PRODUCTION OF HOT ROLLED STEEL PLATE REDUCED IN INPLANE ANISOTROPY AND HAVING HIGH R-VALUE

摘要

PURPOSE: To stably produce a hot rolled steel plate excellent in workability, reduced in inplane anisotropy, and having high r-value on an industrial scale. ;CONSTITUTION: A hot steel slab which has a composition containing ≤0.0-8% C, ≤0.3% Si, 0.01-0.5% Mn, ≤0.02% S, 0.01-0.08% solAl, and ≤0.01% N or further containing one or more kinds among prescribed amounts of B, Ti, Nb, Zr, V, and Mo in the percentages satisfying an inequality [C equivalent]-[Ti equivalent/4]≤0.0020 is successively treated by means of a process including at least the following treatments: (a) cooling down to a temp. in the region lower than the A₃ point; (b) precipitation treatment consisting of holding at a temp. lower than the A₃ point for 1-60min; (c) temp. rise up to a temp. ion the region between the A₃ point and [A₃ point+200°C] to cause inverse transformation from alpha to gamma; (d) cooling from the γ-phase temp. region; (e) rolling at a temp. between [A₃ point-100°C] and 450°C at 70-97% total draft; and (f) recrystallization treatment.;COPYRIGHT: (C)1994,JPO&Japio