Special Issue "Dynamic Recrystallization Behavior of Metallic Materials"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: 31 August 2018

Special Issue Editors

Guest Editor
Prof. Roland E. Logé

Thermomechanical Metallurgy Laboratory–PX Group Chair, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland
Website | E-Mail
Interests: microstructure and texture evolutions in metals and alloys; recrystallization and grain growth; thermo-mechanical treatments; multiscale modelling; selective laser melting; laser shock peening
Guest Editor
Prof. Ke Huang

School of Mechancial Engineering, Xi'an Jiaotong University, Xi'an, China
E-Mail
Interests: recrystallization; crystallographic texture; precipitation, deformation structure; microstructure characterization; numerical modelling

Special Issue Information

Dear Colleagues,

This Special Issue of Metals deals with all aspects of the dynamic recrystallization of metals and alloys. The topic is not new, but still represents a very active research area, due to the complex multiscale nature of the problem, and its industrial importance.

A better understanding of dynamic recrystallization phenomena implies the use of predictive models at different scales, which describe the complex evolutions of interface patterns, looking at the local kinetic equations, and at the global meso- or macroscopic resulting properties. These models include the so-called mean field models taking advantage of differential equations operating on well-chosen state variables. They also refer to more demanding mesoscale computational models with explicit representations of microstructures through grids or meshes (Monte Carlo, Cellular Automata, Phase field, Level set, etc.). At the lowest scale, atomistic simulations provide new insights into the mechanisms operating during interface motion.

Experimental approaches also explore the dynamics of interfaces at different scales, looking at nucleation phenomena, texture changes, interaction between moving boundaries and dislocations structures, boundary mobility and energy, coupling with twinning, phase transformation and precipitation. In situ experiments at Large Facilities provide more and more information on those subjects, which need to be translated into appropriate mechanical and physical descriptions. At the laboratory scale, the possibility to explore dynamic recrystallization in macroscopic samples from the measurement of temperature, stress/strain, strain rate, geometry or resistivity changes, deserves further investigation, in particular by taking advantage of multiscale models, and studying variable thermal and mechanical conditions, which are of utmost importance in industry and have been so far relatively neglected in academic work.

Prof. Roland E. Logé
Prof. Ke Huang
Guest Editors

Manuscript Submission Information

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Keywords

  • dynamic recrystallization
  • dynamic recovery
  • nucleation
  • texture
  • precipitation
  • grain boundary migration
  • grain refinement
  • microstructure characterization
  • mechanical properties
  • multiscale modelling

Published Papers (3 papers)

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Research

Open AccessArticle Softening Characterization of 300M High-Strength Steel during Post-Dynamic Recrystallization
Metals 2018, 8(5), 340; https://doi.org/10.3390/met8050340
Received: 7 April 2018 / Revised: 7 May 2018 / Accepted: 8 May 2018 / Published: 10 May 2018
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Abstract
This paper investigates softening phenomena within the post-dynamic recrystallization (PDRX) process in 300M high-strength steel specimens with different initial dynamically recrystallized volume fractions. Isothermal, interrupted compression experiments were performed on a Gleeble-3500 at a temperature of 1273 K and strain rate of 0.01
[...] Read more.
This paper investigates softening phenomena within the post-dynamic recrystallization (PDRX) process in 300M high-strength steel specimens with different initial dynamically recrystallized volume fractions. Isothermal, interrupted compression experiments were performed on a Gleeble-3500 at a temperature of 1273 K and strain rate of 0.01 s−1. To acquire different initial volume fractions of dynamically recrystallized (DRX) grains, deformation was interrupted at two strain levels and immediately followed by isothermal annealing treatments. The softening behaviors respectively caused by the static recrystallization (SRX) and metadynamic recrystallization (MDRX) were qualitatively characterized by variations in the mechanical properties of the deformed and recrystallized grains. On the basis of the Taylor dislocation model, the evolution of geometric necessary dislocations (GNDs) and statistically stored dislocations (SSDs) densities were also discussed to qualitatively clarify the nature of different softening behaviors. Results indicate that the SRX occurred alone in samples without initial DRX grains, after an incubation time of approximately 50 s, while MDRX initially appeared within 1 s and completed at about 8 s in samples with a high initial volume fraction of DRX grains. The microhardness, indentation hardness, and Young’s modulus in the deformed and recrystallized grains decreased gradually with an increase of MDRX and SRX volume fractions. The sink-in and pile-up phenomena were enhanced by the SRX and MDRX softening processes, respectively. The SSDs density decreased more noticeably during the MDRX process than that during the SRX, which indicates that the MDRX process contributed to a more significant softening effect within the microstructural evolution regimes. Full article
(This article belongs to the Special Issue Dynamic Recrystallization Behavior of Metallic Materials)
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Open AccessArticle Mechanism of Dynamic Recrystallization and Evolution of Texture in the Hot Working Domains of the Processing Map for Mg-4Al-2Ba-2Ca Alloy
Metals 2017, 7(12), 539; https://doi.org/10.3390/met7120539
Received: 21 October 2017 / Revised: 14 November 2017 / Accepted: 22 November 2017 / Published: 2 December 2017
Cited by 2 | PDF Full-text (7114 KB) | HTML Full-text | XML Full-text
Abstract
The occurrence of dynamic recrystallization (DRX) and its effect on the evolution of texture during uniaxial compression of a creep-resistant cast Mg-4Al-2Ba-2Ca alloy in the temperature range of 260–500 °C and strain rate range of 0.0003–10 s−1 has been studied using transmission
[...] Read more.
The occurrence of dynamic recrystallization (DRX) and its effect on the evolution of texture during uniaxial compression of a creep-resistant cast Mg-4Al-2Ba-2Ca alloy in the temperature range of 260–500 °C and strain rate range of 0.0003–10 s−1 has been studied using transmission electron microscopy and electron backscatter diffraction techniques with a view to understand its mechanism. For this purpose, a processing map has been developed for this alloy, which revealed two domains of DRX in the temperature and strain rate ranges of: (1) 300–390 °C/0.0003–0.001 s−1 and (2) 400–500 °C/0.0003–0.5 s−1. In Domain 1, DRX occurs by basal slip and recovery by dislocation climb, as indicated by the presence of planar slip bands and high dislocation density leading to tilt boundary formation and a low-intensity basal texture. On the other hand, DRX in Domain 2 occurs by second order pyramidal slip and recovery by cross-slip since the microstructure revealed tangled dislocation structure with twist boundaries and randomized texture. The high volume content of intermetallic phases Mg21Al3Ba2 and (Al,Mg)2Ca eutectic phase is considered to be responsible for the observed hot deformation behavior. Full article
(This article belongs to the Special Issue Dynamic Recrystallization Behavior of Metallic Materials)
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Figure 1a

Open AccessFeature PaperArticle In Situ Characterization of Inconel 718 Post-Dynamic Recrystallization within a Scanning Electron Microscope
Metals 2017, 7(11), 476; https://doi.org/10.3390/met7110476
Received: 22 September 2017 / Revised: 29 October 2017 / Accepted: 2 November 2017 / Published: 4 November 2017
Cited by 1 | PDF Full-text (14350 KB) | HTML Full-text | XML Full-text
Abstract
Microstructure evolution within the post-dynamic regime following hot deformation was investigated in Inconel 718 samples with different dynamically recrystallized volume fractions and under conditions such that no δ-phase particles were present. In situ annealing treatments carried out to mimic post-dynamic conditions inside the
[...] Read more.
Microstructure evolution within the post-dynamic regime following hot deformation was investigated in Inconel 718 samples with different dynamically recrystallized volume fractions and under conditions such that no δ-phase particles were present. In situ annealing treatments carried out to mimic post-dynamic conditions inside the Scanning Electron Microscope (SEM) chamber suggest the occurrence of both metadynamic and static recrystallization mechanisms. Static recrystallization was observed in addition to metadynamic recrystallization, only when the initial dynamically recrystallized volume fraction was very small. The initial volume fraction of dynamically recrystallized grains appears to be decisive for subsequent microstructural evolution mechanisms and kinetics. In addition, the formation of annealing twins is observed along with the growth of recrystallized grains, but then the twin density decreases as the material enters the capillarity-driven grain growth regime. Full article
(This article belongs to the Special Issue Dynamic Recrystallization Behavior of Metallic Materials)
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Graphical abstract

Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Some facts we can learn from analytical modeling of DDRX in pure metals and solid solutions
Author: F. Montheillet
Affiliation: Mines Saint-Etienne, Univ Lyon, CNRS, UMR 5307 LGF, Centre SMS, F-42023 Saint-Etienne France
Abstract: Modeling and simulation of discontinuous dynamic recrystallization (DDRX) are now commonly carried out by numerical methods, such as finite element computation, phase field or vertex techniques, or cellular automata. Very precise results can be obtained at the microscopic level, regarding velocity fields, dislocation densities, nucleation sites, grain boundary migration, etc. It is, however, also possible to use simple analytical (or quasi-analytical) approaches on the "mesoscopic" or grain-scale level to get relevant information about the basic mechanisms involved in DDRX. Furthermore, insofar as the steady state behaviour is concerned, closed formed equations can be obtained, from which it is easy to assess the influence of the various parameters (temperature, strain rate, materials constants) on the DDRX flow stress and microstructure. This is illustrated in the present paper, starting from a "generic" model previously proposed by the author. The main assumptions and equations are first reminded and some examples are given for materials with power law strain hardening without dynamic recovery, or including the latter according to the Yoshie-Laasraoui-Jonas formulation. The basic equations are then extended to the case of solid solutions. Macroscopic strain rate sensitivities and apparent activation energies are derived from the results, as well as the classical relationship between average grain size and flow stress in the steady state (Derby equation). Finally, the analytical approach allows to derive not only average quantities but also, to some extent, distributions of the latter, as shown through the example of grain sizes. In summary, the paper aims to offer the view that even in our time analytical approaches are able to provide a deep understanding of physical phenomena like DDRX, and still have their place besides, and as far as possible interacting with, numerical simulations.
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