Fabrication of fine recrystallized grains and their mechanical property in HPT processed pure magnesium

Joshi, Mohit; Fukuta, Yuko; Gao, Si; Park, Nokeun; Terada, Daisuke; Tsuji, Nobuhiro

doi:10.1088/1757-899x/63/1/012074

Cited by 12 publications

(11 citation statements)

References 9 publications

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“…It is observed that the flow stresses of the material tested at the lowest strain rates increase after annealing. The decrease in elongation and increase in flow stress observed after annealing are in agreement with recent results for magnesium processed by HPT and annealed at 523 K for 3 s [27]. The flow stress decreases when testing at 373 K but all curves show significant hardening.…”

Section: Tensile Testingsupporting

confidence: 91%

“…This result is in agreement with the improved ductility with grain refinement reported in early experiments on magnesium [37] including an elongation of 230% in a sample with a grain size of ~1.2 µm [7]. Higher ductility was also reported in an HPT-processed magnesium tested at 10 -3 s -1 compared to its annealed counterpart [27].…”

Section: An Examination Of the Enhanced Ductilitysupporting

confidence: 90%

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Evidence for exceptional low temperature ductility in polycrystalline magnesium processed by severe plastic deformation

et al. 2017

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An investigation was conducted to examine the mechanical behavior and microstructure evolution during deformation of ultrafine-grained pure magnesium at low temperatures within the temperature range of 296 -373 K. Discs were processed by high-pressure torsion until saturation in grain refinement. Dynamic hardness testing revealed a gradual increase in strain rate sensitivity up to m ≈ 0.2. High ductility was observed in the ultrafine-grained magnesium including an exceptional elongation of ~360% in tension at room temperature and stable deformation in micropillar compression. Grain coarsening and an increase in frequency of grain boundaries with misorientations in the range 15°  45° occurred during deformation in tension. The experimental evidence, when combined with an analysis of the deformation behavior, suggests that grain boundary sliding plays a key role in low strain rate deformation of pure magnesium when the grain sizes are at and below ~5 µm.

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Section: Tensile Testingsupporting

confidence: 91%

Section: An Examination Of the Enhanced Ductilitysupporting

confidence: 90%

Evidence for exceptional low temperature ductility in polycrystalline magnesium processed by severe plastic deformation

et al. 2017

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“…The absence of a steady-state level indicates that the saturation level (which has been reported in many metals and alloys [4,56,64]) should appear at larger numbers of turns in this two-phase alloy. Moreover, the strain softening that was reported at large strains in pure Mg [55][56][57] is not seen in this alloy because of the suppression of recrystallization due to solute atoms. The microhardness levels after the HPT processing are 57-63 Hv, which are higher than that for the extruded rod (48 Hv).…”

Section: Resultsmentioning

confidence: 74%

“…Mg-Li alloys which have a high strength to weight ratio and are used for transportation systems, are among the candidates for superplastic hydroforming [53]. There are currently wide activities on SPD processing of Mg alloys (see a recent review in [54]) including a few reports on grain refinement in HPT-processed pure Mg [55][56][57] and Mg-Li alloys [58][59][60]. The occurrence of superplasticity was reported in an Mg-8%Li alloy after processing by equal-channel angular pressing (ECAP) [61,62].…”

Section: Introductionmentioning

confidence: 99%

Ultrafine-grained magnesium–lithium alloy processed by high-pressure torsion: Low-temperature superplasticity and potential for hydroforming

Matsunoshita

Edalati

Furui

et al. 2015

Materials Science and Engineering: A

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“…With the advent of UFG materials, discontinuous yielding and Lüders band deformation was observed in Al, [67] Cu, [68] Mg, [69] Ti [70,71] and alloys [68,72] in addition to austenitic steels. [73] Closely linked to this topic is the yield stress and its dependence on grain size.…”

Section: The Hall-petch Relationship For Ufg Materialsmentioning

confidence: 99%

The Strength–Grain Size Relationship in Ultrafine-Grained Metals

Balasubramanian

Langdon

2016

Metall Mater Trans A

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Metals processed by severe plastic deformation [SPD] techniques, such as equal-channel angular pressing [ECAP] and high-pressure torsion [HPT], generally have submicrometer grain sizes. Consequently, they exhibit high strength as expected on the basis of the HallPetch [H-P] relationship. Examples of this behavior are discussed using data on Ti, Al-Mg 1 and Ni. These materials typically have grain size above ~50 nm where softening is not expected. An increase in strength is usually accompanied by a decrease in ductility. High strength and ductility can be achieved simultaneously by imposing high strains to give both ultrafine grain sizes and a high fraction of high-angle grain boundaries. An example is presented for a cast Al-7% Si alloy processed by HPT. In some cases, SPD may produce a fine grain size but also lead to a weakening due to microstructural changes as in ECAP of an Al-7034 alloy and HPT of Zn-22% Al. In SPD-processed materials, grain boundary segregation and nanostructural features are present which may lead to higher strengths than those predicted by the H-P relationship in some alloys having nano grain sizes.

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Fabrication of fine recrystallized grains and their mechanical property in HPT processed pure magnesium

Cited by 12 publications

References 9 publications

Evidence for exceptional low temperature ductility in polycrystalline magnesium processed by severe plastic deformation

Evidence for exceptional low temperature ductility in polycrystalline magnesium processed by severe plastic deformation

Ultrafine-grained magnesium–lithium alloy processed by high-pressure torsion: Low-temperature superplasticity and potential for hydroforming

The Strength–Grain Size Relationship in Ultrafine-Grained Metals

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