GMW11 (J)

Description / Abstract: This standard covers the requirements for both one and two side pure zinc and zinc nickel alloy electrogalvanized coatings. These coatings are applied to a sheet steel substrate utilizing an electroplating process. The substrate may be either cold or hot rolled low carbon, rephosphorized, solid solution strengthened, bake-hardenable, high strength low alloy or dual phase steel. Additional requirements or agreements shall be specified by the local business units (e.g., NAO, Opel ITDC, GM do Brazil, Holden Ltd., etc.)

Material Description. The type of coating and its mass and finish are specified by suffixes added to the basic specification number. The first two letters EG will designate an electrogalvanized coating. The coating mass for each side is designated by a minimum value in g/m². Only coating masses of 47 g/m², 60 g/m² or 70 g/m² for pure zinc, and 32 g/m² for zinc-nickel alloy should be used unless materials engineering is consulted. Other coating masses shall follow the same designation method. For one side coated coils, or sheets/blanks the uncoated side should be free of coating. A residue of 40 mg/m² max. is permissible. The letter G designates a pure zinc coating. The letter N designates a zinc-nickel alloy coating. The first set of digits along with the letter designation specifies the coating parameters of the unexposed side. The remaining designation specifies E (exposed), or U (unexposed) to depict surface finish.