Chrome Moly Alloy Steel
Electroplated zinc is a relatively thin sacrificial coating commonly selected for dimensional control, general industrial protection and a clean appearance. A conversion coating and optional sealer or topcoat are normally used to influence corrosion resistance, colour and friction. Performance must be specified by coating designation and test requirement rather than by appearance alone.
ASTM F1941/F1941M covers electrodeposited coatings on threaded fasteners. The purchase order should identify the coating material, thickness or service condition, conversion coating, sealer and any required test. Always confirm the current edition and project-specific restrictions.
Electrocleaning, acid pickling and electroplating can introduce hydrogen. Because B7 is heat treated, the complete process route, hardness and embrittlement controls require engineering review. Baking is a risk-reduction control, not proof that every risk has been removed.
Topcoats and sealers alter friction, while coating thickness consumes thread allowance. Specify the nut or mating thread, gauging condition and target friction range when tightening performance is critical.
Primary reference: ASTM F1941/F1941M — electrodeposited coatings on mechanical fasteners.