| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a welded plated steel pipe having a chemical conversion coating excellent in all of weather resistance, water resistance, discoloration resistance and coating adhesion. <P>SOLUTION: The welded plated steel pipe is produced using an Al-containing Zn-based alloy plated steel sheet including 0.05-60 mass% of Al as a base sheet, and then a chemical conversion coating having a film thickness of 0.5-10 μm is formed on the external side surface of the welded plated steel pipe. The chemical conversion coating includes: a fluorine-containing resin containing 0.05-5 mass% of hydrophilic functional groups selected from the group consisting of a carboxyl group, a sulfonic acid group and the salts thereof, and 7-20 mass% of F atoms; and 0.1-5 mass% in terms of metal of a Group 4A metal compound relative to the fluorine-containing resin. <P>COPYRIGHT: (C)2012,JPO&INPIT |
