| 摘要 |
PROBLEM TO BE SOLVED: To provide a P-containing high-strength steel sheet to be galvannealed which has bake hardenability and inhibits the occurrence of a surface defect such as a streak pattern, and to provide a galvannealed steel sheet. SOLUTION: The steel sheet to be galvannealed comprises, by mass%, 0.0001-0.015% C, 0.001-0.45% Si, 0.20% or more Mn, 0.02% or more P, 0.015% or less S, 0.008% or less Al, 0.002-0.10% Ti, 0.0005-0.004% N, further one or more elements of Ce, La, Nd, Pr and Sm in a total amount of 0.0001-0.01%, and the balance Fe with unavoidable impurities; and further comprises acid soluble Ti so as to satisfy a condition given in the following formula (1): [%C]×4+[%N]×48/14-0.006%≤[%Ti]≤[%C]×4+[%N]×48/14-0.002%. COPYRIGHT: (C)2007,JPO&INPIT
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