PURPOSE: To obtain an extremely thick steel plate having sound and uniform quality without preliminary forging by specifying the hydrogen content and segregation element value of a unidirectionally solidified ingot and limiting a rolling method.
CONSTITUTION: The hydrogen content in a unidirectionally solidified ingot is regulated to ≤1.5ppm, the segregation element B value expressed by the equation I to ≤0.2 and the thickness to ≥400mm. In the equation I , (x); the length on the long side of a billet, (y); the length on the short side of the billet, (a); the max. width of the area where inverted V segregation is formed. Such unidirectionally solidified ingot is rolled in such a way that the sum Seff value of the effective rolling stress in the direction perpendicular to the central part of the thickness expressed by the equation II is regulated to ≥0.1 in the stage of <4 total rolling ratio. In the equation II, σtcmax; the max. compressive stress in the direction perpendicular to the central part of the plate thickness, K0; the pure deformation resistance.
KAMIMURA MUNETOMO
YANO KOUZOU
YAMADA MAKOTO
TAKIGAWA NOBUTAKA
NABA YASUYUKI
| JPS5653802A | 1981-05-13 | |||
| JPS5159747A | 1976-05-25 |
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