GMNA GM4347M PDF

This specification covers black oxide finishes applied over iron and steel parts and 300 series stainless steel parts for decorative or identification purposes. It offers little wear resistance, and the corrosion resistance of the base metal is not improved by the finish. Black oxide is not generally used for 400 series stainless steel and offers little protection when applied over 200 series stainless steel parts. Protective oils and waxes may be applied over black oxide to improve resistance to corrosion, in which case the improvement is proportionally equal to the quality of the oil/wax. Oil and/or wax coating shall be specified as a suffix to specification if required. Example: GM4347M, Oil.