C17200 Beryllium Copper has extremely high hardness and ultimate tensile strength although the electrical conductivity is lower than the Class 3 copper. It is generally recommended as electrode material for special flash, flash butt and projection welding applications where pressures are extremely high and wear is severe but where heating is not excessive. It is available as wrought material for highest quality dies and electrodes and may also be obtained as high strength castings. It is used frequently in the forms of inserts and die facings, and may also be used for seam welder bushings. Class 4 copper is available in the annealed condition, in this state it can be more readily machined and may be subsequently heat treated to maximum hardness.
Copper Beryllium alloys derives their high strength through heat treament and,in the case of small cross section wroght forms, cold working. The amount of cold work and the type of heat treatment determine the alloy's properties. The combination of cold work and heat treatment define the alloy's temper.