Fatigue crack propagation velocity of the plate thickness direction is low thick steel plate and a method of manufacturing the same

摘要

PURPOSE: To produce a thick steel plate having prolonged fatigue life by controlling the texture of a steel plate and the recovery or recrystallization of ferrite and decreasing the crack propagation velocity in a plate thickness direction in the initial stage of fatigue crack propagation. ;CONSTITUTION: This steel plate has a composition consisting of, by weight, 0.015-0.20% C, 0.05-2.0% Si, 0.1-2.0% Mn, ≤0.05% P, ≤0.02% S, and the balance Fe with inevitable impurities and containing, if necessary, proper amounts of Cu, Ni, Cr, Mo, Nb, V, Ti, N, REM, and Ca. Further, the (200) diffraction intensity ratio in a plate thickness direction, measured by means of X-ray, is regulated to 2.0-15.0 and also the area ratio of recovered or recrystallized ferrite grains is regulated to 15-40%.;COPYRIGHT: (C)1996,JPO