GMW GMW8 PDF

This standard covers the requirements for hot dip coatings, both galvanized and galvannealed, applied to a sheet steel substrate utilizing a continuous hot dip process. The substrate may be cold or hot rolled sheet steel. Additional requirements or agreements shall be specified by the local business units (e.g., NAO, Opel ITDC, GM do Brasil, 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 HD will designate a continuous hot dip coating. The coating mass for each side is designated by a minimum value in g/m². Only coating masses of 45 g/m² , 52 g/m² , 60 g/m², 70 g/m² or 90 g/m² shall be used unless Materials Engineering is consulted. Differentially coated products may be specified. Other coating masses shall follow the same designation method. The letter G designates a pure zinc coating (galvanized) and the letter A designates a zinc-iron alloy (galvannealed) 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), Z (semi-exposed) or U (unexposed).