| 摘要 |
PROBLEM TO BE SOLVED: To provide a high strength galvannealed steel sheet having excellent adhesion of hot-dip galvanizing as an upper layer even if a steel sheet as a basis material contains large amounts of Si and Mn and also having excellent corrosion resistance of plated steel sheet, and also to provide its manufacturing method. SOLUTION: In the high strength galvannealed steel sheet, respective contents of Si, Mn and B in a galvannealing layer satisfy specific relations, on a steel sheet composed of low-carbon steel containing specific amounts of Si, Mn and B. After heating the steel sheet, a prescribed amount of oxide film is formed and then removed by pickling to the prescribed amount, followed by hot-dip galvanizing and alloying.
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