| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high strength hot-dip galvanized steel sheet combining strength and workability (stretch flange formability) and a method for manufacturing the steel sheet. <P>SOLUTION: A hot-rolled steel sheet has a composition including, by mass%, 0.06% or more but 0.15% or less C, more than 0.3% but 0.5% or less Si, 0.5% or more but 2.0% or less Mn, 0.06% or less P, 0.005% or less S, 0.06% or less Al, 0.006% or less N, 0.08% or more but 0.2% or less Ti, 0.2% or more but 0.4% or less V, 0.04% or more but 0.2% or less Cr, and the reminder being Fe and unavoidable impurities. The hot-rolled steel sheet has a structure in which a matrix has, by an area ratio, a ferrite phase accounting for 98% or more with respect to the entire structure, the matrix has an equivalent dislocation density of 7.0×10<SP POS="POST">14</SP>m<SP POS="POST">-2</SP>or more but 1.0×10<SP POS="POST">15</SP>m<SP POS="POST">-2</SP>or less, and a deposit of a plate-like shape with a side of 10 nm or shorter and thickness of 1 nm or less is deposited in the matrix. A surface of the hot-rolled steel sheet is subjected to a hot-dip galvanized treatment or further to an alloying treatment. <P>COPYRIGHT: (C)2013,JPO&INPIT |
