| 摘要 |
PURPOSE: A method of manufacturing a galvannealed steel sheet with good workability and chipping resistance is provided. CONSTITUTION: In a method of manufacturing a galvannealed steel sheet, the method is characterized in that before coagulation of zinc, a galvanized steel sheet drawn up out of zinc bath containing Al 0.13-0.14 wt.% is rapidly heated by an induction heat furnace to inhibit the crystallization of zeta and gamma phase wherein electricity power ratio of lower zone to upper zone of the induction heat furnace is regulated to 2:1-4:1. After heat treatment in the induction heat furnace, galvannealed steel sheet is rapidly cooled to 30-50°C/sec to inhibit the growth of gamma phase.
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