| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-strength galvannealed steel sheet capable of stably obtaining higher fatigue durability than heretofore. SOLUTION: In the high-strength galvannealed steel sheet having galvannealed layer on the high-strength steel sheet, the high-strength steel sheet has≥5% the volume ratio of the retained austenite and≥10% the total of volume ratios of bainite and martensite, and in the interface between the galvannealed layer and the high-strength steel sheet, the thickness of a range, in which Fe concentration with GDS (glow discharge spectrometry) becomes 20-90%, is≥1.2μm. Thereby, the high strength, high workability and high fatigue-durability can simultaneously be obtained. COPYRIGHT: (C)2008,JPO&INPIT
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