| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a galvannealed cold rolled steel sheet having a uniform galvannealed layer which has a good surface property using as a substrate a cold rolled steel sheet containing an easily oxidizable element in a large amount, and to provide a method for producing the same. <P>SOLUTION: The cold rolled steel sheet includes a chemical composition which contains, in mass%, 0.02% or more and 0.25% or less C, 0.01% or more and 2.5% or less Si, 0.5% or more and 3.5% or less Mn, 0.1% or less P, 0.01% or less S, 1.0% or less sol. Al, and 0.01% or less N. In the galvannealed layer, the mass per unit area is 10 g/m<SP POS="POST">2</SP>or more and 80 g/m<SP POS="POST">2</SP>or less; the alloying degree is 7 mass% or more and 16 mass% or less; and the distribution of plating thickness satisfies the formula: d<SB POS="POST">max</SB>/d<SB POS="POST">0</SB>≤2.5, wherein d<SB POS="POST">max</SB>is the maximum plating thickness; and d<SB POS="POST">0</SB>is the average plating thickness. <P>COPYRIGHT: (C)2012,JPO&INPIT |
