Friction behaviour evaluation in beryllium–copper threaded connections

Beryllium–copper alloys present a combination of high tensile and compressive strength, high hardness, good thermal conductivity and high resistance to seizing and galling (conditions where metals begin to cold weld or bond under the joint influence of compressive stress and relative motion at temperatures far below the melting temperature). These properties make beryllium–copper an excellent choice for bearing and bushing applications. Objective of this paper is to report the results of experimental tests carried out in order to evaluate the friction behaviour of threaded joints with at least one element made of Cu–Be; the other element is made of Cu–Be, steel or aluminium. The analysis of the results enabled us to establish that a threaded connection where an element is made of Cu–Be and the other one of steel, dry or at most lubricated by mineral oil, shows very encouraging frictional properties and can be considered as a good substitute for the usual joints made of steel and lubricated with environmental dangerous compounds.