Effects of repetitive upsetting-extrusion parameters on microstructure and texture evolution of Mg–Gd–Y–Zn–Zr alloy

Zhang, Guanshi; Zhang, Zhimin; Li, Xubin; Yan, Zhaoming; Yu, Jianmin; Meng, Yingze

doi:10.1016/j.jallcom.2019.03.207

Cited by 57 publications

(18 citation statements)

References 25 publications

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“…It means that the large grains indeed resulted from the dynamic recrystallization and grain growth during HPT. Such dynamic recrystallization during SPD have also been observed earlier in other materials like titanium‐based, magnesium‐based, aluminum alloys, copper alloys, and nickel‐based superalloys . These large recrystallized grains are predominantly typical twins intersecting with each other.…”

Section: Resultssupporting

confidence: 75%

Faceting of Twin Grain Boundaries in High‐Purity Copper Subjected to High Pressure Torsion

et al. 2019

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The microstructure of high‐purity 5N5 copper processed by high pressure torsion (HPT) is studied. Close to the top and bottom surfaces of HPT disk, the 2–10 μm‐thick ultrafine‐grained layers with equiaxial grains and grain size of about 150 nm are formed. This grain size is typical for HPT of copper and its alloys. However, the remaining bulk layer in the HPT disk contained mainly elongated intersecting twins with high aspect ratio and length of up to 1 μm. These twin grain boundaries (GBs) are faceted. The geometry of the GB facets is analyzed using Σ3 coincidence site lattice (CSL). The Σ3 twins after HPT contained (100)CSL, (110)CSL, (010)CSL, and non‐CSL 9R facets, but not (120)CSL and (130)CSL facets. Earlier, the stability diagram for the Σ3 GB facets is experimentally constructed for the same 5N5 high‐purity copper. The comparison of the data with this diagram allows to estimate for the first time the effective temperature of pure copper during HPT processing at room temperature (RT): Teff = 920 ± 50 K. In other words, the HPT at RT results in Σ3 GB facets as if the sample is annealed at Teff = 920 ± 50 K.

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Section: Resultssupporting

confidence: 75%

Faceting of Twin Grain Boundaries in High‐Purity Copper Subjected to High Pressure Torsion

et al. 2019

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“…Furthermore, it should be noted that the maximum pole intensity (MPI) is increased from 8.2 for n = 5 to 17.6 for n = 10, and then decreased to 6.5 for n = 50, which indicates that increasing the revolutions can promote the texture weakening. This phenomena may be attributed to the new DRXed grains that have a more random orientation compared with their parent grains [ 15 ]. Moreover, the proportion of DRXed grains in region A shows a trend of decreasing first and then increasing with the increase of rotating revolutions, which is exactly the opposite to the change trend of MPI.…”

Section: Resultsmentioning

confidence: 99%

“…As we all know, the current severe plastic deformation (SPD) method is an efficacious way to refine grains and weaken texture during the thermal process. SPD methods mainly include high pressure torsion (HPT) [ 8 ], multi-directional forging (MDF) [ 9 ], accumulative roll-bonding (ARB) [ 10 ], accumulative back extrusion (ABE) [ 11 ], friction stir processing (FSP) [ 12 ], equal channel angular processing (ECAP) [ 13 ], differential speed rolling (DSR) [ 14 ], repetitive upsetting extrusion (RUE) [ 15 ], and so on. All of the above SPD methods can refine grains, weaken texture, and enhance the mechanical properties of the materials significantly.…”

Section: Introductionmentioning

confidence: 99%

An Investigation on the Microstructure and Texture of an AZ80 Cup-Shaped Piece Processed by Rotating Backward Extrusion

Che

Dong

et al. 2020

Materials

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The rotating backward extrusion (RBE) process, as a new severe plastic deformation (SPD) process, is based on conventional backward extrusion and rotation, which meets the requirement of modern industrial development with its high performance and production efficiency. However, there is little research on the microstructure evolution and texture modification of the RBE process. Thus, in this study, the effect of different rotating revolutions, e.g., n = 5, n = 10, and n = 50, on the microstructure and texture development for the RBE process based on the AZ80 magnesium (Mg) alloy were investigated at 653 K. The results disclose that the rotating revolution is an influencing processing parameter on the deformation of the RBE process. The grain refining ability is enhanced with the increase of the rotating revolutions, and the minimum grain size of the cup bottom, shearing zone, and cup wall can reach to 16.7 μm, 15.6 μm, and 13.0 μm, respectively, under the condition of n = 50. Furthermore, with the increase in the rotating revolutions, the microstructure of the alloy becomes more uniform and the proportion of dynamic recrystallization (DRX) is also increased. The maximum DRX fractions of the sample for the cup bottom and cup wall are 95.4% and 86.8%, respectively, at n = 50. The DRX mechanism of the RBE process is determined by the continuous DRX and discontinuous DRX. In addition, the texture can be significant weakened during the RBE process, especially at the cup bottom, where the maximum pole intensity can be reduced from 17.6 at n = 10 to 6.5 at n = 50, which can be attributed to the higher proportion of new DRXed grains whose orientations are more random compared with the deformed grains.

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“…However, due to the poor ductility of magnesium alloys at room temperature, the problems of a low finished product yield and the high cost of cold drawing tubes urgently need to be addressed. Hot plastic deformation is a common method that is beneficial to the metal flow of magnesium alloys, as well as refinement of the microstructure by the accumulation of strain, corresponding to the characteristics of uniform deformation and excellent mechanical properties [8][9][10]. Because ultra-thin walled tubes usually have a thickness of 0.2-1.0 mm, they require high uniformity and are difficult to fabricate, especially the hexagonal closed-packed structure of the Mg alloy, which could increase the difficulty of manufacturing.…”

Section: Introductionmentioning

confidence: 99%

Research on AZ80 + 0.4%Ce (wt %) Ultra-Thin-Walled Tubes of Magnesium Alloys: The Forming Process, Microstructure Evolution and Mechanical Properties

Yan

Fang

Lian

et al. 2019

Metals

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Ultra-thin-walled tubes of magnesium alloys have received more and more attention in producing precision components for medical devices. Therefore, thin-walled tubes with high quality are desperately needed. In this study, the process of multi-pass variable wall thickness extrusion was carried out on an AZ80 + 0.4%Ce Mg alloy with up to five passes—one-pass backward extrusion and four-pass extension—to fabricate the seamless thin-walled tube with an inside diameter of 6.0 mm and a wall thickness of 0.6 mm. The average grain size decreased from 46.3 μm to 8.9 μm at the appropriate deformation temperature of 350 °C with the punch speed of 0.1 mm/s. X-ray diffraction (XRD), optical microscope (OM), scanning electron microscopy (SEM), and the Vickers hardness (HV) tester were utilized to study the phases, microstructure, and hardness evolution. It can be observed that low deformation temperatures (240 °C and 270 °C) and low strain (1 pass extrusion and 1 pass extension) lead to twins that occupy the grains to coordinate deformation, and a slip system was activated with the accumulation of strain. The results of the Vickers hardness test showed that twinning, precipitation of second phases, twinning dynamic recrystallization (TDRX), and work hardening were combined to change the hardness of tubes at 240 °C and 270 °C. The hardness reached 93 HV after the third pass extension without annealing at 350 °C.

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Effects of repetitive upsetting-extrusion parameters on microstructure and texture evolution of Mg–Gd–Y–Zn–Zr alloy

Cited by 57 publications

References 25 publications

Faceting of Twin Grain Boundaries in High‐Purity Copper Subjected to High Pressure Torsion

Faceting of Twin Grain Boundaries in High‐Purity Copper Subjected to High Pressure Torsion

An Investigation on the Microstructure and Texture of an AZ80 Cup-Shaped Piece Processed by Rotating Backward Extrusion

Research on AZ80 + 0.4%Ce (wt %) Ultra-Thin-Walled Tubes of Magnesium Alloys: The Forming Process, Microstructure Evolution and Mechanical Properties

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