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Volume 74 (2003)
- Issue 4 Pages 221-
- Issue 3 Pages 147-
- Issue 2 Pages 75-
- Issue 1 Pages 5-
Volume 74, Issue 1
Steelmaking and Recycling
Displaying 1-9 of 9 articles from this issue
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Paper
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Koki Morita, Toshio Suzuki2003 Volume 74 Issue 1 Pages 5-12
Published: January 15, 2003
Released on J-STAGE: May 06, 2010
JOURNAL FREE ACCESSSolidification macro-segregation, particularly in the form of freckles, in nickel base superalloys is the main cause for the limitation of ingot diameter and melting rate during vacuum arc remelting (VAR) and electro-slag remelting (ESR) processes.
The critical solidification conditions for freckle formation in INCONEL718 were experimentally studied by horizontal directional solidification (H-DS) under various solidification conditions, and validated by commercial sized VAR operation. The tendency for freckle formation in this alloy was evaluated by an expression based on modified Rayleigh criterion (Ra*) including solidification rate, thermal gradient in the mushy zone, and solidification front angle to the horizontal plane. In order to systematize the methods to predict proper VAR operating conditions, simulation method to calculate the Ra* as an indication for occurrence of freckle in solidification has been developed based on the results of the above experiments. It is found that there is a good agreement between calculation and experiments for distribution of freckle defects in the alloy.View full abstractDownload PDF (517K) -
Makoto Hobo, Masafumi Sakata, Tomoki Shibata2003 Volume 74 Issue 1 Pages 13-20
Published: January 15, 2003
Released on J-STAGE: May 06, 2010
JOURNAL FREE ACCESSVanadium is expected to be used as an element in hydrogen storage alloys. One of the main obstacles to this metal being used more commonly in this way is its cost. Pure V refined by electron beam furnace costs more than 60,000 yen/kg in Japan.
This paper aims for the realization of a cost efficient process for producing pure V, by refining Al-95V alloy which is almost as cheap as a tenth of pure V. The cold crucible was chosen as a refining furnace because it does not use ceramic crucibles, which would react with the molten vanadium and impurify it.
The combination of two successive processes was invented. In the first process, Al2O3 was removed by slag-metal reaction. In the second process, Misch metal was used for deoxidization. Ti7Cr12.5V78.5Mn2 which was produced by this new method showed good performance as a hydrogen storage alloy.View full abstractDownload PDF (174K) -
Toshiyuki Kozuka2003 Volume 74 Issue 1 Pages 21-28
Published: January 15, 2003
Released on J-STAGE: May 06, 2010
JOURNAL FREE ACCESSA new process for mixing and separating operation between two liquid layers are proposed, where both a direct electric current and a stationary magnetic field are imposed. An electromagnetic force appearing upward or downward can be utilized for scattering phenomena in a mixing region, controlling of buoyancy in a keeping region, and absorbing behavior in a separating region.
In scattering phenomena, a liquid dome created by an upward force is broken to become many metal droplets. The electromagnetic force necessary to scatter is several times to a gravitational force.
In controlling buoyancy process, about 40% of imposed electromagnetic force is effective for controlling upward velocity or downward velocity of liquid droplets.
In separation phenomena, a liquid droplet on the interface can be absorbed to metal layer by a downward force where the energy due to electromagnetic force can overcome the surface energy.View full abstractDownload PDF (424K) -
Tatefumi Sugiyama, Kazunori Onaka, Hiroshi Matsui2003 Volume 74 Issue 1 Pages 29-34
Published: January 15, 2003
Released on J-STAGE: May 06, 2010
JOURNAL FREE ACCESSA direct reduction process using carbon composite pellets is now received much attention because of the ability to recycle various metallic wastes. Some features of direct reduction using carbon composite pellets for Zn reaching residue are shown by the labo-scale experiments in this paper. High removal performance for Zn from wastes and melting behavior below 1573K was identified.View full abstractDownload PDF (331K)
Review
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Shizunori Hayakawa, Toru Tateishi, Yoshinori Masaki, Toshiki Watanabe2003 Volume 74 Issue 1 Pages 35-42
Published: January 15, 2003
Released on J-STAGE: May 06, 2010
JOURNAL FREE ACCESSGlobal environment preservation is vital for mankind to enjoy a healthy and comfortable life. While environment problems such as global warming, together with ever diminishing resources and energy are even more serious, the most significant challenge for all humanity now is to protect our precious global environment. To achieve this, every individual must consider "what one can do for the sake of the earth" and together we must strive to construct a recycling-oriented society that minimizes emission and waste. In manufacturing industries, various efforts have been aiming for "Zero Emission" factory. Daido Steel has developed several recycle technologies to utilize wastes e.g. slag, dust, used refractories and others.
In this paper, we have established some know how concering several waste recycle technolgies.View full abstractDownload PDF (521K)
Technical Paper
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Yoshio Inagaki, Hajime Amano, Akihiro Nagatani, Kenji Mori, Atsushi Ha ...2003 Volume 74 Issue 1 Pages 43-47
Published: January 15, 2003
Released on J-STAGE: May 06, 2010
JOURNAL FREE ACCESSIn Japan, steelmaking of electric arc furnace melting have two problems. (1)Electricity cost in the day-time is much more expensive than that in the night-time. (2)It is difficult to use much old scraps because of their tramp elements increasing in the scrap.
Daido Steel has developed the new vessel called "SV" (SV: Storage Vessel). The SV can keep molten steel melted during the night-time. In the day-time, the molten steel stored in the SV is tapped and mixed with scraps in the electric arc furnace. This process is called "AN" (AN: Anticipate the Next) process in Daido Steel. AN process can reduce the electric power consumption considerably in the day-time.
On the other hand, molten steel melted during the night-time is mixed in the SV, and SV enables tramp elements to be uniform. AN process makes it possible to decrease deviation of the tramp element.
In this paper, the outline of AN process is described, and some operational results are also reported herein.View full abstractDownload PDF (1426K) -
Hajime Amano, Akihiro Nagatani, Jun Eguchi2003 Volume 74 Issue 1 Pages 49-54
Published: January 15, 2003
Released on J-STAGE: May 06, 2010
JOURNAL FREE ACCESSDaido Steel developed a new refining process of stainless steel, AOD-VCR (Vacuum Converter Refiner) process in Shibukawa Plant in 1989, which makes it possible to replace dilution process of AOD with vacuum process at the final stage of decarburization period and the reduction period.
At present Argon gas consumption as dilution gas occupies more than 30% of total stainless refining cost of AOD-VCR process in Chita Plant and it is important to save the consumption.
Therefore we analyzed the change of nitrogen content during AOD-VCR process and introduced nitrogen estimation formula.
The nitrogen estimation formula could optimize gas injection pattern of AOD-VCR operation and save the Ar gas consumption.View full abstractDownload PDF (1334K) -
Masanori Kojimori, Katuyuki Nemoto, Toshiro Fukuokaya, Shinjiro Uchida ...2003 Volume 74 Issue 1 Pages 55-59
Published: January 15, 2003
Released on J-STAGE: May 06, 2010
JOURNAL FREE ACCESSRecently, the improvement of working environment for treating electric arc furnace slag and the expansion of uses for treated slag as the product have become an important issue in Japan. To solve these problems, OJI Steel Co., Ltd. has introduced the new slag granulating equipment developed by Nippon Steel Corporation and Hamada Heavy Industries, Ltd. which has the following features.
(1) The combination of mechanical crushing in a two-stage rotating drum and quick cooling by water spraying enables to direct production of granulated slag as the product from molten slag with low energy consumption.
(2) The product is small spherical particles which promise wider applications due to their physical properties.
(3) Compared to the conventional slag treatment which involves slow cooling in a pit and mechanical crushing of solid slag, the working environment is improved and plant space is economized.
The manufacturing technology of slag particles with mixing the oxidation slag and the reduction slag has been established by Oji Steel though operation wise improvement for stable slag granulation after its start-up in May 2000.View full abstractDownload PDF (289K) -
Kazumi Yamanoto, Tomoki Shibata2003 Volume 74 Issue 1 Pages 61-66
Published: January 15, 2003
Released on J-STAGE: May 06, 2010
JOURNAL FREE ACCESSIt is widely recognized that a cold crucible furnace enables to supply low impurity and high temperature of molten metal. A water-cooling copper crucible is used in the furnace and slits are created in it. They allow the magnetic flux generated by the field current of the heating coil to enter into the crucible. A shape of slit seriously affects an efficiency of the furnace. In this study the magnetic-flux density in the crucible has been measured and the effect of the slit shape on the magnetic field in the crucible has been investigated. Widening the width of the slit and separating the segments of the crucible accelerate to enter the magnetic flux into the crucible and increase the magnetic-flux density in it. The consumption of the electric power at the crucible is reduced and the efficiency of the furnace is improved consequently.View full abstractDownload PDF (214K)
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