STRESS-RELAXATION IN BENDING OF COPPER-NICKEL-TIN ALLOY STRIP STRENGTHENED BY SPINODAL DECOMPOSITION

The stress-relaxation behavior of three copper-nickel-tin alloys strengthened by spinodal decomposition was studied in the temperature range 23 to 204°C (73 to 400°F). The alloys studied were Cu-4%Ni-4%Sn, Cu-9%Ni-6%Sn, and Cu-15%Ni-8%Sn. The resistance to stress relaxation of these alloys at temperatures of 121°C (250°F) and higher is shown to be significantly improved over that of fully precipitation-hardened CA172 (Cu-1.9%Be alloy, condition TH04), a material widely used for connectors and electrical springs requiring high strength at moderately elevated temperatures. Design data that permit an evaluation of spring performance for extended service life applications are presented for these alloys. © 1979 by the American Society for Testing and Materials.