Developing methods of constrained groove pressing technique: A review

Abstract

Among various severe plastic deformation (SPD) techniques, constrained groove pressing (CGP) has arisen as a famous technique for fabricating ultrafine-grained sheet metals and alloys in recent times. The severe strain is applied to improve the mechanical performance and properties. However, inhomogeneous grain refinement, lower formability, surface unevenness, and microcracks are the common limitations of conventional CGP-processed samples. Therefore, this review inspects the latest progress through modifications of the CGP process and compares the process efficacy with the conventional process. Advanced CGP processing techniques, such as modification of die design, annealing of the processed sample, cross CGP, ring CGP, hybrid SPD, covered sheet casing CGP, and rubber pad CGP, are emerging techniques to up-scale the procedure and improve the grain refinement and thereby produce superior mechanical properties. In this review paper, the historic research of conventional CGP and its effect on grain refinement and mechanical properties is initially briefed and then recent progress through different advanced techniques is highlighted, especially in alloys. Albeit significant progress has been observed in CGP, the future scope and successful usage of CGP-processed samples in actual practice are discussed in the last stage.

Re-examination and comparison of activation volume, strain rate sensitivity, and dislocation density for coarse grain and CGP-processed UFG materials

“…The chemical composition (in wt%) of low-carbon steel is 0.22% of Mn, 0.04% C, 0.04% Al, 0.01% P, and balance Fe. The procedure of CGP process is discussed in many literature 5,6,8,36 and the groove die setup used in this work is given in reference. 4 The low-carbon steel sample is successfully processed for five CGP passes but the surface defects like microcracks and unevenness are observed after three passes onwards.…”

“…, the engineering-based strain rate sensitivity 1 m can be derived by linear fitting of equation (8).…”

“…7 Moreover, inhomogeneous grain refinement, sheet defects like surface unevenness and cracks, and lower grain refinement are the common limitations in the CGP process. 5,8 Apart from CGP, inhomogeneous grain refinement is always present in all the SPD processes though it is lower in the last passes. 9 Sometimes highly distorted microstructure, which is difficult to analyze optically, 10 is observed due to a large strain imposed during the process.…”

“…7 Moreover, inhomogeneous grain refinement, sheet defects like surface unevenness and cracks, and lower grain refinement are the common limitations in the CGP process. 5,8…”

Strength enhancement and uniform strain distribution through cross route-constrained groove pressing

“…The metal undergoes significant plastic strain in all SPD processes without altering its shape. Equal channel angular pressing (ECAP) [9], accumulative roll-bonding (ARB) [10], high-pressure torsion (HPT) [9], repetitive corrugation and straightening (RCS) [11], multi-axial forging (MAF) [12], asymmetric rolling (ASR) [13], and constrained groove pressing (CGP) [14] are among the SPD techniques available. ECAP, HPT, and MAF are capable of producing small-size samples through a discontinuous route in the processing of 2 bulk metals.…”