| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide galvanized steel stock capable of improving the black discoloration resistance without degrading the corrosion resistance. <P>SOLUTION: The galvanized steel stock has a galvanized layer on a surface of the steel stock to be processed, and further has a chromate-free conversion coating film on the surface of the galvanized layer. The conversion coating film contains: at least one kind of first element to be selected from Si, P, As, S, Fe, Co, B, Ge, Mn, Cu and Zn; and at least one kind of second element to be selected from Mo, W, V and Nb; wherein the second element contained in the conversion coating film is present as heteropoly acid by the adhesion amount of ≥0.40×10<SP POS="POST">-5</SP>mol/m<SP POS="POST">2</SP>. <P>COPYRIGHT: (C)2012,JPO&INPIT |
