| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method of stably producing a hot dip galvannealed steel sheet which has excellent slidability on press forming. <P>SOLUTION: In the method, a steel sheet is subjected to hot dip galvanizing, is further alloyed by heating treatment, is subjected to skinpass rolling and is thereafter brought into contact with an acid solution to form an oxide layer on the surface of the plating, so that a hot dip galvannealed steel sheet is produced. The acid solution having a pH buffer action is used in the method. Further, after the steel sheet is brought into contact with the acid solution and is subsequently held for 1 to 30 s, water washing is performed. The acid solution having a pH buffer action has a degree of increase in pH in the range of 3.0 to 20.0 which is defined by the amount (ml) of a 1.0 mol/l sodium hydroxide solution required for increasing the pH of 1 L of the acid solution from 2.0 to 5.0. <P>COPYRIGHT: (C)2004,JPO</p> |
