Full Description

This specification covers the basic requirements for barrel or rackelectrodeposited zinc alloyplating over a ferrous substrate. Various alloy platings are coveredby this specification withsupplementary treatments. Table 1 lists the zinc alloy finishescovered by this specification.

Note: This finish is not recommended for applications where whitecorrosion is a cosmetic concern.

Material Description. To distinguish between alloys, the chemicalsymbol of the alloying elementmust be added as a suffix to the specification number to designate thealloy desired. This coatingsystem must be free of hexavalent chromium with no hexavalent chromiumper the requirements ofGMW3059.

Plating Composition. The percentage of alloying element present in thezinc alloy electrodepositdiffers for each of the zinc alloys. The concentration limits for thevarious alloys are shown inTable 1.

Accurate control of alloy composition and alloy ratios within thelimits given in Table 1 areessential for optimum corrosion resistance and plating performance.

Cross-Reference of Replaced Specifications.

Typical Application. Zinc alloy plating is especially suitable forsmall to medium ferrous partssuch as castings, stampings, clips, fasteners and other ferrous partswhere levels of corrosionprotection exceeding pure zinc are required. A suffix code G is to beused when specified onfasteners. Use of this finish on fasteners could affect thetorque-tension relationship. It isrecommended that a torque-tension study of the fastener joint beperformed before use of thisfinish on fasteners.

Zinc Alloy plated parts or their corrosion products must not come incontact with stressedPolyamides 6 or 66.