| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high-strength thin steel sheet which, in spite of a reduced amount of Cu added, has hydrogen embrittlement resistance high enough for a cold-rolled steel sheet. <P>SOLUTION: The high-strength thin steel sheet is a high-strength thin steel sheet having a tensile strength of not less than 570 MPa, has the following chemical composition as a whole: 0.10-0.30 mass% C, 1.0-2.5 mass% Si, 1.0-3.5 mass% Mn, 0.016-0.09 mass% Cu, 1/2 or more of the Cu concentration to 0.20 mass% Ni or less, and the balance comprising iron and unavoidable impurities, and has a Cu concentration of not less than 0.10 mass% in the region lying from the surface to a depth of 0.4 μm. <P>COPYRIGHT: (C)2012,JPO&INPIT |
