GMW17156

Description / Abstract: GMW17156, 2nd Edition, October 2019 - Black Oxide Finish

This specification covers black oxide finishes applied over iron and steel parts and 300 series stainless steel parts for decorative or identification purposes.

Material Description.

The finish is a magnetite type black oxide conversion layer produced by immersion of the part in a hot alkaline salt solution or mixed salt fusion bath.

Symbols.

Not applicable.

Applicability.

Black oxide is not generally used for 400 series stainless steel and offers little protection when applied over 200 series stainless steel parts. This finish offers little wear resistance, and no corrosion resistance unless accompanied by additional supplemental topcoat or oil.

Remarks.

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 this specification in the drawing as required.

The coating process may generate pitting and/or intergranular attack. The acceptable level of attack on the intended substrate material and application shall be determined before the start of production and documented.