Hot-dip galvanized steel sheet and alloyed hot-dip galvanized steel sheet, each having excellent workability, high yield ratio and high strength

摘要

Disclosed is a hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet, which has a tensile strength of 980 MPa or more, excellent workability, high yield ratio and high strength. The hot-dip galvanized steel sheet or the alloyed hot-dip galvanized steel sheet is characterized by containing 0.12-0.3% by mass of C, 0.1% by mass or less (excluding 0% by mass) of Si, 2.0-3.5% by mass of Mn, 0.05% by mass or less (excluding 0% by mass) of P, 0.05% by mass or less (excluding 0% by mass) of S, 0.005-0.1% by mass of Al and 0.015% by mass or less (excluding 0% by mass) of N, with the balance made up of iron and unavoidable impurities. The hot-dip galvanized steel sheet or the alloyed hot-dip galvanized steel sheet is also characterized in that the metallic structure thereof contains bainite as a matrix structure, and the area ratio of ferrite is 3-20% and the area ratio of martensite is 10-35% relative to the entire structure.

主权项

1. A galvanized steel sheet, comprising, in mass percent:
C: 0.12-0.3%; Si: greater than 0 and 0.1% or less; Mn: 2.0-3.5%; P: greater than 0 and 0.05% or less; S: greater than 0 and 0.05% or less; Al: 0.005-0.1%; N: greater than 0 and 0.015% or less; with the balance being iron and unavoidable impurities, and a hot-dip zinc plating layer or an alloyed hot-dip zinc plating layer on the surface of the galvanized steel sheet, wherein the galvanized steel sheet has a tensile strength of 980 MPa or more, excellent workability and high yield ratio, metallic structure thereof contains bainite as a matrix structure, an area ratio of ferrite: 3-18%; and an area ratio of martensite: 10-35% in terms of ratio to the entire structure.