Effect of Constrained Studded Pressing on the Microstructure and Residual Stresses for Producing Nanostructure Pure Copper Sheet

Kaykha, Mohamad Mahdi

doi:10.22034/cas.2024.456324.1039

Effect of Constrained Studded Pressing on the Microstructure and Residual Stresses for Producing Nanostructure Pure Copper Sheet

Document Type : Original Article

Author

Mohamad Mahdi Kaykha

Department of Mechanical Engineering, Faculty of Engineering, University of Zabol, Zabol, Iran

https://doi.org/10.22034/cas.2024.456324.1039

Abstract

Severe plastic deformation (SPD) have been established to produce ultrafine-grained and nanostructure materials. One of the newly introduced methods is the constrained studded pressing (CSP) technique. A limitation of the CSP process is the creation of surface cracks. The most essential factors affecting surface cracks are residual stresses. In the current research, residual stresses distribution was studied on copper sheet under CSP using the finite element method. In addition, for laboratory study, microstructure and residual stress evaluation were studied before and after applying the CSP method. The microstructures of the annealed and deformed copper sheets have been observing by an optical microscope. The grain size, dislocation density, and the residual stresses were tested using an X-ray diffraction. The average grain size decreased from 27 μm in the annealed sample to 11 μm in the first pass sample. In the 10th pass, the average grain size decreased to 750 nm. The smallest reduction in grain size was achieved after applying the first pass, but with the increase of the applied strain in the final pass, the highest dislocation density was created in the microstructure. Therefore, by increasing the density of dislocations and followed by dynamic recovery, it caused the largest decrease in grain size compared to other samples. The residual stresses were altered from +153.2 MPa for the annealed sample to -48.6 MPa in the 10th pass sample. According to this research, the application of more strains is directly related to the creation of compressive residual stresses and grain refinement.

Graphical Abstract