Full Description

This specification covers requirements for a corrosion resistant blackfinish over anelectrolytically deposited zinc-iron alloy, nickel alloy and/orzinc-nickel alloy substrate.

Material Description. This coating system shall be free of hexavalentchromate in final product perGMW3059 requirements. The plating shall be called out on the partdrawing per example shown inparagraph 7.

Typical Application. This coating is intended primarily for bulkprocessed small steel parts suchas bolts, screws and nuts used on exterior and interior visible parts(cosmetic applications). Thiscoating is especially suitable for internal drive (cross recess, 6lobed socket etc.) threadedfasteners and self drilling and tapping screws.

Remarks. Use of this coating system on threaded surface and/or bearingsurface of joints couldaffect the torque-tension relationship. It is recommended that atorque-tension study of thefastener joint be performed before releasing this finish on any newapplication.