| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a high strength hot dip galvanized steel sheet having high strength, excellent in press formability and deep drawability and used for an automotive inner sheet or the like. SOLUTION: A steel slab having a compsn. contg., by weight, 0.001 to 0.01% C, 0.05 to 0.20% P, 1.0 to 4.0% Mn, 0.005 to 0.5% Mo, 0.5 to 2.5% Cu, 0.005 to 0.1% Al and 0.0005 to 0.003% B, contg. 2.0% Si, 1.3% Ni, 0.02% S and <=0.007% N and furthermore contg. one or more kinds among Ti: [(48/12)×%C+(48/14)×%N+(48/32)×%S] to 0.10%, 0.01 to 0.1% Nb and 0.01 to 0.1% V is subjected to hot rolling so as to regulate the hot rolling finishing temp. to the Ar3 transformation point or above, the average cooling rate after the finish rolling to >=20 deg.C/sec and the hot rolling coiling temp. to 450 to 650 deg.C. After cold rolling, it is hot dip galvanized in continuous galvanizing equipment so as to regulate the annealing temp. to 800 to 920 deg.C, the average rate from the annealing temp. to the precipitation treating temp. to 5 to 120 deg.C/sec, the recrystallization annealing temp. to 500 to 650 deg.C, its time to 0.5 to 5min and the inlet side temp,. to 500 to 550 deg.C.
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