Determining Residual Stress in Copper by Nanoindentation in Compressive and Tensile Stress States

In this study, nanoindentation was employed to determine residual stresses in copper after compression and tension deformations with different deformation levels. Rectangular and cylindrical compression specimens were prepared in order to produce residual stresses parallel or perpendicular to the stress direction. For the compression deformation, with the increase in compressive strain, the residual compression stress parallel to the compression direction increased and exhibited a linear relationship with the compressive strain, σcompression resparallel=−1.56εrectangle compression, while the residual compression stress perpendicular to the compression direction were as follows: σcompression resperpendicular=−0.20εcylinder compression. For the tension deformation, with the increase in tensile strains, the residual tension stress parallel to the tension direction increased and exhibited a linear relationship with the tensile strain, σtension resparallel=1.03εplate tension, while the residual tension stress perpendicular to the tension direction were as follows: σtansion resperpendicular=0.65εcylinder tension. The residual stresses parallel to the stress direction exhibited significant anisotropic characteristics, while the residual stresses perpendicular to the stress direction exhibited significant isotropic characteristics. Based on the above results, the relationship between strains and residual stress were successfully determined, providing valuable data reference for engineering applications.