PURPOSE: To produce a Zn-Mg alloy plated steel sheet in which the content of Mg is prescribed by specifying the molar ratio of zinc chloride to magnesium chloride in a chloride molten salt and the current density in electrolysis at the time of producing a Zn-Mg electroplated steel sheet by using the chloride molten salt.
CONSTITUTION: In a plating bath constituted of a chloride molten salt bath, a steel sheet is subjected to cathode electrolysis at ≤200A/dm2 current density so as to regulate NZ/NM, i.e., the molarity NZ of zinc chloride and the molarity NM of magnesium chloride in the molten salt bath to 0.001 to 0.5. At this time, preferably, the plating bath is mixed with alkali metals (lithium chloride and potassium chloride), and the bath temp. is regulated to about ≤500°C. Thus, the Zn-Mg alloy plated steel sheet contg. ≥85wt.% Mg can be obtd.
NAKAKOUJI NAOMASA
NAKAJIMA SEIJI
MOCHIZUKI KAZUO
