scope:

This specification describes the basic requirements for mechanically deposited zinc and zinc-tin coatings on iron and steel substrates. The basic requirements may include: minimum plating thickness, plating surface treatments (e.g. trivalent chromium conversion coating), typical appearance, and salt spray resistance of either the base metal and/or the zinc plating to the appearance of corrosion products. All surface treatments and post treatments shall be hexavalent chromium free. 

The specification number shown in the title is a generic number for the different mechanical plating finishes. Table 1 shows the specification numbers to be used on the drawings and reflects the basic requirements of the specification. 

Drawing call out example: Mechanical Zinc-Tin Plating, DX551613 (12K1000/480T) per DX551600. 

This example from Table 1 indicates a mechanically deposited zinc-tin plating with a 12 micrometer minimum thickness that has a plating surface treatment and a clear Dipping solution with integrated lubrication having a coefficient of friction 0.13 ± 0.03 (±3 sigma). The coating must withstand a minimum of 1000 hours neutral salt spray without evidence of base metal corrosion (red rust) and a minimum of 480 hours neutral salt spray without evidence of zinc-tin corrosion products (white rust). The presence of a suffix after the specification number (example: DX551612-F) indicates an approved source supplemental qualification requirement, as described in Section 11. 

Specific requirements shown on the part drawing shall take precedence over any requirements in this specification, or may be in addition to the requirements of this specification. 

Some colors are typically obtained by the use of specific zinc surface treatments, post-treatments or color dyes. 

The use of zinc and zinc-tin plating and related finishes described in this specification on threaded surfaces and/or bearing surfaces of joints could affect the torque-tension relationship. It is recommended that a torquetension study of the fastener joint be performed before releasing the specified plating and finishes for use on new threaded applications. See Table 2 of this specification. 

Zinc plated parts or their corrosion products must not come in contact with stressed Polyamides 6 or 66.