Silver plating is very soft and has very low shear strength, and so acts as a solid lubricant, lowering the coefficient of friction where it is used dry. This means that less torque is required to produce a given level of preload, and this means that a stress is induced in the fastener during tightening. Silver also has the advantage in that it doesn't oxidise significantly at temperature, making it ideal for exhaust use.
Silver-plated nuts are used in some applications where high loads make it difficult for lubricants to remain in highly loaded parts of the contact. In these instances a low-shear strength coating such as silver can be beneficial.
Technical Characteristics Data MRC Criteria Characteristic BZRR THREAD SERIES UNF CQJX NOMINAL THREAD SIZE 0.375 INCHES CMLP THREAD QUANTITY PER INCH 24 AAJD THREAD CLASS 3B AAJF THREAD DIRECTION RIGHT-HAND MATT MATERIAL STEEL CORROSION RESISTING OVERALL SFTT SURFACE TREATMENT SILVER OVERALL CQFM HARDNESS RATING NOT RATED ACTA NUT STYLE A12 HEXAGON ADEA NUT HEIGHT 0.453 INCHES NOMINAL ASDB WIDTH ACROSS FLATS 0.563 INCHES NOMINAL AAUM LOCKING FEATURE CASTELLATED AZKQ TEMP RATING 550.0 DEG FAHRENHEIT NOMINAL PRMT III PRECIOUS MATERIAL SILVER