EBSD characterization of repetitive grain refinement in AZ31 magnesium alloy

Fatemi-Varzaneh, S.M.; Zarei-Hanzaki, A.; Cabrera, J.M.; Calvillo, Pablo Rodríguez

doi:10.1016/j.matchemphys.2014.10.026

Cited by 27 publications

(9 citation statements)

References 29 publications

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“…Generally, DDRX, also known as conventional DRX, takes place in cubic metals with low or medium stacking fault energy [52,53], and it features nucleation by grain boundary bulging followed by growth of the recrystallized grains [54,55]. However, grain boundary bulging needs developing subgrains near the pre-existing grain boundaries in order to provide the driving force required for local migration of the grain boundary [56].…”

Section: The Role Of Deformation Parametersmentioning

confidence: 99%

Dynamic recrystallization mechanisms and twining evolution during hot deformation of Inconel 718

Azarbarmas

Aghaie-Khafri

Cabrera

et al. 2016

Materials Science and Engineering: A

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202

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The hot deformation behavior of an IN718 superalloy was studied by isothermal compression tests under the deformation temperature range of 950–1100 °C and strain rate range of 0.001–1 s-1 up to true strains of 0.05, 0.2, 0.4 and 0.7. Electron backscattered diffraction (EBSD) technique was employed to investigate systematically the effects of strain, strain rate and deformation temperature on the subgrain structures, local and cumulative misorientations and twinning phenomena. The results showed that the occurrence of dynamic recrystallization (DRX) is promoted by increasing strain and deformation temperature and decreasing strain rate. The microstructural changes showed that discontinuous dynamic recrystallization (DDRX), characterized by grain boundary bulging, is the dominant nucleation mechanism in the early stages of deformation in which DRX nucleation occurs by twining behind the bulged areas. Twin boundaries of nuclei lost their ¿3 character with further deformation. However, many simple and multiple twins can be also regenerated during the growth of grains. The results showed that continuous dynamic recrystallization (CDRX) is promoted at higher strains and large strain rates, and lower temperatures, indicating that under certain conditions both DDRX and CDRX can occur simultaneously during the hot deformation of IN718.Peer ReviewedPostprint (author's final draft

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Section: The Role Of Deformation Parametersmentioning

confidence: 99%

Dynamic recrystallization mechanisms and twining evolution during hot deformation of Inconel 718

Azarbarmas

Aghaie-Khafri

Cabrera

et al. 2016

Materials Science and Engineering: A

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202

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“…It is noteworthy that the average grain size can be refined down to $ 2 μm in HSEM at the ambient temperature of 293 K by a single pass of deformation process, which is comparable to the value of 2 μm after four-pass ABE at the temperature of 503 K [15] and is even less than that of 5.5 μm for AZ31 alloy produced by eight-pass ECAP at the temperature of 523 K [17]. Jorge et al processed AZ31 alloy by ECAP under conditions of temperature and numbers of passes in order to avoid grain growth [37].…”

Section: Microstructure Measurementsmentioning

confidence: 59%

“…4b-d) due to the complete DRX. During the complete DRX, the dislocations that generate due to SPD are incorporated by the transformation of low angle boundaries (LABs) to high angle boundaries (HABs) [15]. The complete DRX in chips with small chip thickness ratio may absorb the dislocations which are emitted due to large strain in HSEM, thus, the Vickers hardness does not increase any more though the grains are homogeneously refined down to 2 μm.…”

Section: Hardness Measurementsmentioning

confidence: 99%

“…Conventional SPD techniques such as equal channel angular pressing (ECAP) [12], high pressure torsion (HPT) [13], accumulative roll bonding (ARB) [14] and accumulative back extrusion (ABE) [15,16] are able to vary the grain size and grain boundary distribution, thus conferring the microstructure significantly different properties. However, in these conventional SPD techniques, multiple passes of deformation process are needed to accumulate large strain in materials, and suitable route and temperature are also necessary in order to refine the microstructure down to ultrafine-grain [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

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A new method for grain refinement in magnesium alloy: High speed extrusion machining

Liu

Cai

Dai

2016

Materials Science and Engineering: A

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a b s t r a c tMagnesium alloys have received broad attentions in industry due to their competitive strength to density ratio, but the poor ductility and strength limit their wide range of applications as engineering materials. A novel severe plastic deformation (SPD) technique of high speed extrusion machining (HSEM) was used here. This method could improve the aforementioned disadvantages of magnesium alloys by one single processing step. In this work, systematic HSEM experiments with different chip thickness ratios were conducted for magnesium alloy AZ31B. The microstructure of the chips reveals that HSEM is an effective SPD method for attaining magnesium alloys with different grain sizes and textures. The magnesium alloy with bimodal grain size distribution has increased mechanical properties than initial sample. The electron backscatter diffraction (EBSD) analysis shows that the dynamic recrystallization (DRX) affects the grain refinement and resulting hardness in AZ31B. Based on the experimental observations, a new theoretical model is put forward to describe the effect of DRX on materials during HSEM. Compared with the experimental measurements, the theoretical model is effective to predict the mechanical property of materials after HSEM.

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“…In recent years, many papers investigated the recrystallization behaviours in SPD [69,[122][123][124][125]] so as to understand its underlying grain refinement mechanism. Not surprisingly, different mechanisms have been observed.…”

Section: Introductionmentioning

confidence: 99%

High toughness magnesium alloy through severe plastic deformation and short annealing

Fong¹

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This thesis represents a body of work that was achieved with the assistance, guidance and support of several people. I consider it an immense privilege to have worked with them. First of all, I would like to express my sincere gratitude to my supervisor, Prof. Tan Ming Jen for his kind guidance, critique, support and encouragement throughout my PhD study. I am also grateful to my co-supervisor and team leader, Dr Chua Beng Wah for his support, motivation and providing me with the framework and freedom in pursuing my research. It has been interesting working under their supervisions which benefited me not only in my research and also in my personal life. I am greatly thankful for all professional support and help I received from Dr Danno Atsushi in SIMTech. His tireless support at the beginning of and during my research had helped me to shape my research outcome. I am very grateful to have the opportunity to collaborate with Dr

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EBSD characterization of repetitive grain refinement in AZ31 magnesium alloy

Cited by 27 publications

References 29 publications

Dynamic recrystallization mechanisms and twining evolution during hot deformation of Inconel 718

Dynamic recrystallization mechanisms and twining evolution during hot deformation of Inconel 718

A new method for grain refinement in magnesium alloy: High speed extrusion machining

High toughness magnesium alloy through severe plastic deformation and short annealing

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