Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
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Volume 97, Issue 7
Displaying 1-7 of 7 articles from this issue
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Fundamentals of High Temperature Processes
Regular Article
  • Wetting Behaviors of Steels Containing Al and Al–S on Solid CaO
    Takeshi Yoshikawa, Kazuya Motosugi, Toshihiro Tanaka, Mitsuru Ueda
    Article type: Regular Article
    Subject area: Fundamentals of High Temperature Processes
    2011 Volume 97 Issue 7 Pages 361-368
    Published: July 01, 2011
    Released on J-STAGE: July 01, 2011
    DOIhttps://doi.org/10.2355/tetsutohagane.97.361
    JOURNAL OPEN ACCESS
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    Wettability between refining agent and molten steel is an important factor in the refining process due to its great influence on the reaction interface. In the present study, wetting behaviors of steels containing Al and Al–S on CaO substrates were investigated by the sessile drop method at 1550°C in order to understand the interfacial phenomena during the refining of steel with solid CaO. Contact angle of steel containing Al on a CaO substrate was smaller than that of pure iron. The contact angle decreased with the smaller addition of Al, which could be explained from the amount of slag formation by the reaction between steel and CaO. The contact angle of steel containing Al–S was larger with the higher initial Al content and increased during the holding. It was mostly affected by the surfactant effect by soluble sulfur, and the wettability deteriorated by the progress of desulfurization.
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Casting and Solidification
Regular Article
  • In-Situ Observation of Behavior of Equiaxed Grains in Horizontal Centrifugal Casting Process
    Hisao Esaka, Jun-ichi Hiramoto, Shota Miyahara, Kei Tokusashi, Kei Shi ...
    Article type: Regular Article
    Subject area: Casting and Solidification
    2011 Volume 97 Issue 7 Pages 369-375
    Published: July 01, 2011
    Released on J-STAGE: July 01, 2011
    DOIhttps://doi.org/10.2355/tetsutohagane.97.369
    JOURNAL OPEN ACCESS
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    Centrifugal casting technique has been widely used to produce long products, such as pipes. In this casting, sometimes problems such as macroscopic segregation arise. However, we have not found effective countermeasures. This reason may be attributed to the fact that solidification under being applied centrifugal force itself has not been well understood. Therefore, in order to understand the solidification process in centrifugal casting, in-situ observations using transparent substance have been performed by an experimental equipment newly developed. One of the advantageous points of this equipment is that a video camera is installed on the rotating shaft enabling observation of predetermined area during whole period of solidification. Owing to the thermal gradient imposed, transparent substance solidifies inward.
    At the initial stage, columnar dendrites grew from the rim. Then, equiaxed grains formed in the liquid phase. Equiaxed grains oscillated not only in radial direction but tangential direction synchronized with the rotation. This movement became smaller as solidification proceeded. This change in oscillation with time is due to the increase of apparent viscosity as solidification proceeds.
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Forming Processing and Thermomechanical Treatment
Regular Article
  • Effect of Grain Size on Transcription Property of Die Shape in Micro Forming of SUS304
    Masahito Katoh
    Article type: Regular Article
    Subject area: Forming Processing and Thermomechanical Treatment
    2011 Volume 97 Issue 7 Pages 376-381
    Published: July 01, 2011
    Released on J-STAGE: July 01, 2011
    DOIhttps://doi.org/10.2355/tetsutohagane.97.376
    JOURNAL OPEN ACCESS
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    The microforming of SUS304 stainless steel with fine grain structures is carried out utilizing superplastic phenomenon. The configurations of formed structures are studied, and transcription properties are discussed. In this study, two types of experiments were carried out. One involved tests to form a micro-pyramid on the specimen by Vickers indentation as the die, and the other involved tests to form micro gratings by grinding mark as the die. The processed materials could not make contact to dies at the area around the top of the micro pyramid, which was 4–5 times the diameter of the grain size. It is believed that the flow into the top of the pyramid was blocked by the formation of a bridge of grains. And the lower limit to form micro gratings utilizing superplastic phenomenon was determined to be of the same size as of the grain of processed material.
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  • Analysis of Square Shell Deep Drawing Test of Ti–3Al–2.5V Sheet
    Tetsuro Ohwue, Arata Saito, Kazuhiro Takahashi, Hideki Fujii, Kohsaku ...
    Article type: Regular Article
    Subject area: Forming Processing and Thermomechanical Treatment
    2011 Volume 97 Issue 7 Pages 382-387
    Published: July 01, 2011
    Released on J-STAGE: July 01, 2011
    DOIhttps://doi.org/10.2355/tetsutohagane.97.382
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    FEM analysis utilizing Barlat–Lian'89 anisotropy model and square shell deep drawing test at room temperature were carried out in order to improve the formability of Ti–3Al–2.5V sheet. As for the flange wrinkle, FEM analysis coincide with the experimental result more in case of 1.5% R-value than that of 5% R-value. The bigger the ΔCL , the greater the flange wrinkle. On the contrary the bigger the Rave, the smaller the flange wrinkle. Moreover, flange wrinkle decreases abruptly when Rave becomes equal or exceeds 2.0 in case that forming height becomes maximum value of 30 mm. And the flange breakage, occurs at the straight region of C-direction, proved to be caused by the shear stress.
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  • Evaluation of Occurrence of Sticking and S Additive in Hot Rolling of Stainless Steel
    Takahiro Toriumi, Akira Azushima
    Article type: Regular Article
    Subject area: Forming Processing and Thermomechanical Treatment
    2011 Volume 97 Issue 7 Pages 388-392
    Published: July 01, 2011
    Released on J-STAGE: July 01, 2011
    DOIhttps://doi.org/10.2355/tetsutohagane.97.388
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    The sticking during hot strip rolling of ferritic stainless steel is evaluated using a tribo-simulator developed by the authors. The experiments of sliding rolling with an emulsion of Colza oil are carried out changing rolling conditions of rolling speed and rolling reduction using specimens of SUS430 and rolls with HSS (High Speed Steel). From these experimental results, it is confirmed that the sticking during strip rolling of ferritic stainless steel can be evaluated using the tribo-simulator. Then, the effects of S additive on the sticking are investigated. The experiments are carried out using emulsions of Colza oils with S additive contents of 20, 30, 50 and 80%. The limitation reduction when occurring the sticking increases with increasing S additive content.
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  • Oxide Scale Behavior and Rolling Characteristics in Hot Steel Rolling
    Kenichiro Hara, Hiroshi Utsunomiya, Tetsuo Sakai, Shusuke Yanagi
    Article type: Regular Article
    Subject area: Forming Processing and Thermomechanical Treatment
    2011 Volume 97 Issue 7 Pages 393-398
    Published: July 01, 2011
    Released on J-STAGE: July 01, 2011
    DOIhttps://doi.org/10.2355/tetsutohagane.97.393
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    In hot steel rolling process, oxide layer, i.e. scale, is formed on surface by oxidation. The scale may influence friction between rolls and workpiece and affect rolling characteristics. In this study, low carbon steel sheet was inserted to a furnace at 1173K, 1273K, 1373K filled with argon. After 900 s, the atmosphere was changed to air to allow oxide scale to grow for 0, 10, 40 s. After the oxidation, the sheet was immediately rolled by 10–30% on a two-high laboratory mill. After passing the roll bite, glass powder was sprinkled over the sheet to suppress secondary oxidation.
    If the oxidation time is 0 s, the thin scale deforms relatively uniformly at all the three temperatures. At 1173K, if the oxidation time is 40 s, the scale is indented to the matrix steel, the interface between the scale and the matrix steel roughens apparently. At 1273K, the scale fractures and the matrix steel is extruded through cracks to outermost surface. At 1373K, the scale cracks in thickness direction, however the interface between the scale and the steel is smooth. The rolling force is not sensitive to the oxidation time at 1173K. At 1273K and 1373K, However, when the reduction is high, the force decreases with oxidation time. In these cases, the internal shear deformation decreases with oxidation time. It is supposed that thick scale tends to fracture and decreases the shear deformation by introducing relative sliding between the rolls and the matrix steel.
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Transformations and Microstructures
Regular Article
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