Overview no. 35 Dynamic recrystallization: Mechanical and microstructural considerations

Sakai, Taku; Jonas, John J.

doi:10.1016/0001-6160(84)90049-x

Cited by 995 publications

(534 citation statements)

References 33 publications

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“…5(c)) shows grain refinement of D rex /D 0 = 0.5 (D 0 is the initial mean grain size) up to 50% strain, which is consistent with the common empirical criterion (Sakai and Jonas, 1984) that a single stress peak DRX usually corresponds to 2D rex ≤ D 0 . The corresponding experiment data (Wusatowska-Sarnek et al, 2002) shows D rex /D 0 = 0.2, measured after a strain of ∼ 1.3 when the steady-state has been reached.…”

Section: Kinetics Of Drxsupporting

confidence: 79%

“…These can be considered as legitimate in modeling DRX, of which the onset is still at a relatively small strain level (usually ∼ 0.1) (Sakai and Jonas, 1984;Rollett et al, 2004). In addition, once DRX is initiated, the mechanical behavior starts to be dominated by the migration of DRX grain boundaries modeled by PF, and the error due to small-strain assumption is further relieved.…”

Section: Deformation Kinematicsmentioning

confidence: 99%

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An integrated full-field model of concurrent plastic deformation and microstructure evolution: Application to 3D simulation of dynamic recrystallization in polycrystalline copper

Zhao

Low

Wang

et al. 2016

International Journal of Plasticity

105

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Many time-dependent deformation processes at elevated temperatures produce significant concurrent microstructure changes that can alter the mechanical properties in a profound manner. Such microstructure evolution is usually absent in mesoscale deformation models and simulations. Here we present an integrated full-field modeling scheme that couples the mechanical response with the underlying microstructure evolution. As a first demonstration, we integrate a fast Fourier transform-based elasto-viscoplastic (FFT-EVP) model with a phase-field (PF) recrystallization model, and carry out three-dimensional simulations of dynamic recrystallization (DRX) in polycrystalline copper. A physics-based coupling between FFT-EVP and PF is achieved by (1) adopting a dislocation-based constitutive model in FFT-EVP, which allows the predicted dislocation density distribution to be converted to a stored energy distribution and passed to PF, and (2) implementing a stochastic nucleation model for DRX. Calibrated with the experimental DRX stress-strain curves, the integrated model is able to deliver full-field mechanical and microstructural information, from which quantitative description and analysis of DRX can be achieved. It is suggested that the initiation of DRX occurs significantly earlier than previous predictions, due to heterogeneous deformation. DRX grains are revealed to form at both grain boundaries and junctions (e.g., quadruple junctions) and tend to grow in a wedge-like fashion to maintain a triple line (not necessarily in equilibrium) with old grains. The resulting stress redistribution due to strain compatibility is found to have a profound influence on the subsequent dislocation evolution and softening.

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Section: Kinetics Of Drxsupporting

confidence: 79%

Section: Deformation Kinematicsmentioning

confidence: 99%

An integrated full-field model of concurrent plastic deformation and microstructure evolution: Application to 3D simulation of dynamic recrystallization in polycrystalline copper

Zhao

Low

Wang

et al. 2016

International Journal of Plasticity

105

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“…Such flow behaviors are generally similar to those of conventional dynamic recrystallization (DRX) behavior appearing in cubic metals. 7) At low temperatures below 523 K, in contrast, the -" curve shows rapid work hardening in low strain and a sharp stress peak at around " ¼ 0:2, and then work softening followed by steady state flow at high strains. The -" curve at 473 K exhibits a sharp and higher stress peak of above 300 MPa at around " ¼ 0:2, immediately followed by brittle fracture.…”

Section: Deformation Behaviorsmentioning

confidence: 99%

“…The dDRX involves the nucleation of new, dislocation free grains followed by subsequent long-distance growth through migration of high angle grain boundaries. 7) During hot deformation of Mg alloy, in contrast, kink bands are frequently evolved in original grain interiors at low strains. The number and misorientation angle of kink bands rapidly increase with further deformation, finally resulting in development of new fine-grained structures at strains above 0.5.…”

Section: Grain Refinement In Mg Alloy During Mdfmentioning

confidence: 99%

Mechanical Properties of Magnesium Alloy AZ31 after Severe Plastic Deformation

Xing

Miura

et al. 2008

Mater. Trans.

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Grain refinement of magnesium alloy AZ31 was studied in multidirectional forging (MDF) under decreasing temperature conditions. MDF was carried out up to large cumulative strains of 5.6 with changing the loading direction during decrease in temperature from pass to pass. MDF can accelerate the uniform development of very fine-grained structures and an increase of the plastic workability at low temperatures. New grain structures with the minimal grain size of 0.23 mm can be developed by continuous dynamic recrystallization at a final processing temperature of 403 K. As a result, the multidirectional-forged alloy showed excellent higher strength as well as moderate ductility at room temperature, and also a superplastic elongation of over 300% at 423 K. The mechanisms of strain-induced and fine-grained structure development and of the excellent plastic deformation are discussed in detail.

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“…Under strain gradients, additional hardening may occur due to the generation of geometrically necessary dislocations (GNDs) [43]. There can also be additional softening due to microstructural changes, namely dynamic recrystallization [44], which has not been widely considered in the modelling of particle impact. It should be noted that the thermal softening as considered in constitutive equations, as in Eq.…”

Section: Underlying Physics and Materials Modelsmentioning

confidence: 99%

Cold spraying – A materials perspective

et al. 2016

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Cold spraying is a solid-state powder deposition process with several unique characteristics, allowing production of coatings or bulk components from a wide range of materials. The process has attracted much attention from academia and industry over the past two decades.The technical interest in cold spraying is twofold: first as a coating process for applications in surface technology, and second as a solid-state additive manufacturing process, offering an alternative to selective laser melting or electron beam melting methods. Moreover, cold spraying can be used to study materials behaviour under extremely high strain rates, high pressures and high cooling rates. The cold spraying process is thus considered to be relevant for various industrial applications, as well as for fundamental studies in materials science.This article aims to provide an overview of the cold spray process, the current understanding of the deposition mechanisms, and the related models and experiments, from a materials science perspective. IntroductionCold spraying (CS) is a solid-state material deposition technique, where micron-sized particles of a powder bond to a substrate as a result of high-velocity impact and the associated severe plastic deformation. Acceleration of particles to high velocities is obtained via expansion of a pressurised and (ironically) 'hot' gas through a diverging-converging nozzle.Despite heating the process gas -which is to provide higher acceleration of the gas and also to facilitate particle deformation through thermal softening -the feedstock remains in the solid state throughout the entire process; hence the name 'cold' spraying. This is to underline the contrast to conventional thermal spraying where particles are completely or partially molten upon impact onto the substrate. Alternative terminology includes cold gas spray, micro cold spray, cold gas dynamic spray, kinetic spray, supersonic particle deposition and metal powder application (MPA), all of which refer to the same principle of solid-state powder deposition as described above. CS is used for coating and repair. It is also used for additive manufacturing (AM) at relatively high deposition rates as compared to the methods based on selective laser or electron beam melting. The main advantage of CS is that it alleviates the problems associated with high temperature processing of materials, such as oxidation and unfavourable structural changes. It is possibly the only continuous method to produce bulk components of metastable materials that are available only in the powder form, e.g. as obtained from mechanical attrition or gas atomisation. The aim of the present paper is to provide an overview of CS from a materials perspective, particularly for a broader audience in materials research, e.g. with interest in dynamic phenomena, plasticity and phase transformations. In terms of application and properties, CS is perhaps best to be compared to thermal spraying processes, as in [24,25]. In view of relevant physical phenomena, however, CS is mos...

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Overview no. 35 Dynamic recrystallization: Mechanical and microstructural considerations

Cited by 995 publications

References 33 publications

An integrated full-field model of concurrent plastic deformation and microstructure evolution: Application to 3D simulation of dynamic recrystallization in polycrystalline copper

An integrated full-field model of concurrent plastic deformation and microstructure evolution: Application to 3D simulation of dynamic recrystallization in polycrystalline copper

Mechanical Properties of Magnesium Alloy AZ31 after Severe Plastic Deformation

Cold spraying – A materials perspective

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