Change in intragranular misorientation during stress relaxation behavior in Cu-Ni-Si alloy subjected to continuous cyclic bending

Abstract

Stress relaxation resistance is often required in application of electrical parts for copper and its alloys. The stress relaxation behavior should be influenced by stored strain through manufacturing process. In the present study, a Cu-Ni-Si alloy solution-treated sheet was subjected to continuous cyclic bending (CCB), which was proposed as a useful straining technique to impose higher strain on the surface and lower strain in the center layer of metal sheets. Samples were analyzed by scanning electron microscope / electron back scatter diffraction (SEM/EBSD) technique to investigate stored strain and stress relaxation process. CCB raised up the strength of Cu-Ni-Si alloy sheets at room temperature. The stress relaxation ratios of the CCBent sheets increased with an increment of test exposure time at 423K. The stress relaxation process was accompanied with change in intragranular misorientation of the samples. Change in intragranular misorientation through the stress relaxation test was understood as a result of release of residual and applied stresses with consumption of stored strain.