| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a hot-dip galvanized steel sheet and an alloying hot-dip galvanized steel sheet that have a high strength of 1,180 MPa or more in tensile strength and superior delayed fracture resistance. <P>SOLUTION: High strength is ensured by a large addition amount of B. Specifically, a steel sheet includes, by mass, 0.11-0.20% C, 0.001-0.35% Si, 2.0-3.0% Mn,≤0.1% P,≤0.01% S, 0.001-1.5% sol. Al, 0.001-0.30% Ti,≤0.02% N, and≤0.0021-0.0080% B. In some cases, it may further contain one or more of Nb, V, Cr, Mo, Cu, Ni, Ca, REM, and Bi at appropriate amounts, and the sheet has a chemical composition satisfying formula (1): 15×sol. Al+100×Ti≥1.5 and the metal structure contains 7 vol.% or less of retained austenite. <P>COPYRIGHT: (C)2013,JPO&INPIT</p> |
