An investigation of hardness homogeneity throughout disks processed by high-pressure torsion

Kawasaki, Megumi; Figueiredo, Roberto B.; Langdon, Terence G.

doi:10.1016/j.actamat.2010.09.034

Cited by 184 publications

(134 citation statements)

References 32 publications

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“…For example, in the early stage of straining high-purity (99.99%) Al exhibits a higher hardness at the center of the disk and this value decreases with increasing straining, until it reaches a homogeneous high hardness compared to the annealed condition. [31][32][33] Similar behavior was also reported in high-purity (99.99%) Zn [34] and pure (99.9%) Mg. [35] By contrast, some metals such as the Zn-22% Al eutectoid alloy and the Pb-62% Sn eutectic alloy show different behavior where the hardness decreases significantly with increasing straining and ultimately reaches a homogeneous or saturation hardness, that is, lower than in the annealed condition. [36] These three different types of hardening behavior may be effectively illustrated as in Figure 1, [37] where the separate models delineate hardening without recovery, hardening with subsequent recovery, and an overall weakening.…”

Section: Introductionsupporting

confidence: 65%

“…[30] In the second model, the strain hardens rapidly in the early stages of straining, then softens with rapid recovery to reach a lower saturation microhardness value. This model applies to some high purity metals such as Al, [31][32][33] Mg, [35] and Zn. [34] As shown in Figure 1a and b, both of these models have final saturation microhardness values, which lie above the annealed or as-received values.…”

Section: Discussionmentioning

confidence: 99%

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Effect of Initial Annealing Temperature on Microstructural Development and Microhardness in High‐Purity Copper Processed by High‐Pressure Torsion

et al. 2017

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The effect of the initial annealing temperature on the evolution of microstructure and microhardness in high purity OFHC Cu is investigated after processing by HPT. Disks of Cu are annealed for 1 h at two different annealing temperatures, 400 and 800 C, and then processed by HPT at room temperature under a pressure of 6.0 GPa for 1/4, 1/2, 1, 5, and 10 turns. Samples are stored for 6 months after HPT processing to examine the self-annealing effects. Electron backscattered diffraction (EBSD) measurements are recorded for each disk at three positions: center, mid-radius, and near edge. Microhardness measurements are also recorded along the diameters of each disk. Both alloys show rapid hardening and then strain softening in the very early stages of straining due to self-annealing with a clear delay in the onset of softening in the alloy initially annealed at 800 C. This delay is due to the relatively larger initial grain size compared to the alloy initially annealed at 400 C. The final microstructures consist of homogeneous fine grains having average sizes of 0.28 and 0.34 mm for the alloys initially annealed at 400 and 800 C, respectively. A new model is proposed to describe the behavior of the hardness evolution by HPT in high purity OFHC Cu.

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Section: Introductionsupporting

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Effect of Initial Annealing Temperature on Microstructural Development and Microhardness in High‐Purity Copper Processed by High‐Pressure Torsion

et al. 2017

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“…1 where the lower dashed line denotes the hardness value of Hv ≈ 50 for the as-annealed sample prior to HPT. It should be noted that pure Al and Al alloys are typical materials showing reasonable hardness homogeneity through the height directions of the disks after HPT processing [15][16][17] and thus there is no influence of the measurement sections within the disk height on the hardness variations along the disk diameters.…”

Section: Vickers Microhardness Variationsmentioning

confidence: 99%

Significance of grain refinement on microstructure and mechanical properties of an Al-3% Mg alloy processed by high-pressure torsion

Lee

Han

Janakiraman

et al. 2016

Journal of Alloys and Compounds

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Significance of grain refinement on microstructure and mechanical properties of an Al-3% Mg alloy processed by high-pressure torsion, Journal of Alloys and Compounds (2016), doi: 10.1016/ j.jallcom.2016 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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“…This heterogeneity in hardness distribution is attributed to the heterogeneous microstructure caused by unusual plastic ow patterns during HPT. [38][39][40] Hardening occurs at the surface of the HPT processed specimen owing to martensitic transformations, accumulation of dislocation and grain re nement. This hardening may prevent strain from developing deeply below the specimen s surface, causing the heterogeneity in the microstructure.…”

Section: Effect Of Hpt and Subsequent Short Annealing On Hardness Dismentioning

confidence: 99%

Optimization of Microstructure and Mechanical Properties of Co–Cr–Mo Alloys by High-Pressure Torsion and Subsequent Short Annealing

et al. 2016

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The main target of this study is to optimize the microstructure and to achieve an optimization for the mechanical properties in a biomedical Co-Cr-Mo (CCM) alloy with the nominal composition of Co-28Cr-6Mo (mass%) subjected to high-pressure torsion (HPT) and subsequent short annealing. The γ → ε phase transformation and grain re nement occur in the CCM alloy subjected to HPT processing at an equivalent strain (ε eq ) of 2.25 (CCM HPT ). The HPT processing causes a decrease in the elongation due to the formation of an excessive amount of ε phase. For removal of the excessive amount of ε phases, the CCM HPT was subjected to a short annealing (CCM HPTA ). The effect of the short annealing temperature (1073 K, 1273 K, and 1473 K; annealing time was xed at 0.3 ks) on CCM HPT was investigated. In addition, the effect of the length of duration for the short annealing (0.06 ks, 0.3 ks, and 0.6 ks;) for a xed annealing temperature of 1273 K on CCM HPT was studied. CCM HPTA(1273 K) annealed for 0.3 ks shows a good optimization of mechanical properties that include high strength and large elongation owing to its ultra ne-grained microstructure, and removal of excessive ε phases.

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An investigation of hardness homogeneity throughout disks processed by high-pressure torsion

Cited by 184 publications

References 32 publications

Effect of Initial Annealing Temperature on Microstructural Development and Microhardness in High‐Purity Copper Processed by High‐Pressure Torsion

Effect of Initial Annealing Temperature on Microstructural Development and Microhardness in High‐Purity Copper Processed by High‐Pressure Torsion

Significance of grain refinement on microstructure and mechanical properties of an Al-3% Mg alloy processed by high-pressure torsion

Optimization of Microstructure and Mechanical Properties of Co–Cr–Mo Alloys by High-Pressure Torsion and Subsequent Short Annealing

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