著者

大塚 秀幸 V.A. Dinh 大野 隆央 津﨑 兼彰 土谷 浩一 佐原 亮二 北澤 英明 中村 照美

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.100, no.10, pp.1329-1338, 2014 (Released:2014-09-30)

参考文献数

22

被引用文献数

10

---

The effects of carbon content on tetragonality and magnetic moment of bcc iron have been evaluated by first-principles calculation. Three kinds of supercells, Fe54C1, Fe54C2 and Fe128C1 (which correspond to Fe-0.40C, Fe-0.79 and Fe-0.17C mass%, respectively) are used for the calculation of tetragonality and magnetic moment of Fe-C system. Main results obtained are as follows. (1) The total energy and mechanical energy of the Fe-C system with carbon atom at the octahedral sites are smaller than those with carbon atom at the tetragonal sites. The carbon atom at octahedral site produces fairly large expansion in one direction. (2) Tetragonality of Fe-C system obtained by first-principles calculation increases linearly with increasing carbon content and agrees well with experimental results. The average magnetic moment of an Fe atom increases with increasing carbon content. (3) The magnetic moment of an Fe atom at the nearest neighbor of carbon atom is lower than that of pure iron and increases with increasing distance between the iron and carbon atoms. The projected density of states shows a hybridization with main contributions from Fe d and C p states which leads to the above mentioned decrease of the magnetic moment of an Fe atom. (4) In Fe54C2, tetragonality and magnetic moment of iron atom change with the distance between two carbon atoms. The value of tetragonality is either 0.981, 1.036 or 1.090. When the dumbbell structure which consists of the first carbon atom and its two nearest neighbor iron atoms is perpendicular to the second dumbbell structure which consists of the second carbon atom and its two nearest neighbor iron atoms, the tetragonality is 0.981 and does not agree with experimental value. The mechanical energy is relatively large. On the other hand, when the first dumbbell structure is parallel to the second dumbbell structure, the tetragonality is 1.036 which agrees well with experimental data. The mechanical energy is relatively small. When straight C-Fe-C pair is formed, tetragonality is 1.090. (5) In Fe54C2, formation enthalpy is relatively low when the calculated tetragonality is 1.036, and the existence probability under the assumption of Boltzmann distribution is high. In other cases, the existence probability is nearly zero. (6) The average magnetic moment of an Fe atom is proportional to volume, but not in a clear relation with tetragonality. It is considered that the increase of magnetic moment of an Fe atom by the addition of carbon atom is mainly due to the magneto-volume effect but not due to the tetragonality effect.

著者

滝本 正

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.70, no.10, pp.1348-1356, 1984-08-01 (Released:2009-06-30)

参考文献数

17

被引用文献数

12

著者

工藤 純一 八木 順一郎

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.73, no.15, pp.2020-2027, 1987-11-01 (Released:2010-01-19)

参考文献数

26

被引用文献数

8

---

An attempt was made on the simultaneous analysis of the gas flow and heat transfer in the blast furnace by a mathematical model which considered complex structure and nonuniform sink and source terms for both heat and mass. ERGUN'S equation was used for the equation of motion of gas and potential flow approximation was used for the equation of solid flow. Two dimensional distribution for the velocities of gas and solid was obtained numerically by applying the finite element method with quadratic elements. Fundamental equations of heat transfer on gas and solids were composed of the terms for convection, heat exchange and heat source. Numerical computation of the fundamental equations was carried out in accordance with the method of characteristics. In this analysis, sink and source terms regarding fusion of ore in the cohesive zone and combustion of coke in the raceway were incorporated in the mathematical model as well as radial distributions of particle size and void fraction. It was consequently found that the temperature distribution was affected principally by nonuniform gas flow and thermal flow ratio. Within the cohesive zone, strong consumption of heat by fusion of ore and decrease in the solids velocity appeared. These phenomena affected significantly the temperature distribution in the lower region of the blast furnace together with the generation of heat in the raceway region.

著者

Takehiko TOH Hideaki YAMAMURA Hiroyuki KONDOH Masamitsu WAKOH Eiichi TAKEUCHI

出版者

一般社団法人 日本鉄鋼協会

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.45, no.7, pp.984-990, 2005 (Released:2006-01-27)

参考文献数

14

被引用文献数

4 8 4

---

Fusion of metals in a cold crucible is known as a clean melting method without contamination by refractory. For this reason, it is commonly applied to the fusion of high melting point metals or reactive materials. As the usage of the clean melting function, this technique is also applied to the cleanliness assessment method as an advanced technique of electron beam melting method.In this paper, oxide inclusions behavior in a cold crucible levitation melting of steel is discussed through fundamental experiments and numerical simulations in order to clarify the inclusions behavior during the fusion. Experiments showed a rapid removal of oxides from the bulk molten metal to the sample surface without remarkable change in shape and size distribution of contained oxides. Numerical analyses revealed the dominant factors of this phenomenon, and explained the reason why the size distribution of oxides does not change during the fusion.

著者

朝倉 健太郎 柴田 浩司 原澤 進 澤幡 浩之 川手 稔

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.89, no.3, pp.375-380, 2003-03-01 (Released:2010-01-15)

参考文献数

3

被引用文献数

2

---

Alpha-particle track etching (ATE) method is widely used for the observation of boron distribution in steels. In this method, cellulose films are essential. The cellulose film named CN85 has been used in almost all boron observations by ATE method as a standard film. Recently, however, the production of this film was stopped and the stock seems to be almost exhausted. Therefore, finding the alternative films is urgently required. For this reason, in the present research, the quality of the ATE image, the activation by neutron irradiation and other properties of various kinds of films were examined and the following results were obtained. Industrial nitrocellulose (INC-2 and INC-3) films preprocessed in a lithium nitric acid showed suitable ATE images and can be recommended as the first candidate for the alternative film. Another industrial nitrocellulose (INC-4) film shows acceptable ATE images without any pre-process or pre-heat treatment for surface modification. But after the irradiation of neutron this film becomes radioactive through the generation of 60Co. Therefore, it is necessary to handle this film in a hot laboratory as an activation material. Acetyl cellulose and cellulose triacetate films are the third candidate of the new recommendable film and the ATE images are inferior compared with the nitrocellulose films above mentioned.

著者

八木澤 猛

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.74, no.9, pp.1721-1726, 1988-09-01 (Released:2009-05-29)

参考文献数

20

著者

山田 克美 井上 亮

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.100, no.7, pp.867-872, 2014 (Released:2014-06-30)

参考文献数

47

被引用文献数

3

---

Metallic materials as represented by steels mostly contain various precipitates such as nitrides, carbides and inter-metallic compounds in addition to non-metallic inclusions, oxides and sulfides. These are present as an inevitable former or by design. Those varieties, size and distribution types are very wide then one of important structural factors that affects on various properties of materials.Therefore, accurate analysis of them is considerable significance to control target properties of materials reproducibly. In the steel research field, study of analytical methods for inclusion in steels has been actively conducting since 1960’s. Especially in chemical analysis method, systematization and standardization like JIS has been promoted by corroborated researches in an ISIJ. Previously established methods and detail of analysis of chemical states have been described in publications edited by ISIJ and comprehensive review paper has been issued by Takayama. In this short article, direct observation methods with microscopy, rapid analysis categorized as instrumental analyses, non-destructive inspections and extraction method for non-metallic inclusions are briefly reviewed.

著者

醍醐 市朗 後藤 芳一

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.100, no.6, pp.756-760, 2014 (Released:2014-05-31)

参考文献数

14

被引用文献数

1 7

---

In this study, a random sample of 107 steel bars from Japan and 26 steel bars from China were studied. Each specimen’s elemental composition of tramp elements, such as Cu, Cr, Ni, and Sn, was analyzed. By using the compositions of specific tramp elements, 99 of the 107 samples and 16 of the 26 samples were recognized as electric arc furnace steel. The distributions of the tramp element composition were obtained for the Japanese steel bars and represent a larger number of samples than previous studies. Those for the Chinese samples are the first published data. The compositions of Cu, Cr, Ni, and Sn in the Japanese bars are statistically significantly higher than those in the Chinese bars. Owing to the large gap between the Cu contents of the Japanese and Chinese samples, and the statistically significantly differences between the ratios of Cu to both Ni and Cr in the Japanese and Chinese samples, it is highly likely that copper-based materials are separated from steel scrap at a higher rate in China. The relationship between the Cu and Cr compositions suggested that the mixing of copper-based materials and special steels, which contribute to Cr contamination, differs between Japan and China. The distributions of the Cr composition for each country had larger standard deviations than the distributions of other elements. The ratio of the Cr and Ni compositions in the Chinese samples is less than 2.25, resulting in 18% Cr and 8% Ni in stainless steel. It was found that Ni from materials other than stainless steel was likely to have been included.

著者

Walter NICODEMI Carlo MAPELLI Roberto VENTURINI Riccardo RIVA

出版者

一般社団法人 日本鉄鋼協会

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.45, no.9, pp.1358-1367, 2005 (Released:2006-01-27)

参考文献数

16

被引用文献数

6 8 6

---

This study aims at casting new light about the knowledge of the metallurgical techniques developed by the Etruscan and the Romans during their political and cultural interactions in Central Italy. The analysis of two weapons found at the Etruscan sites of Vetulonia and Chiusi have pointed out some new information about the production process performed. The optical microscopy analysis has allowed to identify the sequence of the microstructural constituents present in the two ancient weapons. SEM-EDS has permitted to identify the chemical composition of the non metallic inclusion and to estimate the average temperature of the reduction process. The analysis of the metal matrix performed by a coupled argon plasma spectrometer permitted to measure the average chemical compositions of the studied alloys. SEM-EBSD analysis has allowed to identify the crystallographic textures present within the different zones of the sword blades and this has indicated the realization of a forming process that gave interesting mechanical properties to the metal products. The results obtained by the Etruscans artisans were of very high standard quality and their production system had been certainly assimilated by the Romans who found in them a strategic factor to increase their power.

著者

松永 久 富永 忠男 王寺 睦満 田中 英夫

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.63, no.13, pp.1945-1952, 1977-11-01 (Released:2010-02-22)

参考文献数

36

被引用文献数

1

著者

長井 健介 篠原 康浩 津留 英司 石野 まゆ子 鈴木 徹也

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.98, no.6, pp.267-274, 2012 (Released:2012-05-31)

参考文献数

16

被引用文献数

1 3

---

It has been well known that anisotropy in yield stress and the work-hardening rate is induced by pre-strain and aging. However, such an origin has not been adequately understood. In the present study, stress-strain curves in different directions were investigated after 2% pre-straining and post-heat treatment at 150°C in ferritic steel. When the applied strain path was changed to the orthogonal direction of the pre-straining path, the re-yield stress was lowered and the work-hardening rate in the low plastic strain was increased. The heat treatment following 2% pre-straining caused an increase of the re-yield stress in the parallel direction to the pre-strain and caused no change on the re-yield stress in the orthogonal direction. The work-hardening rate was increased in both directions after the heating. Electron back scatter diffraction pattern (EBSP) analysis was also conducted to measure the kernel average misorientation (KAM) value, which corresponded to the density of the geometrically necessary dislocation, on each [hkl]-oriented family grain for the pre-strained and the post-heated materials. The EBSP results indicated that heterogeneous work-hardening behavior among the [hkl]-oriented family grains could strongly effect the anisotropy induced by strain path change and aging.

著者

江見 俊彦

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.100, no.1, pp.31-58, 2014 (Released:2013-12-31)

参考文献数

87

被引用文献数

2 13

---

Progress of steelmaking technology in Japan over the last 100 years is reviewed covering hot metal treatment, primary steelmaking with open hearth furnaces, converters and electric arc furnaces, secondary refining of steel with degassers and ladle furnaces, and ingot-/continuous-casting.Key issues that contributed considerably to the progress of the unit processes are highlighted with scientific, technological and engineering breakthroughs involved. Systematization of the unit processes, that optimized full cost, productivity and quality of steel products to meet the constraints on the resources and socioeconomic demands of the steel market at times, is depicted as another key issue for the successful systematization.Possible future development of steel technology is briefly commented on the basis of the above observation.

著者

長谷川 正義

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.57, no.14, pp.2169-2170, 1971-12-01 (Released:2010-10-12)

著者

Gregory Poole Nagy El-kaddah

出版者

一般社団法人 日本鉄鋼協会

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.54, no.2, pp.321-327, 2014-02-15 (Released:2014-03-11)

参考文献数

34

被引用文献数

2 12

---

This paper examines the role of induction coil design on stirring of molten metal in electromagnetic (EM) solidification processes. A model is presented to describe the EM, heat transfer, and fluid flow phenomena in these processes. It is based on a dual-zone description of the mushy region, and accounts for damping of turbulence by the solidified crystallites. The electromagnetic field equations were solved using the mutual inductance technique, while the temperature and turbulent flow fields were calculated using the control volume method. Calculations were performed for solidification of an Al–Cu alloy placed in a stationary magnetic field generated by an induction coil. The effect of coil design on the flow structure was investigated for three different coil positions. It was found that changing the coil position significantly alters the flow pattern from four recirculating loops when the coil is above the midsection of the melt to two loops, typical of a travelling magnetic field, when the coil is at the base of the melt. This significantly modifies the rate of solidification across the ingot, as well as the temperature gradient, in the mushy region. The decay of the velocity and turbulent fields in the mushy region was found to be exponential, with the maximum rate of decay at the solidification front. These results indicate that through changes in coil design, it is possible to control the flow characteristics and solidification behavior in the molten metal.

著者

Tomohiro Takaki

出版者

一般社団法人 日本鉄鋼協会

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.54, no.2, pp.437-444, 2014-02-15 (Released:2014-03-11)

参考文献数

200

被引用文献数

18 162 32

---

The phase-field method has recently emerged as the most powerful computational tool for simulating complicated dendrite growth. However, these simulations are still limited to two-dimensional or small three-dimensional spaces; therefore, to realistic and practical dendritic structures, it is crucial to develop a large-scale phase-field simulation technique. This review discusses the phase-field modeling and simulations of dendrite growth from the fundamental model to cutting-edge very-large-scale simulations. First, phase-field models for the dendrite growth of pure materials and binary alloys and their histories are summarized. Then, models and studies of interface anisotropy, polycrystalline solidification, and solidification with convection, which are very important in dendritic solidification, are reviewed. Finally, by introducing very-large-scale phase-field simulations performed recently using a graphics processing unit supercomputer, the power, potential and importance of the very-large-scale phase-field simulation are emphasized.

著者

吉川 晴十

出版者

一般社団法人 日本鉄鋼協会

雑誌

鐵と鋼 (ISSN:00211575)

巻号頁・発行日

vol.10, no.2, pp.69-124, 1924-02-25 (Released:2009-07-09)

著者

丸山 公一 中村 純也 吉見 享祐

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.100, no.3, pp.414-420, 2014 (Released:2014-02-28)

参考文献数

22

被引用文献数

2

---

Conventional time-temperature-parameter (TTP) methods often overestimate long-term creep rupture life of high Cr ferritic steels. The cause of the overestimation is examined paying attention to temperature and stress dependence of creep rupture life of Gr.91, 92 and 122 steels. In stress-rupture data of all the three steels there are four regions with different values of stress exponent n for rupture life. Activation energies Q for rupture life in the regions take at least three different values. The values of n and Q decrease in a longer-term region. The decrease in Q value is the cause of the overestimation of long-term rupture life predicted by the conventional TTP methods unable to deal with the change in Q value. Therefore, before applying a TTP analysis to stress-rupture data, the data should be divided into several data sets so that Q value is unique in each divided data set. When this multi-region analysis is adopted, all the data points of the steels can be described with higher accuracy, and their long-term rupture life can be evaluated more correctly.

著者

Huseyin Aydin Elhachmi Essadiqi In-Ho Jung Stephen Yue

出版者

一般社団法人 日本鉄鋼協会

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.53, no.10, pp.1871-1880, 2013-10-15 (Released:2013-10-30)

参考文献数

22

被引用文献数

1 5

---

In the present work, the effects of intercritical annealing parameters on the microstructure and cold rollability (deformation rate and ratio) of “3rd Generation Advanced High Strength Steels (AHSS)” were studied. Hence, this paper discusses the formation of microstructures with different volume fractions of ferrite, martensite, bainite and retained austenite (RA). Two novel microstructures have been created, based on two levels of manganese (Mn): (i) ferrite plus martensite nucleated in austenite microstructure (FMNA structures), using Mn levels of 5 to 7 wt% and (ii) ferrite plus retained austenite duplex structure (FADP steels) for a Mn level of 10 wt%. In general, the ductility is a function of the amount of retained austenite and the strength is highly dependent on the martensite level.

著者

紙川 尚也 阿部 吉剛 宮本 吾郎 船川 義正 古原 忠

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.99, no.5, pp.352-361, 2013 (Released:2013-04-30)

参考文献数

46

被引用文献数

3 6

---

Tensile behavior and structure-property relationship of ferritic steels with nano-sized carbide dispersion were invesigated using Ti-added steel and Ti,Mo-added low carbon steels. By austenitizing followed by isothermal heat treatment at 700°C, polygonal ferrites containing very fine carbides of TiC and (Ti,Mo) C were obtained in the Ti-added and the Ti,Mo-added steels, respectively. The size of such carbides was finer in the Ti,Mo-added steel than in the Ti-added steel at the same holding period of isothermal heat treatment. The results of tensile tests for these samples showed that the strength is higher as the diameter of the carbides is smaller. The structure-based strength calculation led to a good agreement with the experiments, when it was assumed that the Ashby-Orowan mechanism is dominant for precipitation strengthening of nano-sized alloy carbides. It was also suggested that a relatively large tensile ductility is related to enhanced recovery during the tensile deformation, accompanied with promotion of secondary slips or cross slips in a finer scale due to the nano-sized particles.

著者

Yoshimasa Funakawa Tsuyoshi Shiozaki Kunikazu Tomita Tetsuo Yamamoto Eiji Maeda

出版者

一般社団法人 日本鉄鋼協会

雑誌

ISIJ International (ISSN:09151559)

巻号頁・発行日

vol.44, no.11, pp.1945-1951, 2004-11-15 (Released:2007-05-31)

参考文献数

24

被引用文献数

132 446

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A ferritic steel precipitation-strengthened by nanometer-sized carbides was developed to obtain a high strength hot-rolled sheet steel having tensile strength of 780 MPa grade with excellent stretch flange formability. Manganese in a content of 1.5% and molybdenum in a content of 0.2% were added to 0.04% carbon Ti-bearing steel in order to lower austenite-ferrite transformation temperature for fine carbides and to retard generating of pearlite and large cementites, respectively. Tensile strength of hot-rolled sheet steel increased with titanium content and it was achieved to 800 MPa in a 0.09% Ti steel. Microstructure of the 0.09%Ti steel was ferrite without pearlite and large cementites. Fine carbides of 3 nm in diameter were observed in rows in the ferrite matrix of the 0.09% Ti steel with transmission electron microscope. The characteristic arrangement of the nanometer-sized carbides indicates that the carbides were formed at austenite-ferrite interfaces during transformation. By energy dispersive X-ray spectroscopy, the carbides were found to contain molybdenum in the same atomic concentration as titanium. Crystal structure of the nanometer-sized carbides was determined to be NaCl-type by X-ray diffractometry. The calculated amount of precipitation-strengthening by the carbides was approximately 300 MPa. This is two or three times higher than that of conventional Ti-bearing high strength hot-rolled sheet steels.Based on the results obtained in the laboratory investigation, mill trial was carried out. The developed hot-rolled high strength sheet steel exhibited excellent stretch flange formability.