GMNA GM6173M PDF

This standard covers the basic requirements for a chromium-free corrosion protective coating system which is derived from the application of a water base solution containing uniformly dispersed zinc and aluminum platelets or flakes and proprietary inorganic materials. The coating can be top coated with a water base sealer compound to provide specific torque-tension properties. The sealer may be clear or colored. (black, blue, green, etc). Colors other than black however are for identification purposes only. Parts top coated with clear sealer shall have a bright metallic silver appearance. Parts to be top coated with a color pigmented sealer shall be specified (Example, GM6173M black).

These coatings are especially suitable for externally and internally threaded and nonthreaded ferrous parts which are not adversely affected by baking temperatures in the range of 290 to 325°C. Hydrogen embrittlement is not induced by this coating process. This finish is suitable for spring or other high hardness applications.

This coating system shall be completely free of hex chrome. The final product shall conform to the requirements of GMW3059. All the approved sources listed in MATSPC database (refer section 6 Approved Sources) shall be hex chrome free by July 2005.

This specification is intended for use on carry over parts only. Contact Materials Engineering before using this specification on any new designs.

Use of this finish on a threaded surface and/or on the bearing surface of joints could affect the torque-tension relationship. It is recommended that a torque-tension study of the fastener joint be performed before releasing this finish on a new application.