著者
大山 伸幸 岩見 友司 山本 哲也 町田 智 樋口 隆英 佐藤 秀明 佐藤 道貴 武田 幹治 渡辺 芳典 清水 正賢 西岡 浩樹
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.97, no.10, pp.510-518, 2011-10-01 (Released:2011-10-01)
参考文献数
42
被引用文献数
3 8

JFE Steel Corporation developed the hydrogen-based gas fuel injection technology for sintering machines to improve sinter quality without increasing coke breeze ratio. With the technology, it is possible to extend the temperature zone between 1200°C and 1400°C by injecting the gaseous fuel from the top surface of the sintering machine as a partial substitute for coke breeze. Theoretical and experimental studies were carried out to verify the effect of the gaseous-fuel injection technology on pore structure in the sinter cake with the X-ray CT scanner and sintering pot test.It is important to hold the temperature between 1200°C and 1400°C in order to produce high strength and high reducibility sinter. The liquid phase ratio can be increased with extending the proper temperature zone by applying the gaseous fuel injection technology. The increase in liquid phase ratio promotes the combination of pores (1–5 mm) and sinter strength is improved. At the same time, the pores over 5 mm growth are promoted and the permeability is improved in the sintering bed. Moreover, the low-temperature sintering process depresses the iron ore self-densification. Micro pores under 1 μm remain in unmelted ores and improve sinter reducibility. As a result, the technology enables to improve the pore structure in the sinter cake and sinter quality.The technology was put into commercial operation at Keihin No. 1 sinter plant in January 2009 and stable operation has continued up to the present. As a result, the energy efficiency in the sintering process is greatly improved, and it has been achieved to reduce CO2 emissions by a maximum of approximately 60000 t/year at Keihin No. 1 sinter plant.
著者
村尾 明紀 柏原 佑介 大山 伸幸 佐藤 道貴 渡壁 史朗 山本 耕司 福本 泰洋
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.102, no.11, pp.614-622, 2016 (Released:2016-10-31)
参考文献数
30
被引用文献数
3 4

Increased gas utilization and improved permeability have been desired in order to achieve low RAR (Reducing Agent Rate) operation of blast furnace. Coke mixed charging in the ore layer is one effective measure for realizing these improvements. A burden distribution control technique for mixing small coke at a blast furnace with a parallel type and center feed type bell-less top were developed and investigated in an experiment with a scale model of an actual blast furnace at JFE Steel. The scale model consists of an ore bin, a coke bin, a surge hopper, belt conveyers, a bell-less top and a model furnace to simulate the charging system of the actual blast furnace. The mixed coke ratio at the furnace top was controlled by the discharge pattern of mixed small coke and ore, and mixing position. The optimum patterns were founded to discharge the small coke from the coke bin after the ore discharged from ore bin in center feed bell-less top, and to discharge the small coke on the ore at front of quarter part overlapped in parallel type bell-less top. These patterns were applied to the actual blast furnace, and the improvement of permeability in a furnace was confirmed by the effect of increase the mixed small coke yield into ore layer.
著者
篠竹 昭彦 内藤 誠章 尾松 保彦 赤木 一志 坪田 淳 村瀬 伸 菊池 善悦 鈴木 啓之
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.3, pp.185-190, 2013 (Released:2013-02-28)
参考文献数
7
被引用文献数
1 2

In the scrap-melting operation of shaft furnaces, an operation technology with use of 100% small size blast furnace coke for solid fuel instead of typically utilizing foundry coke has been established. An operation technology with use of 100% steel scrap without using return scrap containing 3-4 % carbon for ferrous raw material, and 70% or more of steel scrap consists of shredder scrap, has been established as well.This technology was first developed with one-stage tuyere operations using only lower tuyeres. Next two-stage tuyere operations using lower and upper tuyeres has been developed to explore more efficient operation.In the two-stage tuyere operation, the number of pipes, the diameter, and the protruding length of the upper tuyeres were examined as parameters, an operation technology with high efficiency was established, which enabled us to achieve high productivity and low coke ratio.
著者
篠原 虔章 高橋 明人 白石 典久
出版者
社団法人日本鉄鋼協会
雑誌
鐵と鋼 : 日本鐡鋼協會々誌 (ISSN:00211575)
巻号頁・発行日
vol.64, no.13, pp.1959-1967, 1978-11-01

Hot slabs after the slabbing mill are at a mean temperature of 1000℃ and have the sensible heat of 160×10^3 kcal/t-slab. The main features of a Slab Cooling Boiler (SCB) are the recovery of the sensible heat to steam (16kg/cm^2G) by mean of heat radiation from the surface of hot slabs, and continuation of cooling process of almost every kind of slab. The first installation of an SCB was completed at Slabbing Mill No.2 in Mizushima Works of Kawasaki Steel Corporation and it has been operating successfully since March, 1976. The capacity of the heat recovery in this SCB is 72000kcal/t-slab. It is equal to or greater than the heat consumption of rimmed and semikilled steel in the soaking pit. This paper discusses the basic heat transfer experiments performed under this development, the basic planning of the installation, the outlines of the system, and some results of the operations.
著者
松本 和久 秦野 正治 大宮 慎一 藤井 秀樹
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.103, no.1, pp.54-63, 2017 (Released:2016-12-31)
参考文献数
40
被引用文献数
4 5

To investigate an effect of internal hydrogen on mechanical properties of a new austenitic stainless steel “STH2” having a nominal composition of Fe-15%Cr-9%Mn-6%Ni-2.5%Cu-0.15~0.2%N, tensile tests and fatigue crack growth tests were conducted for the specimens containing around 80 ppm hydrogen charged by the exposure in 45 MPa hydrogen gas at 300˚C for 200 h and the ones heat treated in air with the same heat pattern.At room temperature and –40˚C, no significant ductility drop by hydrogen charging was observed and about 80% of relative reduction of area was obtained, which is the same as that of JIS SUS316L with the same amount of internal hydrogen. In the specimens tensile tested at –40˚C, a small quantity of quasicleavage fracture surfaces were observed. In the banded areas in which Mn, Ni and Cu were negatively segregated, some relatively coarse voids coalesced with cracks extended along the maximum shear stress plane, which is similar to what is called void-sheet type of fracture. It is quite different from the case for tensile tests in 90 MPa hydrogen gas, in which coarse longitudinal cracks form, suggesting that the concentration of hydrogen at crack tips in 90 MPa hydrogen gas is higher than 80 ppm. It was also confirmed that fatigue crack growth rates were not accelerated by 80 ppm internal hydrogen although some faceted fracture surfaces composed of (111) γ formed.It is confirmed that STH2 has excellent properties not only in high pressure hydrogen gas but also in the circumstance of internal hydrogen of around 80 ppm.
著者
安藤 玲音 松野 崇 松田 知子 山下 典理男 横田 秀夫 後藤 健太 渡邊 育夢
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.106, no.12, pp.944-952, 2020 (Released:2020-11-30)
参考文献数
21

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
福島 英二
出版者
The Iron and Steel Institute of Japan
雑誌
鉄と鋼 (ISSN:00211575)
巻号頁・発行日
vol.61, no.10, pp.2501-2513, 1975-08-01 (Released:2010-10-12)
参考文献数
54
被引用文献数
1 1
著者
棗田 浩和 北原 周 橋本 俊一
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.102, no.9, pp.525-533, 2016 (Released:2016-08-31)
参考文献数
31
被引用文献数
9 14

Recently, 5% Mn steel has been focused on as one of the promising candidates for third generation AHSS by showing an excellent TS-El 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 reverted 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. On the other hand, the steel which did not contain retained austenite in a mother hot band exhibited excellent strength-elongation 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.
著者
足立 吉隆 新川田 圭介 奥野 晃弘 弘川 奨悟 田口 茂樹 定松 直
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.102, no.1, pp.47-55, 2016 (Released:2015-12-31)
参考文献数
19
被引用文献数
6 6

Prediction of a stress-strain curve of ferrite-martensite DP steels was studied by a combined technique of Bayesian inference and artificial neural network. To screen a descriptor to be used for neural network analysis, material genomes such as volume fraction, micro-hardness, handle, and void of martensite phase, and micro-hardness of ferrite phase were examined by Bayesian inference. In a case of small data set, a machine learning method to predict mechanical properties reliably was proposed.
著者
弘川 奨悟 田口 茂樹 松下 康弘 足立 吉隆
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.103, no.8, pp.468-474, 2017 (Released:2017-07-31)
参考文献数
12
被引用文献数
1 1

Screening important microstructure factors dominantly controlling a stress-strain curve of a dual phase steel was studied by three kinds of sparse modelling approach; Sensitive analysis, data transformation & variable selection, and Bayesian inference. In addition, an effect of data noise on descriptor screening in sparse modelling was also investigated.
著者
嘉村 平八
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.17, no.2, pp.109-118, 1931
被引用文献数
2

Some years ago, the author has published on the foundamental investigation of the reduction of iron ores by hydrogen, on the Meiji Senmon Gakko Gahuho and the Journal of Iron and Steel Institute. In this investigation he made the experiment of reduction by hydrogen on the different kinds of ore, from 2, 000 to 5, 000 grams to investigate the properties of melted iron produced from the reduced iron. He determined proper temperature and time of the reduction in nearly industrial scale using the iron sands from Sanin and Kuji, and the iron ores from Taihei, Johole, Tochu, Ansan and the mill scales. The sponge iron after reduction was made as brickets under the pressure, 2 tons per square inch. From 1kg, to 1&middot;5kg. of the brickets is melted in an electric resistance furnace made by carbon-tube and cast as ingot. The phenomena of the melting was observed, and the degree of the reduction of phospkorus and sulphur was estimated, also, the impurities in the iron was analysed.<BR>The ingot iron obtained by the melting was forged after heating and compared the physical properties of the iron produced by different kind of ores<BR>Generally, it is known, in the blast furnace working, that nearly all the phosphorous in the charge is reduced and goes into the pig iron and it is impossible to remove the phosphorous into the slag. But, in this e all the phosphorous is not reduced on account of low temperature of reduction and the ureduced phosphorous which exist as its oxide is removed in the slag during the melting. It is recognized that the degree of reduction changes by the temperature of reduction. To confirm this phenomena, the high phosphorous iron ores, Taihei and Johole is reduced in different temperatures between 600&deg;C and 1, 100&deg;C and investigated the phosphorous content in the iron and slag obtained by the melting of the sponge iron to observe the influence of the temperature on the reduction of phosphorous.
著者
嘉村 平八
出版者
社団法人日本鉄鋼協会
雑誌
鐵と鋼 (ISSN:00211575)
巻号頁・発行日
vol.18, no.4, pp.405-410, 1932

The phosphorus in the iron and steel gives most injurious effect on their properties as well as sulphur, so that it is encouraged to eliminate the phos-phorus as lower as possible in their manufacture.<BR>There are many literatures as to the effects of phosphorus on the mechanical properties of steel, but as its effects change by the amount of carbon and other impurities in it, it is impossible to specify the limit of phosphorus content which is not objectionable to the properties of steel, and also it is impossible to express the change of mechanical properties by the increase of phosphorus content.<BR>The author made the phosphor-irons which contain the phosphorus from 0.014 to 0.91 per cent with very small amount of carbon and other impurities, and he investigated the effect of phosphorus on the mechanical and physical properties of iron.