PURPOSE: To provide a material having corrosion resistance over a long period of time by forming a zinc-based dispersion plating layer contg. specified rust preventive pigment particles and lubricant particles on a steel sheet by electroplating, forming a specified chromate coating film on the plating layer and further forming an org. resin coating film.
CONSTITUTION: A zinc-based dispersion plating layer is formed on a steel sheet by electroplating. This plating layer contains one or more kinds of rust preventive pigment particles of strontium chromate, barium chromate and lead chromate and one or more kinds of lubricant particles of silica, molybdenum sulfide, lead sulfide and barium sulfate. A chromate coating film based on hexavalent Cr and trivalent Cr is then formed on the plating layer and an org. resin coating film having 0.5-2.0μm thickness is further formed on the chromate coating film. A material excellent in corrosion resistance to an environment causing salt damage, press workability, weldability and adhesion of a coating material can be provided.
ISAKI TERUAKI
MIZUGUCHI TOSHINORI
