PURPOSE: To embody thin coating weight and high corrosion resistance without limiting steel components in a base steel sheet even under a severe environment as a rust preventive steel sheet for automobile.
CONSTITUTION: A Ni-P alloy plated layer containing 8-15wt.% P is formed on the surface of the steel sheet and the steel sheet formed with the Ni-P alloy plated layer is heat treated in a non-oxidizing atmosphere after cold rolled to form a diffused alloy zone mainly containing Fe-Ni-P between the base steel sheet and the plated layer. After that, the rust preventive steel sheet having thin coating surface density and high corrosion resistance is produced by galvanizing or Zn-electroplating an alloy or dispersed particles of Zn as a matrix and one or more kind of metals or the oxides of Ni, Fe, Co, Cr, Mn, Ti, Mo and Si.
ABE MASAKI
WATANABE TOYOFUMI
SHIOBARA YUKIMITSU
