Microstructural Evolution and Mechanical Properties of Constrained Groove-Pressed 304 Austenitic Stainless Steel

Proceedings of the Institution of Mechanical Engineers, Part L:

2023

The frequently used metallurgical parameters such as activation volume, internal stress, strain rate sensitivity, and dislocation density are identified in ultrafine-grained (UFG) materials through erudite analytical relations. It is difficult to analyze such parameters optically since the material consists of highly distorted and inhomogeneous microstructure due to the large strain imposed during the constrained groove pressing (CGP) process. Hence, transient tests like stress relaxation tests are advantageous over the optical to use. Apart from the identification of parameters in low-carbon steel materials using uniaxial loading and stress relaxation tests, the relationship between the parameters is nobly investigated in as-received and UFG structure samples produced through the CGP process. In the relationship, the exponential-power law constitutive to describe the accurate stress–strain curves, identification of mobile and forest dislocation density during strain hardening, and exponential variation between grain size and activation volume are proposed. The replenishment or exhaustion of mobile and forest dislocation density significantly affects the metallurgical parameters during uniaxial tensile loading followed by stress relaxation testing. In this experimental and analytical work, the CGP process produces a UFG material that has lower activation volume and higher stress drop, mobile dislocation density, forest dislocations density, strain rate sensitivity, and internal stress.

Section: Resultssupporting

confidence: 61%

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

Proceedings of the Institution of Mechanical Engineers, Part L:

2023

“…Some researchers also tried to process alloys to improve their mechanical properties through CGP. Khakbaz and Kazeminezhad, 69 Moradpour et al, 60 Shahmirzaloo et al, 2 and Rahul et al 66,67 found enhanced properties of Al-Mn alloy, Al-Mg alloy, brass, and stainless steel materials, respectively. The variation in mechanical properties of many materials under the influence of CGP is shown in Table 2.…”

Section: Mechanical Propertiesmentioning

confidence: 98%

“…With increasing pass numbers, cell wall dislocation density continuously increases at a low rate and cell interior dislocation density reaches the saturation line. 64 Among CGP of alloys, Rahul et al 66,67 performed the simulations and experiments on 304 and 316 austenitic stainless steel up to two passes. A high fraction of low-angle grain boundaries with high dislocation density and low crystallite size are observed in the CGP-processed samples through X-ray diffraction (XRD), optical micrograph, and electron backscatter diffraction (EBSD) analysis.…”

Section: Grain Refinementmentioning

confidence: 99%

“…To simulate a real state of the CGP process, the combined 2D plane strain and plane stress conditions are suitable for accurate simulation. Like experiments, some researchers also tried to simulate metals and alloys such as 316 and 304 austenitic steel in, 66,67 H62 brass, 57 and low carbon steel. 82 The dies and sample are modeled as discrete rigid and deformable shell bodies respectively.…”

Section: Finite Element Simulationmentioning

confidence: 99%

See 1 more Smart Citation

Developing methods of constrained groove pressing technique: A review

Proceedings of the Institution of Mechanical Engineers, Part L:

2022

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.

“…The severe plastic deformation (SPD) technique is a top-down approach to produce ultrafine-grained (UFG) materials from their bulk state and have improved mechanical characteristics such as ultimate tensile strength and hardness, which makes them more applicable for structural applications. Several SPD processes have been used to develop UFG materials, such as multi-axial compression (MAC) 1 , accumulative roll bonding (ARB) 2 , equal channel angular pressing (ECAP) 3 , high-pressure torsion (HPT) 4 and constrained groove pressing (CGP) 5 . MAC is a repeated compression technique that develops large strains with relatively less loss of ductility in comparison to conventional deformation techniques.…”

Section: Introductionmentioning

confidence: 99%

Corrosion Behaviour of Multiaxial Compressed AlMgSi alloy

Roy

2021

Def. Sc. J.

Self Cite

In the present study, AlMgSi alloy was processed through multi-axial compression (MAC) to produce ultrafine-grained microstructure at room temperature. The AlMgSi alloys are widely used in automobile industries for making cylinder heads and brake disks etc. MAC was performed up to three cycles and showed improvement in mechanical properties. The impact of different strain levels upon microstructure changes is investigated using electron backscatter diffraction (EBSD). The average grain size reduced from an initial average grain size of ~ 124 to ~ 3 μm after completion of three cycles of MAC processing. Samples were tested for mechanical properties using uniaxial tensile test, hardness measurements, and corrosion. Tensile test results show a considerable increase in yield strength from ~90 MPa to ~249 MPa after 3 cycles of MAC. The average hardness value increased from 52 VHN to 90 VHN after 3 cycles of MAC. The corrosion resistance of MAC processed samples was found to decrease in comparison to solution-treated samples.