Tetsu-to-Hagane

[title in Japanese]

[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...

1972 Volume 58 Issue 13 Pages 1751-1752
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1751

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An Outlined View on the Studies of Metallurgical Technology of Non-heattreated High Tensile Steels

Toru ARAKI

1972 Volume 58 Issue 13 Pages 1753-1758
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1753

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Fine-Grained Low Carbon Structural Steels with Small Additions of Niobium and/or Vanadium

Haruo KAJI, Shushi KINOSHITA, Noboru HAYASHI

1972 Volume 58 Issue 13 Pages 1759-1774
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1759

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Metallurgical Variables Involved in Controlled Rolling of High Tensile Steels and Its Application to Hot Strip

Tomoo TANAKA, Tei-ichi ENAMI

1972 Volume 58 Issue 13 Pages 1775-1790
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1775

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From the standpoint of improving the mechanical prop erties and particularly weldability in high tensile strength steels, much attention has been paid to the controlled rolling which has possibilities to make full use of potentiality existed in materials. In this paper, general review on this method is done. That is; firstly, the relation between mechanical properti es and microstructures is mentioned. Secondly, the important variables which affect controlled rolling are considered;(1) the amount of hot-working, (2) the temperature range over which hot-working is applied, (3) the rate of recrys-t allization in deformed austenite, (4) possible causes of the retardation of recrystallization by the addition of alloying elements, (5) the role of carbonitrides, (6) chemical composition of steels, and (7) the rate of cooling following rolling and particularly during the transformation range. Lastly, the application of the controlled rolling to hot strip is considered and typical examples of controlled rolled hot strips are exhibited.

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Characteristics of A1N-Bearing High Strength Steels

Kazuo TACHIMOTO, Yosinori SAIKA, Munemitsu FUKAGAWA

1972 Volume 58 Issue 13 Pages 1791-1805
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1791

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The Use of High Strength Steel for Civil Engineering Structures

Kohsuke HORIKAWA

1972 Volume 58 Issue 13 Pages 1806-1811
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1806

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Weld Crackability Formula of High Strength Steels

Yoshinori ITO, Kiyoshi BESSYO

1972 Volume 58 Issue 13 Pages 1812-1821
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1812

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On Fracture Toughness and Metallurgical Factors in High Tensile Steel

Hiroshi MIMURA

1972 Volume 58 Issue 13 Pages 1822-1831
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1822

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An Investigation on Controlled Rolling of Low Carbon Killed Steel

Minoru FUKUDA, Tamotsu HASHIMOTO, Kazutoshi KUNISHIGE

1972 Volume 58 Issue 13 Pages 1832-1847
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1832

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Three factors, namely, grain size, pearlite, and precipitation hardening have been chosen out of many factors contributing to the mechanical properties of hot rolled steel plates to study how hot rolling affects to the th ree factors and how hot rolling influences to the strength and touhness throughout them.
The results are as follows:
(i) The austenite/ferrite transformation behaviour changes by rolling temperature and Can be-classified. systematically. Especially, ferrite transformation is much promoted by large deibrmation in low temper ature.
(ii) The increase of pearlite volume fraction is clearly detrimental to the toughness in coarse grained steels but not so harmful in grain refined steels. And also the banding of pearlite by hot rolling seems to give a favourable effect on toughness.
(iii) The precipitation hardening with V or Nb raises charpy transition temperature, in the case of high finishing temperature, but not at low finishing temperature.
(iv) It is shown that the strength and toughness of hot rolled steel plates are affected by many factors and that the contribution of each factor varies considerably by rolling conditions.

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Investigation of Metallurgical Factors in the Production of High Strength Steel Plate with High Toughness by Controlled Rolling

Hiroyoshi MATSUBARA, Tatsumi OSUKA, Isao KOZASU, Koshiro TSUKADA

1972 Volume 58 Issue 13 Pages 1848-1860
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1848

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This paper describes a part of the results of a continuing developmental activity to obtain optimun chemical compositions and processing conditions in the production of high strength steel with excellent toughness by controlled rolling. It was noted in the laboratory experiment and mill test that Nb was most effective to improve fracture appearance transition temperature (_υT_s) when a strong controlled rolling was while V was less effective in this respect. Steels containing both Nb and V showed a _υT_s value sianilar to that of Nb bearing steels. Addition of small amounts of Ni, Cr, and Cu to Nb or V bearing steels enhanced precipitation hardening presumably by lowering γ-α: transformation temperature without deterioration of _υT_s-Lowering carbon content below a level of 0.07% in Nb bearing steel considerably improved impact shelf energy without any loss in LYS. Transverse shelf energy was also improved by a decrease in sulfur content and application of cross rolling. However, intensified controlled rolling slightly decreased shelf energy. The improvement of _υT_s by controlled rolling was consistently described by the total rolling reduction below 900°, and was less dependent on rolling reduction of individual pass. A combination of the above knowledges made it possible to produce tough high strength steels, and a few such examples of linepipe plate were shown.

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A Study of As-rolled Low-carbon, High Notch-Toughness Steels

Shizuya MAEKAWA, Katao MIYANO, Masahide SHIMAZAKI

1972 Volume 58 Issue 13 Pages 1861-1876
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1861

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Studies have been made in order to develop a new steel which is usable in as-rolled condition for low temperature service. Fine grained steels with low carbon contents of below 0.10% finish -rolled from relatively low reheating temperature, are expected to have ultrafine grains. The effects of chemical composition and rolling variables on the microstructures and notch toughness of low carbon fine grained steels are examined in relation to metallurgical factors.
The reasults are as follows:
(1) When the slabs are reheated at 900-950°C and finish-rolled with 50% total reduction, the ferrite grain size decreases progressively with the decrement of finish rolling temperature down to below 770°C until a limiting value.
(2) The addition of grain refiners such as vanadium, niobium, aluminium, titanium and manganese markedly refines the ferrite grain size of steels rolled from relatively low soaking temperature and yields a high notch toughness in as-rolled condition.
(3) As for the finish rolling variables, the soaking temperature of slab must be so selected that there are large amounts of precipitates remained insoluble and that they still act as grain refiners. The lower reheating tenperature yields a good notch toughness even after a small total deformation.
(4) The good notch toughness of steel plates rolled from low reheating temperature is mainly due to fine ferrite grain size, but partly due to mechanical fibering of ferrite and pearlite which may induce microfissuring in the plane of the plate at the notch root, with the effect that stress triaxiality is relieved and transition temperature depressed.
(5) A combioation of niobium and titanium as the grain refiners improves notch toughness, especially at the grain coarsed region of HAZ.
Based on the above results, a new weldable structural steel has been developed which contains small amount of nickel, but provides transition temperature as low as -100°C

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The Relation between the Alloying Elements and the Mechanical Properties of Low-carbon Low-alloy Bainite

Tatsuro KUNITAKE, Fukunaga TERASAKI, Yasuya OHMORI

1972 Volume 58 Issue 13 Pages 1877-1892
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1877

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The effect of alloying elements on the mechanical properties of bainite in some low carbon Ni-Cr-Mo ste-els was investigated, and was compared with that in tempered martensite. The bainite formation was achieved in a salt bath held at 350°C after the austenitization.
Although the heat treatment was carried out in the salt bath using the plates as thin as 7mm thick, the cooling rate was not fast enough to completely avoid the austenite decomposition prior to the isothermal trans-formation. Therefore, the variation of the mechanical properties of the bainite with the addition of alloying elements could mainly be interpreted in terms of the transformation characteristics. For instance, nickel improved both the strength and toughness of the bainite by lowering the formation temperature of the ba-inite, resulting in the fine bainite laths with cementite laths on a specific ferrite plane (B-III type bainite). This provided a fine unit crack path, which consisted of a bundle of the ferrite laths approximately sharing a common {100}α cleavage plane. It was shown that the results could be explained in terms of the unit crack path, the dislocation density, and the morphology of the precipitates.

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The Refinenient of Microstructures of Si-Mn High Strength Steel

Ryukichi OBARA, Ishige SHIGEMATSU

1972 Volume 58 Issue 13 Pages 1893-1902
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1893

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It is well known that rolling procedure considerably affects microstructures and mechanical properties of steels used in hot-rolled condition.
The properties of Si-Mn steels treated under various rolling and cooling conditions have been studied from the standpoint of the refinement of austenite and ferrite grain. The present results show that low heating and finishing temperatures and adequately controlled cooling rate are necessary to obtain finer ferrite-pearlite microstructures, and that these refinements are affected by the total reduction ratio rather than the amount of one pass reduction.

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Development of Structural High Strength Steels in Japan and Some Problems in Welding

Hiroshi KIHARA

1972 Volume 58 Issue 13 Pages 1903-1912
Published: November 01, 1972
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1903

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[title in Japanese]

1972 Volume 58 Issue 13 Pages 1913-1920
Published: November 01, 1972
Released on J-STAGE: December 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.58.13_1913

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