著者

Hideo Mizukami Yoshihisa Shirai Akira Kawakami Alec Mitchell

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.60, no.11, pp.2455-2461, 2020-11-15 (Released:2020-11-17)

参考文献数

23

被引用文献数

5 12

---

It is important to understand the solidification behavior of titanium alloys for optimizing the casting conditions. In this study, to evaluate the solidification behavior of the Ti-6Al-4V alloy, an experiment was conducted using a lab-scale electron beam furnace. After melting the surface layer of the ingot through electron beam heating, the surface layer was allowed to solidify. Based on the measurement results of the cooling curve of the surface of the ingots, it was observed that the solid was subject to undercooling during its formation. The cooling rate of the ingot could be predicted through numerical simulation, for the melting and solidification of the ingot. The primary and the secondary dendrite arm spacing were examined with respect to the cooling rate. The concentrations of Al and V in the dendritic region were analyzed using electron probe microanalysis (EPMA). It is clarified that the Al is segregated into the dendrite core during solidification, and that V is segregated into the interdendritic region.

著者

Ko-ichiro Ohno Yoshiki Kitamura Sohei Sukenaga Sungo Natsui Takayuki Maeda Kazuya Kunitomo

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.60, no.7, pp.1512-1519, 2020-07-15 (Released:2020-07-16)

参考文献数

11

被引用文献数

5 7

---

Negative effect from low coke rate operation at cohesive zone is obvious because it makes thinning of coke slit thickness. Correct knowledge about gas permeability of cohesive layer is becoming more and more important. In order to precisely understand cohesive behaviour, a softening and melting simulator under rapid heating and quenching conditions was applied for clarify a determinant factor of gas permeability behaviour. To focus on softening and melting behaviour, granulated slag particle bed layer without iron oxide was prepared as packed bed sample layer can show softening and melting. The packed bed slag samples in graphite crucible were rapidly heated up to 1200°C, and then gradually heated up to 1500°C with 10°C/min under inert gas atmosphere and 0.1 MPa load. Gas pressure drop and shrinkage degree of the sample layer were measured during the softening and melting test, and quenched sample was made at certain temperature when the maximum gas pressure drop was measured. The CT observation of the quenched sample provided 3D shape information of gas path shape in sample packed bed. Gas pressure drop was estimated with fanning’s equation with the gas path information. The estimation values were shown positive correlation with measured maximum pressure drop. The CT observation also gave triple line length among molten slag, graphite, and gas. Combination the triple line length and molten slag surface tension could use for evaluation of static force balance when maximum pressure drop obtained.

著者

Manabu Takahashi

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.55, no.1, pp.79-88, 2015-01-15 (Released:2015-02-06)

参考文献数

74

被引用文献数

24 39

---

Development in sheet steels has progressed in strong relation with automotive industry in Japan. To meet the requirements from automotive industry, various types of sheet steels including high and ultra high strength steel sheets have been developed. Progresses in three types of steel series will be discussed by checking the historical facts and technologies and their contributions. Introductions of interstitial free (IF) steel and continuous annealing system are the important events in mild steel developments for panels. Extensive work on finding the optimum mixtures of hard and soft phases to improve elongation of steels contributed to improve the crashworthiness of autobodies. Continuous annealing system also played an important role in producing these advanced high strength steels. Precipitation is used in a particular way which is to scavenge solute carbon and nitrogen and to prevent coarse cementite particle precipitation. It is also worth to point out that the collaborative activities particularly strong in Japan between steel manufacturers and auto companies have affected the progress in advanced sheet steels.

著者

Nobuo Nakada Norimitsu Koga Yuki Tanaka Toshihiro Tsuchiyama Setsuo Takaki Masaharu Ueda

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.55, no.9, pp.2036-2038, 2015-09-15 (Released:2015-09-29)

参考文献数

17

被引用文献数

13 17

---

The strength of pearlitic steel was clearly reduced by annealing, even though cementite stably maintained a lamellar structure. In response, lattice strain of the ferrite phase in pearlite monotonically decreased with increasing annealing time. As a result, a good linear relationship was established between the strength and ferrite lattice strain independent of the interlamellar spacing and morphology of cementite. This suggests that the ferrite/cementite elastic misfit strain contributes to the high strength of pearlitic steel.

著者

Xianfeng Hu Lena Sundqvist Ökvist Elin Åström Fredrik Forsberg Paolo Checchia Germano Bonomi Irene Calliari Piero Calvini Antonietta Donzella Eros Faraci Franco Gonella Joel Klinger Davide Pagano Andrea Rigoni Pietro Zanuttigh Paolo Ronchese Michele Urbani Sara Vanini Aldo Zenoni Gianni Zumerle

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.58, no.1, pp.35-42, 2018-01-15 (Released:2018-01-17)

参考文献数

17

被引用文献数

3 7

---

Knowing the distribution of the materials in the blast furnace (BF) is believed to be of great interest for BF operation and process optimization. In this paper calibration samples (ferrous pellets and coke) and samples from LKAB’s experimental blast furnace (probe samples, excavation samples and core-drilling samples) were measured by the muon scattering tomography detector to explore the capability of using the muon scattering tomography to image the components in the blast furnace. The experimental results show that it is possible to use this technique to discriminate the ferrous pellets from the coke and it is also shown that the measured linear scattering densities (LSD) linearly correlate with the bulk densities of the measured materials. By applying the Stovall’s model a correlation among the LSD values, the bulk densities and the components of the materials in the probe samples and excavation samples was established. The theoretical analysis indicates that it is potential to use the present muon scattering tomography technique to image the components in various zones of the blast furnace.

著者

Nobuo Nakada Norihide Fukuzawa Toshihiro Tsuchiyama Setsuo Takaki Tamotsu Koyano Takashi Iwamoto Yasuhiro Omori

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.53, no.1, pp.139-144, 2013 (Released:2013-01-15)

参考文献数

22

被引用文献数

10 13

---

In order to understand the mechanism of isothermal transformation of Fe–N alloy, the isothermal transformation microstructure that forms in a wide temperature range below Ae1 was investigated in Fe–2.6 mass%N hypereutectoid alloy by means of the electron back scatter diffraction method in addition to the conventional microstructural observation methods. High-nitrogen austenite fully decomposed to ferrite and Fe4N over the entire temperature range, and the time-temperature-transformation (TTT) diagram had a C shape with a nose temperature around 700 K. The hardness linearly increased with decreasing transformation temperature because the microstructure became finer, but the morphology of the (ferrite + Fe4N) structure changed discontinuously at around 800 K. From the microstructural and crystallographic analyses, it was concluded that the microstructure formed at higher temperature is a lamellar eutectoid structure, braunite, while the other is an upper bainitic structure containing bainitic ferrite formed through a displacive mechanism and Fe4N formed by concentration and ordering of the nitrogen. Since Fe4N is a counterpart of the cementite in Fe–C alloy, the respective structures are similar to pearlite and upper bainite in carbon steel.

著者

C. E. LOO

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.45, no.4, pp.436-448, 2005 (Released:2006-01-27)

参考文献数

45

被引用文献数

48 62

---

The main purpose of iron ore sintering is to produce a strong agglomerate for the blast furnace. This is achieved by partially melting a sinter mix at high temperature and then allowing the melt to solidify into a bonding phase for the unreacted material. The melt formation and subsequent solidification processes are highly dependent on the composition of the blended mix. This paper summarises the differences in sintering behaviour between hematite ores and goethitic ores based on past research programs carried out at BHP Billiton. From a fundamental evaluation of the sintering process, it is clear that productivity can be an issue with goethitic ores because of their low bulk density and high porosity. This paper recommends steps towards overcoming losses in productivity. The effect of goethitic ores on coke rates is also a matter of general concern and this study shows that the addition energy required to dehydrate goethites and remove the additional water introduced into the system is comparatively small. The properties of melts have been shown to be particularly important in determining yield from a sinter machine and it is evident that the easy-melting properties of goethitic ores will also have an impact on this area. This paper also reviews our current understanding of how goethitic ores can influence sinter quality. The implication of fundamental knowledge on practical sinter plant operation is discussed throughout and collated at the end of the paper.

著者

Yasuko Furunushi Kazuhiro Nagata

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.54, no.5, pp.1074-1079, 2014-05-15 (Released:2014-06-12)

参考文献数

10

被引用文献数

2 6

---

Ancient Japanese low-carbon steel, called “Hocho-tetsu” or “Wari-tetsu”, was made in “Okaji” process by decarburizing pig iron named “Zuku” produced in “Tatara” process. It is known that the low-carbon steel had higher corrosion-resistance and was much easier to forge-and-weld than modern steel. Japanese iron nails, called “Wakugi”, were made from “Hocho-tetsu” and had been used in shrines and temples until the Meiji period. The low carbon steel tends rapidly to make thin film of magnetite, called “Kurosabi”, on the surface to protect against corrosion under wet atmosphere or heating. The magnetite film is produced from the reaction of iron and oxygen. The oxygen and carbon concentrations in the iron matrix of ferrite in “Wakugi” were measured using EPMA to be about 0.15 to 0.38 mass% and 0.02 mass%, respectively. The oxygen concentration is over-saturated from the oxygen solubility of αFe and γFe. The over-saturated concentration of oxygen in “Wakugi” was caused from “Okaji” process without deoxidation of steel.

著者

Jan Bohacek Abdellah Kharicha Andreas Ludwig Menghuai Wu

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.54, no.2, pp.266-274, 2014-02-15 (Released:2014-03-11)

参考文献数

26

被引用文献数

11 15

---

In order to simulate the mold filling and solidification of the outer shell of large work rolls being cast by horizontal centrifugal casting, the shallow water equations were adopted to solve the 2D average flow dynamics of the melt spreading inside the cylindrical mold. The model accounts for centrifugal force, Coriolis force, shear force, gravity and convective and diffusive energy transport. The solidification front was tracked by fulfilling the Stefan condition. Radiative and convective heat losses were included from both, the free surface and the outer wall of the mold. By introducing a stochastic factor to account for the irregular filling jet behavior an uneven spreading of liquid from the center of the mold towards the extremities was predicted. Thus, the formation of the first solid layer also happens unevenly. However, when the mold is covered everywhere with a solid layer, the solidification rate decreases and further filling increases the height of the liquid layer. With increase liquid height the amplitude of the free surface waves also increases.

著者

Reon Ando Takashi Matsuno Tomoko Matsuda Norio Yamashita Hideo Yokota Kenta Goto Ikumu Watanabe

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.61, no.1, pp.473-480, 2021-01-15 (Released:2021-01-16)

参考文献数

21

被引用文献数

3

---

Herein, we investigated the local preliminary hardening of ferrite near the ferrite–martensite interfaces in a dual-phase (DP) steel. Geometrically necessary dislocations (GNDs), generated due to interfacial misfit between different phases, may cause preliminary hardening of ferrite around such interfaces. However, for nano-hardness distribution, the hardened zone was not evidently detected by scattering measurement. Thus, we factorized nano-hardness scattering to estimate the actual ferrite hardness near ferrite–martensite interfaces.First, nano-hardness was measured around a martensite island using a conical nano-indenter in the DP steel containing 10% martensite by volume. Taking into account the scattering, the nano-hardness measurement converged to the hardness of ferrite, exceeding the distance corresponding to the nano-indenter radius. Thus, a preliminary hardening zone was not detected. Subsequently, the surface of the nano-indented microstructure was polished and observed using scanning electron microscopy (SEM) by analyzing electron back scattering diffraction (EBSD). This analysis confirmed the presence of the nano-indented microstructure under ferrite. Moreover, it established that the majority of the irregularly higher nano-hardness was caused by the buried martensite under ferrite. The value of the kernel average misorientation (KAM), which is proportional to the GND density for other irregularly higher nano-hardness points, was higher for the nano-indented microstructure as compared to that of the buried martensite. On the other hand, the ferrite was expanded under the nano-indented points for the majority of the irregularly lower nano-hardness, with some exceptions. Further, soft martensite was observed to induce irregularly lower nano-hardness locally around the interface.

著者

Toshiyuki Hirosawa Akinori Murao Nobuyuki Oyama Shiro Watakabe Michitaka Sato

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.55, no.6, pp.1321-1326, 2015-06-15 (Released:2015-06-20)

参考文献数

12

被引用文献数

4 6

---

The use of high reactivity coke is a technology that dramatically improves the reaction efficiency in blast furnaces by decreasing the temperature of the thermal reserve zone. In this study, a blast furnace shaft simulator was developed to estimate the temperature of the thermal reserve zone and the distributions of the temperature and gas composition in the blast furnace when using cokes with different reactivity. The shaft simulator combines an experimental reaction furnace and a calculation model. Chemical reaction and mass/heat transfer phenomena in the blast furnace are considered in the calculation model so as to calculate the ore and coke reaction rate and the distribution of temperature and gas composition. Relatively small amounts of packed coke and sinter specimens are reacted with the temperature and gas composition controlled based on the calculation results. The coke gasification rate is fed back to the calculation model, and it is then possible to estimate the temperature of the thermal reserve zone and the distributions of the temperature and gas composition in the blast furnace. Shaft simulator experiments with high reactivity coke, such as CIC (Carbon Iron Composite), showed that the temperature of the thermal reserve zone is 140 K lower with high reactivity coke than with conventional coke.

著者

Yusuke Kashihara Yuki Iwai Natsuo Ishiwata Nobuyuki Oyama Hidetoshi Matsuno Hiroyuki Horikoshi Koji Yamamoto Minoru Kuwabara

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.57, no.4, pp.665-672, 2017-04-15 (Released:2017-04-19)

参考文献数

29

被引用文献数

4 6

---

Improved permeability and increased gas utilization have been desired in order to achieve low coke rate operation of blast furnaces. Coke mixed charging in the ore layer is one of the effective measures for realizing these improvements. A new charging technique for mixing small coke in the ore layer at a blast furnace with a center feed type bell-less top was developed and investigated in an experiment with a 1/18.8 scale model of an actual blast furnace at JFE Steel. By the new charging technique that small coke was charged in the determined port of the upper bunker before ore was charged in the upper bunker, the discharge pattern of the mixed small coke discharged from the bell-less top was improved, and the radial distribution of the mixed small coke ratio at the furnace top after the mixed materials were charged in the blast furnace was also improved. The new charging technique was applied to an actual blast furnace at JFE Steel, and improvement of gas permeability and a decrease in the coke rate were confirmed.

著者

Kazuhira Ichikawa Yusuke Kashihara Nobuyuki Oyama Toshiyuki Hirosawa Jun Ishii Michitaka Sato Hidetoshi Matsuno

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.57, no.2, pp.254-261, 2017-02-15 (Released:2017-02-16)

参考文献数

22

被引用文献数

11 14

---

Recently, low coke rate blast furnace operation has been required in response to the rising cost of coking coal. However, the thickness of the coke layer decreases in low coke rate operation. Since it is known that the gas permeability of the blast furnace deteriorates as the coke layer thickness decreases, it is important to determine the minimum coke layer thickness for stable blast furnace operation. On the other hand, the minimum coke layer thickness has not been clarified due to a lack of equipment capable of measuring the effect of the coke layer thickness on permeability.In this study, a new experimental device called the cohesive zone simulator was developed to clarify the minimum coke layer thickness. In the cohesive zone, gas flows horizontally along the coke layer. In order to quantify the effect of the coke layer thickness on permeability, this horizontal gas flow should be simulated. Therefore, this simulator simulates a horizontal gas flow.Next, the effect of the coke layer thickness was quantified by using the cohesive zone simulator. The results showed that melting iron ore penetrated into the coke layer and closed part of the layer. These phenomena caused a deterioration of permeability under thin coke layer thickness conditions.Finally, a pressure drop estimation model considering penetration of the coke layer by melting ore was developed with the aim of quantifying the minimum coke slit thickness.

著者

Naoyuki Takeuchi Yuji Iwami Takahide Higuchi Koichi Nushiro Nobuyuki Oyama Michitaka Sato

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.54, no.4, pp.791-800, 2014-04-15 (Released:2014-06-05)

参考文献数

31

被引用文献数

11 16

---

In the recent operation of blast furnace, it is supposed that high gas permeability of burden is important for low RAR and high PCR operation. In this work, sinter quality for improvement in gas permeability of blast furnace was investigated with reduction degradation and under-load-reduction tests. As the results, the reduction degradation of sinter is deteriorated by increasing H2 concentration in the reduction gas under the condition of below 3.8 vol% H2. However, over 3.8 vol% H2, increase of H2 has no effect on the reduction degradation because the diffusion of reduction gas in the sinter is limited. On the other hand, from the under-load-reduction test, there is possibility that increase in H2 concentration of reduction gas and decrease in slag ratio in sinter are effective to improve gas permeability of lower part of blast furnace rather than reducibility of sinter. Due to adoption of these experimental results to a 2-dimentional mathematical simulation model, the precision of pressure drop calculation of blast furnace was improved. It is considered from the evaluation by this model calculation that the RDI, a slag ratio and the slag viscosity as the sinter properties are greatly influence on the permeability of blast furnace.

著者

Hirokazu Natsumeda Amane Kitahara Shunichi Hashimoto

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.57, no.5, pp.945-952, 2017-05-15 (Released:2017-05-16)

参考文献数

32

被引用文献数

3 6

---

Recently, 5% Mn steel has been focused on as one of the promising candidates for third generation AHSS by showing an excellent TS (Tensile Strength)-El (Elongation) relationship. The excellent TS-El relationship is brought about by a large volume fraction of retained austenite through the enrichment of austenite stabilizing elements such as C and Mn in retained austenite. The effect of the microstructure of mother hot band on the changes in microstructure and mechanical properties was compared with the intercritical annealing time in this study. The steel containing about 10% of retained austenite in a mother hot band exhibited a higher volume fraction of retained austenite and higher strength after intercritical annealing. On the other hand, the steel which did not contain retained austenite in a mother hot band exhibited excellent TS-El combination. The difference of work hardening behavior in these steels was analyzed and thought to be brought about by the difference of transformation behavior during deformation determined by the stability of retained austenite affected by Mn concentration. Although the precipitation of cementite was intended to effectively act as a nucleus of reverted austenite formation and to accelerate its formation, this affirmative result was not obtained. Since the volume fraction of cementite in a short annealing time is nearly the same in all hot rolling conditions, the higher volume fraction in hot band did not act to increase retained austenite during intercritical annealing.

著者

Abbas Mohammadi Motomichi Koyama Gregory Gerstein Hans Jürgen Maier Hiroshi Noguchi

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

pp.ISIJINT-2019-510, (Released:2020-05-25)

参考文献数

42

被引用文献数

4

---

Hydrogen-assisted crack growth of pre-strained twinning-induced plasticity (TWIP) steel was investigated using artificial defects (micro-drilled holes), which acted as artificial crack initiation sites. Hydrogen was introduced into the specimens by electrochemical hydrogen charging during slow strain rate tensile test. The quasi-cleavage crack propagation observed was due to repeated crack initiation near the crack tip and subsequent coalescence. Crack initiation near the crack tip occurred after plastic deformation of the crack tip, and pre-straining facilitated plasticity-driven crack initiation. The early stage of plasticity-driven crack growth was sensitive to the crack length and remote stress level. Accordingly, the crack growth rate in the early stage increased with the increase in the initial defect size. In the following stage of the crack growth, the crack growth rate exhibited a complicated trend with respect to the crack length, which is possibly due to the plastic-wake-altered stress field around the crack tip, which depends on the initial defect size.

著者

Masahiro KAWAKAMI Takahiro KARATO Toshihide TAKENAKA Seiji YOKOYAMA

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.45, no.7, pp.1027-1034, 2005 (Released:2006-01-27)

参考文献数

15

被引用文献数

58 82

---

In order to discuss the reactivity of carbonaceous materials with CO2, the Raman spectroscopy analysis was carried out. Nine kinds of materials were examined. The Raman spectra of ordered materials could be assigned to the graphite structure and its defect, but those of disordered materials could not. New parameters were derived to evaluate the structure of the latter. Using the parameters, the structure change was followed during high temperature heat treatment. The disordered material consists of random structure, graphite structure and its defects. The random structure changes to the graphite structure with many defects and the defects decrease with the heat treatment temperature. The reaction rate constant is evaluated. It increases when the structure changes from the random structure to the graphite structure with many defects. After the change, it decreases with decreasing the defects in graphite structure. Thus, the most reactive material should consist of the graphite structure with many defects.

著者

Masahiro Yakeya Akito Kasai Rikizo Tadai Kentaro Nozawa

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.60, no.7, pp.1438-1444, 2020-07-15 (Released:2020-07-16)

参考文献数

20

被引用文献数

7

---

A major operational problem in increasing pulverized coal rate and decreasing coke rate must be the increased pressure drop or the worsened gas permeability at the lower part of the blast furnace. In order to decrease the pressure drop at the blast furnace cohesive zone (CZ) under low coke rate operation, this study has focused on mixed coke charging in the ore layer. Results obtained by numerical analysis and experiments are as follows:(1) Numerical analysis using DEM (Discrete Element Method) clarified the change in the cohesive ore bed structure with mixed coke charging and the formation conditions of gas path in the bed. Also, DEM-CFD (DEM and Computational Fluid Dynamics) analysis enabled us to find a gas permeability improvement mechanism and an optimum coke mixing ratio for different CZ conditions before applying the technology.(2) Experiments in blast furnace hot model demonstrated the decreased pressure drop at the CZ by mixed coke charging in the ore layer. The experimental results abided by the numerical analysis results.

著者

Jei-Pil Wang W. D. Cho

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.49, no.12, pp.1926-1931, 2009-12-15 (Released:2009-12-20)

参考文献数

15

被引用文献数

12 26

---

The oxidation of pure copper in oxygen with and without water vapor was investigated as a function of temperature, oxygen pressure, and water vapor pressure using thermogravimetric analysis. The rate of the oxidation was increased with increasing temperature from 500 to 700°C and followed by the parabolic rate law regardless of the presence of water vapor. The activation energy for the oxidation was 90.67 kJ/mol in dry oxygen and 95.86 kJ/mol in oxygen with water vapor. The change of oxygen pressure without water vapor does not affect the oxidation rate at given temperatures. However, increasing water vapor pressure from 0.39 to 0.58 atm resulted in higher oxidation rate due to the increase of copper vacancies. CuO whiskers were observed and their growth seems to be enhanced by the presence of water vapor.

著者

Yanbin Yin Jiongming Zhang Shaowu Lei Qipeng Dong

出版者

The Iron and Steel Institute of Japan

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

pp.ISIJINT-2017-347, (Released:2017-10-13)

参考文献数

41

被引用文献数

2 40

---

Large inclusions captured by the solidifying shell deteriorate the surface quality of interstitial free steel. To investigate the capture of large inclusion in slab continuous casting, a three-dimensional model coupling flow field, solidification and inclusion motion has been developed. Additionally, to study the effect of in-mold electromagnetic stirring (M-EMS) on large inclusion capture, the electromagnetic field has been also coupled in the model. The results of electromagnetic field indicates its centrally symmetrical distribution on the cross-section, and the electromagnetic force swirls on the cross-section. The effects of M-EMS on flow pattern, solidification and inclusion capture have been discussed. The M-EMS significantly changes the flow pattern and solidifying shell thickness. The inhomogeneous distribution of large inclusions existing in the slab surface in the slab surface are different between the cases with and without M-EMS. Furthermore, the number of captured inclusions increases at 0–0.02 m beneath the wide surface and decreases at 0.02–0.04 m beneath the wide surface in response to the application of M-EMS. Large inclusions in steel were quantitatively analyzed by the galvanostatic electrolysis method. The experimental results are in agreement with the simulation results, suggesting that the model is valid.