COLD ROLLED STEEL SHEET HAVING EXCELLENT PHOSPHATE TREATABILITY AND SALT WARM WATER RESISTANCE AFTER COATING

摘要

PPROBLEM TO BE SOLVED: To provide a cold rolled steel sheet whose surface is provided with a prescribed amount of Ni flash plating, and which has excellent phosphate treatability and salt warm water resistance after coating. PSOLUTION: Regarding the cold rolled steel sheet in which the surface of a base steel sheet is provided with an Ni flash plating layer of 2 to 20 mg/mSP2/SP, a dipping electric potential difference Vo prescribed by the following formula (1) is 5 to 30 mV: Vo=E-Eo- - -(1), wherein, E: the electric potential at the time when the cold rolled steel sheet having the Ni flash plating layer is dipped into a solution; and Eo: the electric potential at the time when the cold rolled steel sheet after the removal of the Ni flash plating layer is dipped into the solution. PCOPYRIGHT: (C)2006,JPO&NCIPI