Grain size distribution effects in superplasticity

Ghosh, A.; Raj, Rishi

doi:10.1016/0001-6160(81)90142-5

Cited by 111 publications

(29 citation statements)

References 16 publications

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“…Simultaneously, there is an increasing grain size effect. Most of these findings were congruently explained in [16] considering two contributions to creep, one from crystallographic slip and the other of GBS, by the use of the Ghosh and Raj model modification [117], which accounts for the grain size distribution.…”

Section: High Temperature Deformationsupporting

confidence: 67%

Influence of thermomechanical processing on the grain size, texture and mechanical properties of Mg-Al alloys

Srinivasarao¹,

Valle²,

Ruano³

et al. 2012

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The work carried out by the authors over the last decade on the processing, microstructural characterization and the mechanical behaviour of Mg alloys is reviewed. In particular, the potential for grain refinement and for the development of specific textures of large strain hot rolling (LSHR), equal channel angular pressing (ECAP) and accumulative roll bonding (ARB) is discussed. The recrystallization and the deformation mechanisms predominant in Mg alloys are analysed as a function of the grain size and the texture in a wide range of stresses, strain rates and temperatures. Finally, the feasibility of superplastic forming of Mg alloys was examined, taking into account the influence of factors such as grain size stability and microstructural heterogeneities.K e y w o r d s : magnesium alloys,

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Section: High Temperature Deformationsupporting

confidence: 67%

Influence of thermomechanical processing on the grain size, texture and mechanical properties of Mg-Al alloys

Srinivasarao¹,

Valle²,

Ruano³

et al. 2012

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“…In these cases the distribution of grain sizes (Ghosh and Raj, 1985) will influence the extent of slip locally; although there is no known evidence of changes in texture specific to these circumstances.…”

Section: Discussionmentioning

confidence: 99%

Texture Changes in an Al–LiAlloy Sheet SuperplasticallyDeformed to High Strains

Bowen¹

1987

Texture, Stress, and Microstructure

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Dedicated to the memory of Professor Giinter WassermannChanges in the texture and grain shape of an AI-Li alloy sheet superplastically deformed into the shape of a cone have been measured as a function of strain. The starting microstructure was characterised by strong {110}(112) and {123} (634) orientations, together with a number of minor orientations, and an elongated grain shape. Increases and decreases in the intensities of the individual orientations occurred at low values of strain (<0.5) as the elongated grains became equiaxed.Once all the grains were equiaxed, however, there was a continuous decrease in the intensities of all orientations, except for those of some minor orientations which remained essentially constant. The results are explained in terms of slip occurring in the early stages of deformation, because elongated grains will experience difficulty in sliding and rotating, but becoming negligible when grains are equiaxed and are free to slide and rotate. There was some evidence of dynamic recrystallisation but only whilst slip occurred.

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“…The initial work on this topic, in collaboration with Ghosh, [1,2] considered first a bimodal [1] and then a multimodal [2] distribution of the grain size to explain the change in the strain-rate sensitivity index m with the strain rate in the superplastic deformation of aluminum and titanium alloys. [2] The strain-rate dependence of m could be explained by well-spaced transitions of the different grain size domains, from diffusional to powerlaw creep, as the strain rate is increased.…”

Section: Introductionmentioning

confidence: 99%

“…[2] The strain-rate dependence of m could be explained by well-spaced transitions of the different grain size domains, from diffusional to powerlaw creep, as the strain rate is increased. The overall envelope of these transitions could explain the shape of the m curve.…”

Section: Introductionmentioning

confidence: 99%

“…These articles [1][2][3][4] highlight how stochastic modeling can lead to new results and predictions that cannot be obtained by models that are built on monolithic parameters. Another example of this algorithm was to show that the variability in the strength of a fiber bundle would be much less than the variability in the fracture strength of individual fibers.…”

Section: Introductionmentioning

confidence: 99%

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Inverse Problems in Stochastic Modeling of Mixed-Mode Power-Law and Diffusional Creep for Distributed Grain Size

Bai

Raj

2009

Metall Mater Trans A

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We seek to develop analytical methods through which the high-temperature deformation behavior of polycrystals can be explained in terms of the statistical distribution of the grain size. Changes in the stress exponent and grain size exponent with the strain rate are related to mixedmode deformation in which the large grains deform by power-law creep and the small grains by diffusional creep. Two results are obtained. The first is an expression (Eq.[13]) that relates the experimental values of the power-law exponent and the grain size exponent to the values predicted from the classical models for uniform grain size. This equation is independent of the standard deviation of the grain size distribution, the average grain size, and the temperature. In a second result, it is shown that measurements of the change in the stress exponent with the strain rate can be analyzed to estimate the standard deviation and the median value of the grain size. The possible significance of these results is tested against experiments on the superplastic deformation of aluminum, drawn from the literature.

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Grain size distribution effects in superplasticity

Cited by 111 publications

References 16 publications

Influence of thermomechanical processing on the grain size, texture and mechanical properties of Mg-Al alloys

Influence of thermomechanical processing on the grain size, texture and mechanical properties of Mg-Al alloys

Texture Changes in an Al–LiAlloy Sheet SuperplasticallyDeformed to High Strains

Inverse Problems in Stochastic Modeling of Mixed-Mode Power-Law and Diffusional Creep for Distributed Grain Size

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