METHOD FOR MANUFACTURING HIGH STRENGTH HOT-DIP GALVANIZED STEEL SHEET

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing a high strength hot-dip galvanized steel sheet using a high-strength steel sheet including Si and Mn as a base material and excellent in plating adhesion and corrosion resistance.SOLUTION: The method for manufacturing a high strength hot-dip galvanized steel sheet comprises: performing oxidation treatment to a steel sheet containing Si and Mn so that an average heating rate of the steel sheet is 20°C/sec or more, and a maximum arrival temperature T is 400-500°C in an area having an oxygen concentration of less than 1 vol% in the atmosphere; performing oxidation treatment so that an average heating rate of the steel sheet is less than 10°C/sec, and the maximum arrival temperature T is 600°C or more in an area having an oxygen concentration of 1 vol% or more in the atmosphere; performing reduction annealing and hot-dip galvanizing treatment; and performing alloying treatment by heating the steel sheet for 10-60 seconds at a temperature of 460-600°C.