METHOD FOR CHEMICALLY CONVERTING STEEL MEMBER, METHOD FOR MANUFACTURING COATED STEEL MEMBER HAVING BEEN ELECTRODEPOSITION-COATED, AND COATED STEEL MEMBER

摘要

Provided is a coated steel member that has an excellent corrosion resistance in a weld zone. In manufacturing a coated steel member by weld joining steel plates together and then subjecting the thus obtained steel member to a chemical conversion treatment and electrodeposition coating, the chemical conversion treatment comprises a surface-conditioning treatment using a surface-conditioning agent that contains a zinc phosphate colloid, and a subsequent zinc phosphate treatment using a zinc phosphate-treating agent that has a fluorine concentration of 100 mass ppm or greater.