Bell Laboratories, Murray Hill, N.J.
The reversed bending fatigue properties of a Cu-9Ni-2Sn alloy, designated CA-725, were studied as they might be influenced by prior cold rolling and by the orientation of the normal stress with respect to the direction of rolling. The fatigue strength of this alloy was found to increase as a function of prior cold work for cold reductions ranging from 21 to 95 percent. In this respect this material is different from 5 percent tin phosphor bronze (CA-510) and 12 percent nickel silver (CA-762) for which no further improvement in fatigue strength is noted in the range of cold reductions 50–70 percent. For cold reductions greater than 37 percent (hard temper) the fatigue strength for material stressed at 90 deg to the direction of rolling is consistently higher than for material stressed in the parallel direction. This anisotropic effect becomes more pronounced with increasing prior cold work.
Paper ID: JTE10046J