Dynamic recrystallization of wet synthetic polycrystalline halite: dependence of grain size distribution on flow stress, temperature and strain

AbstractThe paper reports new experimental results describing properties and microstructure of nanocrystalline metals. Nano- and sub-micron aluminium has been produced by hydrostatic extrusion at ambient tempearture. The structures have been quantified in terms of size of grains and misorientation of the grain boundaries. Different average size of grains, variable normalized width of grain size distribution and changing grain boundary misorientation distribution functions have been revealed depending on processing parameters. The results of the tensile tests showed that the average grain size, grain size distribution and the distribution function of misorientation angles influence the flow stress of obtained nano-metals. In order to explain the observed difference in the properties of nano- and micro-sized aluminium alloys, a Finite Element Method models have been developed, which assumes that both grain boundaries and grain interiors may accommodated elastic and non-linear plastic deformation. These models assumed true geometry of grains (which differed in size and shape). Also, variable mechanical properties of grain boundaries have been taken into account (elastic modulus, yield strength and work hardening rate). The results of modelling explain in a semi-quantitative way macroscopic deformation of nano-crystalline aggregates. In particular, they illustrate the importance of the interplay between properties of grain boundaries and grain interiors in elastic and plastic regime.

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The Effect of Grain Size Distribution on the Mechanical Properties of Nanometals

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.140.185 ◽

2008 ◽

Vol 140 ◽

pp. 185-190 ◽

Cited By ~ 5

Author(s):

T.B. Tengen ◽

Tomasz Wejrzanowski ◽

R. Iwankiewicz ◽

Krzysztof Jan Kurzydlowski

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Flow Stress ◽

Size Distribution ◽

Grain Size Distribution ◽

Deformation Mechanisms ◽

Average Grain Size ◽

Significant Interest ◽

Size Dispersion ◽

The Relationship

Predicting the properties of a material from knowledge of the internal microstructures is attracting significant interest in the fields of materials design and engineering. The most commonly used expression, known as Hall-Petch Relationship (HPR), reports on the relationship between the flow stress and the average grain size. However, there is much evidence that other statistical information that the grain size distribution in materials may have significant impact on the mechanical properties. These could even be more pronounced in the case of grains of the nanometer size, where the HPR is no longer valid and the Reverse-HPR is more applicable. This paper proposes a statistical model for the relationship between flow stress and grain size distribution. The model considered different deformation mechanisms and was used to predict mechanical properties of aluminium and copper. The results obtained with the model shows that the dispersion of grain size distribution plays an important role in the design of desirable mechanical properties. In particular, it was found that that the dependence of a material’s mechanical properties on grain size dispersion also follows the HPR to Inverse-HPR type of behaviour. The results also show that copper is more sensitive to changes in grain size distribution than aluminium.

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The Issue of Grain Size Distribution Using Mean Field Models for Dynamic and Post-Dynamic Recrystallization

Materials Science Forum ◽

10.4028/www.scientific.net/msf.879.1794 ◽

2016 ◽

Vol 879 ◽

pp. 1794-1799 ◽

Cited By ~ 1

Author(s):

Guillaume Smagghe ◽

David Piot ◽

Frank Montheillet ◽

G. Perrin ◽

A. Montouchet ◽

...

Keyword(s):

Grain Size ◽

Dynamic Recrystallization ◽

Size Distribution ◽

Grain Size Distribution ◽

Mean Field ◽

304L Stainless Steel ◽

Mean Field Model ◽

Average Grain Size ◽

Fundamental Equations ◽

Good Agreement

A mean field model for discontinuous dynamic recrystallization (DDRX) has been developed and chained with a post-dynamic recrystallization (PDRX) model to predict transient and steady-state flow stresses and average grain sizes. Numerical results are compared with experimental data obtained on a 304L stainless steel yielding to a good agreement in terms of average grain size. However an unrealistic grain-size distribution is observed using DDRX, which affects results of the PDRX model. This result is discussed with respect to the fundamental equations of DDRX.

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