AIA/NAS 672-2012 pdf download PLATING, HIGH STRENGTH STEELS, CADMIUM
This specification outlines the procedures to be followed in the cadmium plating of fasteners and fittings fabricatedof non-corrosion resistant steel in the heat treat ranges of 180 ksi and higher, and is designed to produce parts inwhich hydrogen embrittlement is minimized.
This specification shall be applicable only on drawings and/or specifications wherein it is so noted.
REQUIREMENTS
Thickness
The minimum thickness of cadmium plate for fasteners shall be .0003 inch and the maximum thickness shall be0005 inch. For other parts, the minimum thickness shall be .0003 inch.
Holes, recesses and other areas where a controlled deposit cannot be normally obtained and which cannot betouched by a sphere .75 inches in diameter, shall not be subject to a thickness requirement, but shall showevidence of coating. There shall be no visible bare areas.
Material
The basis material shall be substantially free from flaws or defects that will be detrimental to the protective value ofthe plate.
Parts which have been machined, ground (except for thread major grinding), cold formed, or cold straightened afterheat treatment shall be stress relieved for two hours at a maximum temperature of 50° below the temperingtemperature specified in AMS2759 for the applicable Class A alloy steel. Parts shall be free from oil and greasebefore stress relieving.
Plating
The parts shall be plated only by the process listed herein
The cadmium deposit shall be smooth, fine grained, adherent and free from blisters, pits, nodules, indications ofburning and other visible defects, and shall be deposited directly on to the basis metal. Darkened plate in recessesshall not be cause for rejection. Superficial staining or discoloration resulting from rinsing or baking shall not because for rejection.
The auality of the cadmium plate shall be such that when a test specimen is subjected to the salt spray testspecified it shall fulfill the requirements of Paragraph 2.3.3.1. Test parts plated to a thickness of .0003 inch onsignificant surfaces shall withstand 96 hours of salt spray test.
The appearance of more than six corroded areas that are visible to the unaided eye, or of any corroded areas largerthan 1/16 inches in diameter, shall be cause for rejection. For purposes of this requirement, a corroded area isdefined as exposure or corrosion of the basis metal.
2.4 Preparation
2.4.1 Scale or oxide removal shall be by mechanical means only.
2.4.2 Vapor degreasing and/or anodic or soak alkaline cleaning shall be used for the removal of oil, grease or dirt.
2.4.2.1 When anodic or soak alkaline cleaning is used, parts shall be water rinsed.