| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing an alloyed zinc hot dip galvanized steel sheet in which the variation in mechanical properties is reduced. SOLUTION: The zinc hot dip galvanized steel sheet has a chemical composition containing, in mass%, 0.05 to 0.30% C, 0.01 to 2.0% Si, 0.08 to 3.0% Mn, 0.003 to 0.1% P, 0 to 0.07% S, 0.01 to 2.5% Al, 0 to 0.007% N, and the balance Fe and inevitable impurities, and the time and temperature for the alloying treatment are controlled according to the formula:Si+Al≥1.5×10<SP>-7</SP>×t<SP>0.75</SP>×(T-465)<SP>3</SP>+0.117 where t represents the total time (sec) for which the steel sheet is held at≥465(°C) when the plating layer on the steel sheet is alloyed, and T represents an average temperature T(°C) during the total time (sec) for which the steel sheet is held at≥465(°C) when the plating layer on the steel sheet is alloyed. COPYRIGHT: (C)2005,JPO&NCIPI
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