| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot dip galvanized high strength steel sheet and an alloyed hot dip galvanized high strength steel sheet each having a uniform, fine structure and excellent corrosion resistance and hole expandability, and to provide methods for producing them. SOLUTION: The hot dip galvanized high strength steel sheet is characterized by applying hot dip galvanizing to a steel sheet having a steel composition containing, by mass, 0.01 to 0.20% C,≤2.0% Si, 0.010 to 2.0% Al, 0.5 to 3.0% Mn,≤0.08% P,≤0.010% S and≤0.010% N, and having a ferrite-bainite structure consisting mainly of ferrite, and in which Mn microsegregation in the range of 1/8t to 3/8t of the sheet thickness t lies in the range satisfying inequality (1): 0.10≥σ≥/Mn; wherein, Mn denotes its additional amount; andσdenotes the standard deviation in Mn microsegregation measurement. COPYRIGHT: (C)2007,JPO&INPIT
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