Estimation of Residual Stresses and Dislocation Densities of Strain Hardened Pure Copper Specimens using X-ray diffraction Technique

Author: Ananth Kandadai, Ph.D. Student in Materials Engineering and Science

Mentor: Dr. Bharat Jasthi, Department of Materials and Metallurgical Engineering

The residual stresses in metals are often associated with plastic deformation which results in the movement of dislocations and thus affects the mechanical and corrosion properties of the material. X-ray diffraction (XRD) is a non-destructive tool that can be used to estimate the surface residual stresses and dislocation densities in the material. In the present work, copper samples (99.99% pure) were annealed at 950°C for 1h in an argon atmosphere and cold rolled to 16%, 30%, and 55% reduction in thickness. The effect of cold rolling on residual stresses and dislocation densities was estimated using the XRD technique. The widely accepted sin²ψ method is used to estimate the residual stresses, and dislocation density measurements were estimated from the line broadening of XRD peaks using the Williamson-Hall (W-H) approach. The dislocation density and residual stress values of the cold-rolled specimens were compared with annealed copper and copper produced using the Czochralski process.

Keywords: X-ray diffraction, residual stress, dislocation density, Williamson-Hall analysis, copper, cold rolling