| 摘要 |
PROBLEM TO BE SOLVED: To produce a hot dip galvannealed steel sheet in which unplating is prevented in hot dip galvannealing to an Si-added steel sheet and to provide a method for producing it. SOLUTION: As to the hot dip galvannealed steel sheet, having a hot dip galvannealing layer obtd. by hot-dip plating the surface of a steel sheet contg., as components in the steel, by weight, 0.2 to 3% Si and 0.1 to 10% Mn with an alloy essentially consisting of Mg and zinc and thereafter executing alloying treatment under heating at 540 to 600 deg.C, 0.1 to 2% Mg, 0.01 to 3.0% Mn and 7 to 15% Fe are allowed to contain in the plating layer. As to the method for producing the hot dip galvannealed steel sheet, the surface of the steel sheet contg. Si and Mn is cleaned, thereafter, annealing is executed in a reducing or nonoxidizing atmosphere, and, subsequently, the steel sheet is passed into hot dip zinc contg. Mg without being brought into contact with the air and is moreover subjected to alloying treatment under heating at 540 to 600 deg.C.
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