Study on stress relaxation behavior and mechanism of typical high strength and elasticity copper alloy

Stress relaxation performance is an important mechanical property of high-strength and high-elasticity copper alloys. This work selects Cu-3Ti and Cu-15Ni-8Sn alloys with good application prospects and regulates their mechanical properties through heat treatment. By combining numerical simulation and TEM analysis, stress relaxation studies under tensile and bending loads were conducted at different temperatures. The results show that as the temperature increases, the stress relaxation rate significantly accelerates, and Cu-3Ti alloy has better stress relaxation resistance. Precipitation strengthening is the main mechanism of its stress relaxation performance, while the discontinuous precipitation phase leads to a higher stress relaxation rate in Cu-15Ni-8Sn alloy at high temperature. Compared to the most widely used high-strength and high elasticity Cu-Be alloy, the advantage of stress relaxation performance of Cu-3Ti alloy is more obvious at high temperatures. Meanwhile, in response to the differences in stress relaxation performance under different load forms, considering the service load characteristics of high-strength and high elasticity copper alloy components, a stress relaxation behavior prediction model based on tensile stress relaxation load which can be used to predict the stress relaxation behavior under different load forms was constructed through numerical simulation.