Stress Relaxation in Beryllium Copper Strip

Abstract

A study was made of the stress relaxation of three beryllium copper alloys in strip form at temperatures between 20 and 200°C. The work was undertaken to obtain comprehensive stress relaxation data that would be useful in engineering design. A mandrel test method was chosen because many of the commercial applications in which stress relaxation is important concern strip material. Materials were stressed at levels of 50, 75, and 100 percent of the 0.2 percent offset yield strength for a total of 40 days. The results showed that aging greatly reduced the stress relaxation in beryllium copper alloys. There was no apparent dependence of stress relaxation on strip orientation. For comparative purposes, a number of tests were run on other copper spring alloys.