitic ferrite (B-Ⅱ type) with increasing holding time in Fe-0.3N alloy. The transformation kinetics was retarded by addition of all the alloying elements investigated, resulting in larger retained austenite fraction after subsequent cooling to room temperature. The retardation was significant with Cr and Mn addition.

Bookmark

Share it with SNS

Article Title

Effects of Alloying Element on Bainitic Transformation in Fe-0.3N Alloy

Thermodynamic Analysis on Slag/Metal reactions in Steelmaking Process using Direct Reduced Iron and Steel Scraps

Kengo Kato, Hideki Ono

Abstract

Hydrogen reduction processes of iron ores are being developed to achieve carbon neutrality. However, high-grade iron ore pellets used in the current direct reduction process will be depleted in the future. On the other hand, steel scraps recovered from society are usually contaminated with tramp elements, which are difficult to remove in the current steel refining processes. To produce high-quality steel from DRI and steel scraps, molten steel composition in the melting process should be optimized considering the impurities originating in iron resources and conditions such as temperature and oxygen potential. In this study, the equilibrium of slag/metal reactions in the steelmaking process using DRI and steel scraps were thermodynamically analyzed, and the effect of using scrap on the composition of molten steel and slag and the conditions to produce low-phosphorous molten steel from high-P content DRI and steel scrap were discussed. The use of steel scrap showed such advantages as a decrease in the concentrations of Si, S, and P originating from high-P DRI, a decrease in the amount of slag, and a reduction in the amount of limestone required to maintain slag basicity. Moreover, the P content of iron can be decreased to 13 mass ppm at 1873K and 𝑃O2 = 10-10 atm even when the high-P DRI is used in combination with steel scrap. The thermodynamic analysis showed the potential for carbon-free steel by optimizing the hydrogen reduction process and the melting process of DRI with steel scraps.

Bookmark

Share it with SNS

Article Title

Thermodynamic Analysis on Slag/Metal reactions in Steelmaking Process using Direct Reduced Iron and Steel Scraps

RDDPA: Real-time Defect Detection via Pruning Algorithm on Steel Surface

Kun Lu, Xuejuan Pan, Chunfeng Mi, Wenyan Wang, Jun Zhang, Peng Chen, Bing Wang

Abstract

Real-time object detectors deployed on general-purpose graphics processing units (GPUs) or embedded devices allow their mass usage in industrial applications at an affordable cost. However, existing state-of-the-art object detectors are difficult to meet the requirements of high accuracy and low inference latency simultaneously in industrial applications on general-purpose devices. In this work, we propose RDDPA, a fast and accurate defect detection framework. RDDPA adopts a novel end-to-end pruning scheme, which can prune the detection network from scratch and achieve real-time detection on general-purpose devices. Additionally, we have developed a new training scheme to minimize the accuracy loss associated with the pruning process. Experimental results on a standard steel surface defect dataset indicate that our model achieves 79.2% mAP (mean Average Precision) at 103.7 FPS (Frames Per Second) on a single mid-end Titan X GPU as well as 40.1 FPS on a single low-end GTX 960M GPU, and outperforms the state-of-the-art defect detectors by about 20× speedup with considerable or higher accuracy.

Bookmark

Share it with SNS

Article Title

RDDPA: Real-time Defect Detection via Pruning Algorithm on Steel Surface

Influence of Crystal Structure and Chemical Composition on the Reducibility of Silico-Ferrite of Calcium and Aluminum in CO-CO2-H2-H2O atmosphere

Daisuke Maruoka, Shojiro Mataoka, Eiki Kasai, Taichi Murakmi

Abstract

In this study, influence of crystal structure and chemical composition for Silico-Ferrite of Calcium and Aluminum (SFCA) on its reducibility are examined. Eight types of powder samples containing SFCA and SFCA-I were prepared using chemical reagents by the heat treatments in air. The samples were heated up to 800°C in the different atmospheres of CO-CO2-H2-H2O systems. The reducibility of the samples was evaluated using the peak intensity ratio identified by XRD before and during the reduction experiment. The intensity of SFCA peak is not decreased up to 700°C in CO-CO2 atmosphere, whereas the intensity become weak in CO-CO2-H2-H2O atmosphere. The intensity of SFCA-I peak is decreased above 500oC in all atmospheric condition and the reduction reactions are enhanced by the addition of H2-H2O gas. Decrease in intensity of SFCA peak is independent of Fe composition, whereas that of SFCA-I is decreased with decreasing Fe concentration. The difference in reducibility is attributed to the difference in the crystal structure of multi-component CF. SFCA and SFCA-I are composed of pyroxene and spinel units. Since the pyroxene unit contains more gangue minerals than spinel unit, it implies that the pyroxene unit shows low reducibility than the spinel units. Since SFCA-I contains more the spinel units than SFCA, SFCA-I is easily reduced than SFCA.

Bookmark

Share it with SNS

Article Title

Influence of Crystal Structure and Chemical Composition on the Reducibility of Silico-Ferrite of Calcium and Aluminum in CO-CO2-H2-H2O atmosphere

Precipitation behavior of MnS inclusion in unidirectionally-solidified Fe-18Mn-1Al-0.3C steels

Yuewen Fan, Kouki Kameda, Xiaojun Hu, Hiroyuki Matsuura

Abstract

In order to reasonably control the precipitation of inclusions during solidification in TWIP steels, the precipitation behavior of typical MnS inclusions in high manganese steel was investigated by unidirectional solidification experiments. Through the combined analyses using ASEM-EDS, optical microscope, and thermodynamic calculation, it was found that Mn concentration in the liquid metal region were higher than those in the solid metal region. Furthermore, closer to the inclusion the liquid phase was, higher its Mn content was. In Fe-18mass%Mn-1Al-0.3C, MnS inclusions can precipitate at the positions located in the junction of dendrites at the end of the solidification (solid fraction fs=0.96), Mn content reaching 34.88 mass%. Already existing Al2O3 particles could become the core of MnS to form composite inclusions to promote the MnS precipitation during the solidification process. When fs achieved 0.7 leading the Mn segregation in the liquid phase to 25 mass%, MnS starts to precipitate to attach the Al2O3 surface to form composite inclusion.

Bookmark

Share it with SNS

Article Title

Precipitation behavior of MnS inclusion in unidirectionally-solidified Fe-18Mn-1Al-0.3C steels

Local yield stress and its unusual independence on multi-axial stress states during Lüders deformation of medium-Mn, high-strength steel

Takashi Matsuno, Koki Furukawa, Yoshitaka Okitsu, Motomichi Koyama, Toshihiro Tsuchiyama

Abstract

Medium-manganese steel that undergoes Lüders deformation exhibits good uniform elongation owing to large elongation with a yield plateau. To accurately predict the deformation behavior in engineering applications, the yield stresses of medium-manganese steel (5% Mn), exhibiting the transformation-induced plasticity (TRIP) effect were investigated during elongation under a multi-axial stress state (MSS). Compact tensile tests with real-time diameter measurements were conducted on smooth and notched, tiny round-bar specimens to evaluate the local yield stress and strain without the Lüders band propagation effect. Consequently, the true stress plateau was measured without the upper yield point for the smooth round-bar specimen, and the cross-sectional average true stress of the blunt notched round-bar specimens had the same plateau as the smooth round-bar specimen. The sharp-notched round-bar specimen exhibited a two-stage linear increase in true stress. The true stresses of the three specimens at the initial yield point were almost identical. Under the MSS, the hydrostatic stress typically increases the true stress at the initial yield point. The independence of the MSS indicates that the yield stress during elongation was independent of the shear-dominant crystal slip resistance. Finite element (FE) analysis using the Mises yield locus did not express the true stress plateau and its independence of the MSS. Additionally, the transformation rate of retained austenite was measured for mechanistic analysis; however, the TRIP effect did not contribute to this unusual independence because it started at the intermediate yield elongation stage. Thus, the stress criterion for the generation of mobile dislocations can determine yield stress.

Readers Who Read This Article Also Read

Bookmark

Share it with SNS

Article Title

Local yield stress and its unusual independence on multi-axial stress states during Lüders deformation of medium-Mn, high-strength steel

Activity of Chromium Oxide in CaO-SiO2-MgO-Al2O3-MnO-CaF2-CrOx Slag for Chromium Reducing Process

Chonglin Shi, Zhi Li, Yuxing Liu, Yoshinao Kobayashi

Abstract

Thermodynamic data of chromium oxide activities in molten slags are important for improvement of the reduction treatment process of chromium oxides in stainless steel slags. The chemical equilibrium experiments were conducted in the present work to measure the activity coefficients of chromium oxides in the CaO-CaF2-MgO-Al2O3-SiO2-MnO-CrOx slags at 1823 K (1550°C) under oxygen partial pressure of 2.57×10-11 atm with different chromium oxides contents. It is found that no solid phase appears in the slag when the initial CrO1.5 mole fraction of the slag is no more than 0.00390 (0.5 mass%), which could ensure the accuracy of the chromium valence analysis. The activity coefficient of CrO keeps almost constant with the increase of mole fraction of total chromium oxides, which indicates that CrO obeys Henry's law under the present conditions. The activity coefficient of CrO1.5 firstly levels off and then rises sharply when the mole fraction of total chromium oxides reaches 0.00198, beyond this point, activity coefficient of CrO1.5 keeps relatively constant again. Through the Raman spectroscopy analysis, the sharp increase of the activity coefficient of CrO1.5 is assumed to be caused by the transformation of CrO1.5 from network former to network modifier.

Bookmark

Share it with SNS

Article Title

Activity of Chromium Oxide in CaO-SiO2-MgO-Al2O3-MnO-CaF2-CrOx Slag for Chromium Reducing Process

You can use this feature after you logged into the site.
Please click the button below.

Advanced Search

Article Title

Author

Abstract

Journal Title

Year

Please enter the publication date
with Christian era
(4 digits).

Please enter your search criteria.