Microstructure and texture evolution in a magnesium alloy during processing by high-pressure torsion

Huang, Yi; Figueiredo, Roberto B.; Baudin, Thierry; Helbert, Anne‐Laure; Brisset, François; Langdon, Terence G.

doi:10.1590/s1516-14392013005000025

Cited by 38 publications

(29 citation statements)

References 34 publications

(38 reference statements)

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“…The gauge lengths after tensile testing were measured using an Olympus BX51 microscope. The hardness values are consistent with the corresponding microstructure features at 296 K reported earlier [15][16][17][18] where the finer grain size at the disc centre and half-radius areas after 5 turns leads to higher hardness values than its counterpart processed by 1 turn and the similar ultrafinegrain sizes at the disc edge after 1 and 5 turns lead to similar hardness values. Figure 2 shows the microstructure before HPT processing and after 5 turns of room temperature HPT processing at the disc edge area.…”

Section: Experimental Materials and Proceduressupporting

confidence: 90%

An evaluation of high temperature tensile properties for a magnesium AZ31 alloy processed by high-pressure torsion

Huang¹,

Pereira²,

Figueiredo³

et al. 2015

LoM

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A magnesium alloy AZ31 was processed by high-pressure torsion (HPT) at room temperature. Microstructure investigations show the material has a grain size as fine as ~450 nm after 5 turns of HPT processing. X-ray texture measurements show most grains have the {0001} fibre, with their c-axis parallel to the HPT torsion axis. Tensile specimens were cut from HPT disc and pulled to failure over a range of strain rates (4.5×10 ) at temperatures of 623 and 673 K. The tensile elongations from HPT specimens are lower than for published results using equal-channel angular processing (ECAP) specimens although AZ31 has a finer grain size after HPT than after ECAP. The reasons for the lower elongations in HPT specimens are related to the thermal stability of the processed microstructure, the texture components and the tensile specimen size. Earlier investigations confirmed there was significant grain growth at 623 and 673 K in HPT samples, which would contribute to the low ductility of AZ31 in tensile testing. The main {0001} fibre in HPT samples means in tensile specimens most grains have their basal plane parallel to the surface of the tensile specimen, leading to the low ductility because the critical resolved shear stress does not operate on the basal plane due to the small Schmid factor that is nearly zero. The tensile specimen thickness in HPT is thinner than in ECAP and it is known that the ductility decreases when reducing the specimen thickness.Keywords: AZ31, high-pressure torsion, magnesium alloy, tensile properties Оценка высокотемпературных механических свойств при растяжении магниевого сплава AZ31, подвергнутого кручению под высоким давлениемМагниевый сплав AZ31 был подвергнут кручению под высоким давлением (КВД) при комнатной температуре. Ми-кроструктурные исследования показали, что материал имеет размер зерен около 450 нм после 5 оборотов КВД. Из-мерения текстуры рентгенографическим методом показали, что большинство зерен имеют волокнистую текстуру {0001} с осью c, параллельной оси кручения. Из дисков, подвергнутых КВД, вырезаны образцы для испыта-ний растяжением, которые испытаны до разрушения в интервале скоростей деформации (4.5×10 ) при температурах 623 и 673 K. Значения удлинения при растяжении образцов после КВД оказались ниже, чем опубликованные значения, полученные на образцах, подвергнутых равноканальному угловому прессованию (РКУП), хотя сплав AZ31 имеет меньший размер зерен после КВД, чем после РКУП. Причина более низких значений удлинения образцов после КВД связана с термической стабильностью микроструктуры, текстурными компонентами и размерами образцов для растяжения. Прежние исследования показали, что в образцах после КВД имеет место зна-чительный рост зерен при 623 и 673 K; это вызывает снижение пластичности сплава AZ31 при растяжении. Главная текстурная компонента {0001} в образцах после КВД означает, что в образцах для растяжения большинство зерен имеет ориентацию базальной плоскости, параллельную поверхности образца. Это также приводит к снижению пластичности, так как...

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Section: Experimental Materials and Proceduressupporting

confidence: 90%

An evaluation of high temperature tensile properties for a magnesium AZ31 alloy processed by high-pressure torsion

Huang¹,

Pereira²,

Figueiredo³

et al. 2015

LoM

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“…This shows that the grain size distributions in the ZK60 alloy tend to be heterogeneous for all conditions including after processing through 5 turns of HPT. Table 1 [20,[23][24][25][26][27]. At elevated temperatures the bimodal structure is generally associated with the formation of a necklace structure along the grain boundaries [19,32] but necklace formation was not present after processing at room temperature either in this study or in earlier investigations [25,33,34].…”

Section: Microstructural Evolutionmentioning

confidence: 60%

“…In addition, there are limited reports on the microstructural and textural evolution in hcp materials such as Mg [18][19][20] and Ti [21,22] alloys after processing by ECAP or HPT. Very recent studies examined the microstructural evolution in the ZK60 Mg alloy using optical and electron microscopy [23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Orientation imaging microscopy and microhardness in a ZK60 magnesium alloy processed by high-pressure torsion

Torbati-Sarraf

Sabbaghianrad

Figueiredo

et al. 2017

Journal of Alloys and Compounds

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An extruded ZK60 magnesium alloy was processed by high-pressure torsion (HPT) at room temperature for up to 5 turns under a constant compressive pressure of 2.0 GPa with a rotation speed of 1 rpm. This processing produced an average grain size of ~700 nm. The grain size distributions and textures were examined by electron backscatter diffraction (EBSD) and this revealed some multi-modality in the microstructure at different stages of straining with fractions of both coarse grains and ultrafine grains. EBSD analysis at the mid-radius positions of unprocessed and HPT-processed materials revealed a gradual evolution from a prismatic {101 ത 0} fiber to an ultimate basal {0001} fiber texture with the c-axis parallel to the normal direction.The majority of grain boundaries had misorientations larger than 15 o throughout the processing.The strain hardening tended towards a reasonable hardness homogeneity with a hardenability exponent, η, of 0.07 up to strains of ~20 and with a subsequent hardness saturation at Hv ≈ 125.

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“…11. The (00.2) pole figures of the extruded Mg processed by 1/8 turn of HPT exhibits double textures, which indicates the non-basal <c+a> slip is activated along with the basal slip [48,49 ].…”

Section: Deformation Mechanisms Of Mg During Hptmentioning

confidence: 99%

Hardening mechanism of commercially pure Mg processed by high pressure torsion at room temperature

Qiao

Zhao

Gan

et al. 2014

Materials Science and Engineering: A

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Microstructure and texture evolution in a magnesium alloy during processing by high-pressure torsion

Cited by 38 publications

References 34 publications

An evaluation of high temperature tensile properties for a magnesium AZ31 alloy processed by high-pressure torsion

An evaluation of high temperature tensile properties for a magnesium AZ31 alloy processed by high-pressure torsion

Orientation imaging microscopy and microhardness in a ZK60 magnesium alloy processed by high-pressure torsion

Hardening mechanism of commercially pure Mg processed by high pressure torsion at room temperature

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