Effect of strain path on microstructure and mechanical properties of AZ31 magnesium alloy sheets processed by constrained groove pressing

J Biomedical Materials Res

Chakkingal

et al. 2023

Biodegradable metals are important for temporary implant applications. However, poor mechanical properties and higher degradation rate of Mg and its commercial alloys is a major disadvantage. In this study, the above properties were tailored using the groove pressing (GP) technique. Uniform fine-grained (UFG) pure Mg and ZE41 alloy were obtained using GP technique. The impact of GP-induced microstructural changes and surface characteristics on mechanical performance, degradation behavior, biomineralization, surface wettability, and cytocompatibility were investigated.The groove-pressed pure Mg and ZE41 alloy had grain sizes of approximately 30 ± 7.8 and 25 ± 7.5 μm, respectively. The hardness of groove-pressed pure Mg and ZE41 alloy increased by 40% and 26%, respectively, when compared to the annealed condition. Enhanced strength and elongation were observed with these samples. The potentiodynamic polarization test showed a higher E corr and lower I corr values for groove-pressed sample when compared to the annealed condition indicating decreased degradation rate. The weight loss data from immersion tests also show that the degradation rate decreases with time confirming the surface passivity of the sample. The degradation rate decreased by 37% and 44% in simulated body fluid for pure Mg and ZE41 alloy, respectively, after GP. The higher hydroxyapatite deposition on the groove-pressed sample than the annealed sample, as observed from surface morphology studies after immersion in simulated body fluid, confirms the increased biomineralization tendency after GP. The higher wettability of the groove-pressed sample leads to higher cell adhesion and cell viability when compared to the annealed sample indicating higher biocompatibility.

Section: Discussionmentioning

confidence: 99%

“…It has been reported that during GP, the increased dislocation density lead to the sub-grain formation, and at the same time the dynamic recrystallization also occurs because of strain at high temperature. 25,42,43 It has been reported that the presence…”

Section: Discussionmentioning

confidence: 99%

Influence of fine‐grained structure produced by groove pressing on the properties of pure Mg and commercial ZE41 alloy

Sahu

J Biomedical Materials Res

Chakkingal

et al. 2023

“…92 The strain path slightly improves the grain refinement but modifies the texture of the processed sample. 36 Figure 18 illustrates the amount distribution of grain size and band contrast maps from EBSD microstructural analysis. A bimodal structure in the UFG magnesium alloy is observed due to dynamic recrystallization in all CGP routes.…”

Section: Advanced Developing Processes Of Cgpmentioning

confidence: 99%

“…Figure 18. The EBSD analysis of grain size distribution with band contrast maps (a) at the initial condition, (b) after one pass Route-1, (c) after two passes Route-1, (d) after Route-2, and (e) after Route-3 36. …”

mentioning

confidence: 99%

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.

“…Route-2 is an effective method for producing UFG structures in AZ31-O samples, and Route-3 imparts the same amount of strain in fewer passes and produces higher thinning of the sample [15]. Although the strain path slightly improves the grain refinement, it modifies the texture of the processed sample [17]. The distribution of grain size and band contrast maps from electron backscatter diffraction (EBSD) microstructural analysis shows a bimodal structure in the UFG magnesium alloy due to dynamic recrystallization in all CGP routes.…”

Section: Introductionmentioning

confidence: 99%

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

IOP Conf. Ser.: Mater. Sci. Eng.

2023

Constrained groove pressing (CGP) is one of the severe plastic deformation techniques for sheet metals to impose large plastic strain and produce ultrafine-grained (UFG) structures without any change in dimensions. Cross route-constrained groove pressing (Cross-CGP), an advanced version of the conventional CGP process, involves two CGP cycles with an equivalent strain of 2.32 per cycle where the square sample is rotated by 90° after performing every cycle of CGP. The strain path in the sheet during conventional CGP and cross-CGP significantly affects the homogenization of mechanical properties. Sheets of low carbon steel are processed through conventional-CGP and cross-CGP routes. The ability to sustain the maximum strain has been increased in the cross-CGP process due to uniform strain distribution. The tensile strength and hardness in the sheet processed through cross-CGP are higher than that of conventional CGP, especially at higher pass numbers. Tensile behavior and hardness in two different orientations (parallel and perpendicular to the groove direction) have been found to be almost the same in the cross-CGP processed sheet.