Patent ID: 10106873

Abstract:
A hot-rolled steel sheet including, in terms of % by mass, 0.030% to 0.120% of C, 1.20% or less of Si, 1.00% to 3.00% of Mn, 0.01% to 0.70% of Al, 0.05% to 0.20% of Ti, 0.01% to 0.10% of Nb, 0.020% or less of P, 0.010% or less of S, and 0.005% or less of N, and a balance consisting of Fe and impurities, in which 0.106≥(C %-Ti %*12/48-Nb %*12/93)≥0.012 is satisfied; a pole density of {112}(110) at a position of ¼ plate thickness is 5.7 or less; an aspect ratio (long axis/short axis) of prior austenite grains is 5.3 or less; a density of (Ti, Nb)C precipitates having a size of 20 nm or less is 109 pieces/mm3 or more; a yield ratio YR, which is the ratio of a tensile strength to a yield stress, is 0.80 or more; and a tensile strength is 590 MPa or more.