Improvement in residual stress distribution through cross-constrained groove pressing route

The uniform residual stress distribution in sheet metals of pure aluminum and low carbon steel after the Constrained Groove Pressing (CGP) process depends on the route and strain path change. CGP-processed samples up to two passes of both materials are characterized for residual stresses through experimental and numerical analysis. Since the strain distribution is not uniformly imposed during the CGP process, the inhomogeneous microstructure and residual stress distribution are observed through conventional CGP and henceforth the cross-CGP process is adopted. The residual stresses are measured using destructive contour and non-destructive X-ray diffraction methods in transverse and through-thickness directions. The residual stresses with continuous variation are compressive and tensile types at the surface and center of CGP samples respectively. For the sake of comparison, the methodology is verified by both the methods under conventional and cross-CGP routes. The uniform residual stresses are observed in the transverse direction in both CGP routes. However, the uniform residual stresses in the through-thickness direction are only observed in the cross-CGP processed sample in comparison to conventional CGP. The characteristics of uniform residual stresses can become advantageous for industrial applications by improving the service life. The numerical results confirm the experimental results from contour and x-ray diffraction methods.