METHOD FOR MANUFACTURING HIGH STRENGTH GALVANIZED STEEL SHEET AND HIGH STRENGTH GALVANIZED STEEL SHEET (AS AMENDED)
First Claim
1. A method for manufacturing a high strength galvanized steel sheet having a zinc coating layer with an amount of deposition of coating of 20 to 120 g/m2 per one surface on the surface of a base steel sheet having a chemical composition comprising C:
- 0.03% to 0.35%, Si;
0.01% to 0.50%, Mn;
3.6% to 8.0%, Al;
0.001% to 1.000%, P≦
0.10%, S≦
0.010%, and the balance comprising Fe and incidental impurities, on a percent by mass basis, the method comprising the step of subjecting the base steel sheet to annealing and galvanization treatment in a continuous galvanizing line, whereinthe maximum steel sheet temperature in an annealing furnace is 600°
C. or higher and 750°
C. or lower, andthe steel sheet transit time in a temperature region of the maximum steel sheet temperature of 600°
C. or higher and 750°
C. or lower is specified to be 30 seconds or more and 10 minutes or less, and the dew point in an atmosphere is specified to be −
10°
C. or higher.
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Accused Products
Abstract
A method for manufacturing a high strength galvanized steel sheet and a high strength galvanized steel sheet are provided. A high strength galvanized steel sheet having a zinc coating layer with an amount of deposition of coating of 20 to 120 g/m2 per one surface on the surface of a base steel sheet having a chemical composition comprising C: 0.03% to 0.35%, Si: 0.01% to 0.50%, Mn: 3.6% to 8.0%, Al: 0.001% to 1.000%, P≦0.10%, S≦0.010%, and the balance comprising Fe and incidental impurities, on a percent by mass basis, is produced. At this time, in annealing and galvanization treatment of the base steel sheet in a continuous galvanizing line, the maximum steel sheet temperature in an annealing furnace is 600° C. or higher and 750° C. or lower, the steel sheet transit time in a temperature region of the maximum steel sheet temperature of 600° C. or higher and 750° C. or lower is specified to be 30 seconds or more and 10 minutes or less, and the dew point in an atmosphere is specified to be −10° C. or higher.
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Citations
7 Claims
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1. A method for manufacturing a high strength galvanized steel sheet having a zinc coating layer with an amount of deposition of coating of 20 to 120 g/m2 per one surface on the surface of a base steel sheet having a chemical composition comprising C:
- 0.03% to 0.35%, Si;
0.01% to 0.50%, Mn;
3.6% to 8.0%, Al;
0.001% to 1.000%, P≦
0.10%, S≦
0.010%, and the balance comprising Fe and incidental impurities, on a percent by mass basis, the method comprising the step of subjecting the base steel sheet to annealing and galvanization treatment in a continuous galvanizing line, whereinthe maximum steel sheet temperature in an annealing furnace is 600°
C. or higher and 750°
C. or lower, andthe steel sheet transit time in a temperature region of the maximum steel sheet temperature of 600°
C. or higher and 750°
C. or lower is specified to be 30 seconds or more and 10 minutes or less, and the dew point in an atmosphere is specified to be −
10°
C. or higher. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- 0.03% to 0.35%, Si;
Specification