HOT-ROLLED STEEL SHEET AND METHOD FOR PRODUCING SAME

摘要

Provided is a hot-rolled steel sheet that has a chemical composition including, by mass%: C: 0.060 % to 0.150 %; Si 0.15 % to 0.70 %; Mn: 1.00 % to 1.90 %; P: 0.10 % or less; S: 0.010 % or less; Al: 0.01 % to 0.10 %; N: 0.010 % or less; Nb: 0.010 % to 0.100 %; and the balance being Fe and incidental impurities. The hot-rolled steel sheet has a microstructure containing ferrite of 18 µm or less in average grain size by a volume fraction of at least 75 % and pearlite of at least 2 µm in average grain size by a volume fraction of at least 5 %, the balance being low-temperature-induced phases, the pearlite having a mean free path of at least 5.0 µm. The hot-rolled steel sheet can be suitably utilized for producing a cold rolled steel sheet or hot-dip galvanized steel sheet having excellent material homogeneity and a tensile strength of 590 MPa or more.