Tetsu-to-Hagane

[title in Japanese]

[in Japanese]

1968 Volume 54 Issue 6 Pages 641-642
Published: May 01, 1968
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.54.6_641

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The Effect of Ingot Size and Capping Time on the Distribution, Composition and Type of Non-Metallic Inclusion in Large Rimming Ingots

Koichi ASANO, Tetsuro OHASHI, Yoshio NURI

1968 Volume 54 Issue 6 Pages 643-672
Published: May 01, 1968
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.54.6_643

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The following results have been obtained through the study made on the subject.
(1) Large non-metallic inclusions distribute mainly at the bottom part of an ingot. Whose compositions are (Fe, Mn) O, MnO-Al₂0₃ and Mn-Silicate. From the fact that larger inclusions have less value of MnO/FeO, coming closer to the composition of scum, it is estimated that large inclusionsstem partially from scum through rimming action. Since Ca is detected in the aluminate and silicate, they are considered to have origin in slag, refractory and deoxidation products.
(2) With the “ingot parameter” Y-which is defined as ingot width/ingot thickness+0.02 (ingot height-width), relations between ingot dimensions and inclusion distribution and its composition can be clearly shown: when Y becomes bigger, total amount of inclusions and amount of large inclusions (more than 100μ) increase and the inclusions have less value of MnO/Fe0.
The parameter Y is considered to have some relationship with thickness of viscous laver at the bottom part of ingot and with state of flow of rimming steel in the mold. Y therefore, is a good index to explain conditions of scum movement along rimming action, scum trap and precipitation of (Fe, Mn) O.
(3) With shorter capping time, increase in total amount of inclusion is observed, but the amount of large inclusions decreases.
This result is explained as follows:
When capping time becomes shorter, more oxygen, which would be otherwise eliminated through rimming action as CO, remains to react with iron and manganese which results in higher amount of nclusion.
Growth of inclusions is hindered as rimming action is terminated earlier, which results in less amount of large inclusions.

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Identification of σ-Phase in 25Cr-20Ni Heat-Resistant Cast Steel

Tohei OTOTANI, Yasuzi KATAURA, Takashi SATO

1968 Volume 54 Issue 6 Pages 673-678
Published: May 01, 1968
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.54.6_673

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Some experiments were carried out by means of X-ray diffraction, electrolytic isolation and potentiostatic etching technique, in order to make clear the relation between precipitated carbides and σ-phase in 25Cr-20Ni heat-resistant cast steel.
The results obtained were summarized as follows:
(1) When electrolytic residues contain more than 5wt% of σ-phase, it can be identified by X-ray diffraction method.
(2) For the electrolytic isolation of σ-phase, 45wt% FeCl₃ aq. solution showed a favourable result as compared with 10vol% HCl-C₂H₅OH solution.
(3) Not only M₇C₃ is distinguishable from M₂₃C₆ carbide but also σ-phase from M₂₃C₆ by means of potentiostatic etching in 10 n-NaOH solution. At 200mV vs. Hg-HgO reference electrode M₂₃C₆ carbide is etched more rapidly than M₇C₃ carbide or σ-phase, at 500mV M₂₃C₆ and M₇C₃ carbides, or M₂₃C₆ and σ-phase are simultaneously etched, and at 600mV, σ-phase etched most rapidly.
(4) From these investigations it was found that σ-phase may be possible to precipitate even in the prolonged heat treated cast steel containing 0.35% carbon.

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On the Temperature Rise during Hot Rolling

Isao KOZASU, Hiroyuki KUBOTA

1968 Volume 54 Issue 6 Pages 679-680
Published: May 01, 1968
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.54.6_679

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The temperture rise due to hot rolling was qualitatively evaluated by rolling plates with inserted thermocouples. In rolling at high reductions, thermocouples were shortcircuited by oxidation scale in the vicinity of the junction. However, this was found to exert no influence on temperature readings.
The temperature rise ranged between 10°C and 45°C for the conditions studied (1150-800°C, 10-40% reduction), and showed a better correlation with mean flow stress rather than with amount of plastic work in rolling.

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On the Development of Cold-Rolling Textures in α-Iron

Taichi KAMIJO

1968 Volume 54 Issue 6 Pages 681-690
Published: May 01, 1968
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.54.6_681

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On the Quench-Aging of Steel

Genjiro MIMA

1968 Volume 54 Issue 6 Pages 691-709
Published: May 01, 1968
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.54.6_691

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Strength of Quenched and Tempered Structures of Steel

The Relation of Microstructural Strengthening Factors to Strength

Tatsuro KUNITAKE

1968 Volume 54 Issue 6 Pages 710-722
Published: May 01, 1968
Released on J-STAGE: October 12, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.54.6_710

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[title in Japanese]

1968 Volume 54 Issue 6 Pages 723-727
Published: May 01, 1968
Released on J-STAGE: December 22, 2010

DOIhttps://doi.org/10.2355/tetsutohagane1955.54.6_723

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