Analytical development and experimental verification of empirical correlations to determine mechanical properties of copper alloys using small punch test data

Abstract

Abstract The objective of the present work is to develop improved correlations to calculate yield and ultimate stresses of copper alloys using small punch test (SPT) data. Copper and its alloys are used in particle-accelerator and fusion-reactor components beside having other applications. Advanced copper alloys are sufficiently attractive to consider in fusion reactor application as primary structural materials. Safety of such mega nuclear facilities are affected due to aging of copper alloys with the service life, such as irradiation. The degradation of mechanical properties need to be assessed using limited quantity of aged materials. Small punch tests are useful to meet such purpose. It is found that the existing correlations in literature to determine yield and ultimate stresses from small punch test data are primarily developed for structural steels. Their applicability for copper alloys needs to be ascertained. To develop such correlations exclusively for copper alloys, the mechanical properties of fourteen copper alloys are taken from literature. The range of mechanical properties of this set of copper alloys meet the requirements of most of the commercial copper alloys of general interest. Finite element analyses are carried out to obtain load-displacement data of small punch test specimen for each material separately. Two new correlations are developed by plotting computed yield load against yield stress and ultimate load against ultimate stress. Small Punch Test specimens are then fabricated and tested for two widely used copper alloys. The experimental data is then used to verify the newly developed correlations. A comparison of new correlations with the other existing correlations in literature is also presented. Such correlations also can be used to calculate changes in yield and ultimate stresses with the service life conducting small punch tests of such aged materials.