Galvanized steel sheet and method of manufacturing the same

A method of manufacturing a galvanized steel sheet, the method comprising:

• a first process of casting a steel which includes, as a steel chemical composition, by mass %,
• C:
• 0.05 to 0.40%,
• Si:
• 0.5 to 3.0%,
• Mn:
• 1.5 to 3.0%,
• P:
• limited to 0.04% or less,
• S:
• limited to 0.01% or less,
• N:
• limited to 0.01% or less,
• Al:
• limited to 2.0% or less,
• O:
• limited to 0.01% or less, and
• the balance consisting of Fe and unavoidable impurities;
• a second process of heating the steel directly or after once cooled;
• a third process of hot rolling the steel so that the hot rolling is completed at a temperature of an Ar3 transformation point or higher;
• a fourth process of coiling the steel at 300° C. to 700° C.;
• a fifth process of pickling the steel;
• a sixth process of cold rolling the steel by a cold rolling mill having a work roll with a roll size of 1,400 mm or less with a cumulative rolling reduction of 30% or more and less than 100%;
• a seventh process of heating the steel and retaining the steel at 550° C. to 750° C. for 20 seconds or more;
• an eighth process of annealing the steel at 750° C. to 900° C.;
• a ninth process of cooling the steel to an intermediate cooling temperature in a temperature range of 500° C. or higher and lower than 750° C. at a first average cooling rate of 0.1° C./s to 30° C./s and cooling the steel from the intermediate cooling temperature to a cooling stop temperature of 100° C. or higher and lower than 350° C. at a second average cooling rate which is equal to or higher than the first average cooling rate;
• a tenth process of controlling a temperature of the steel within a temperature range of a temperature, which is lower than a plating bath temperature by 40° C., or higher and a temperature, which is higher than the plating bath temperature by 40° C., or lower;
• an eleventh process of galvanizing by immersing the steel into a hot dip galvanizing bath flowing at a flow rate of 10 m/min to 50 m/min;
• and
• a twelfth process of cooling the steel to a temperature of lower than 100° C.;
• wherein the second average cooling rate is 1° C./s to 100° C./s, and
• a time when the temperature of the steel is within a temperature range of 350° C. to 500° C. is 20 seconds or more in the processes after the ninth process.