CGP Process Effects on the Microstructure Evolution, Mechanical Properties and Corrosion Behavior of Al Alloys: A Review Study

Constrained groove pressing (CGP) is a prominent severe plastic deformation (SPD) method, favored over other SPD techniques due to its ability to induce high strains, its cost-effectiveness, and the lack of a need for advanced tooling or equipment. This paper presents the first comprehensive, simultaneous analysis of the fundamentals, influential parameters, corrosion and mechanical properties, and microstructural evolution of aluminum (Al) alloys processed via CGP. Overall, the study results demonstrated that the yield strength of various Al alloys increased several-fold during the initial CGP passes, while elongation decreased by 50% to 75%. Failure behavior in CGP-processed aluminum samples depends on the alloy system; brittle fracture was observed in the AA5052 alloy, whereas the ductile nature of the material was preserved in pure Al and the 6061 alloy. An investigation into the corrosion behavior of CGP-processed Al alloys revealed a non-monotonic relationship between the number of CGP passes and corrosion resistance. Corrosion resistance was found to depend on thermal conditions, surface micro-cracks, and the strain path, with the Cross-CGP path yielding superior corrosion resistance compared to the Conv-CGP path. The analysis identified the discontinuous, batch-oriented nature of the CGP process, cracking during high-pass processing, and non-uniform strain distribution as key limitations hindering industrialization. Finally, the paper offers recommendations for developing continuous processing methods, designing optimal alloys through precipitate engineering, and utilizing machine learning (ML) techniques to optimize CGP processes.