A critical review of experimental results and constitutive descriptions for metals and alloys in hot working
TL;DR: In this paper, a critical review on some experimental results and constitutive descriptions for metals and alloys in hot working, which were reported in international publications in recent years, is presented.
About: This article is published in Materials & Design.The article was published on 2011-04-01. It has received 1071 citations till now. The article focuses on the topics: Hot working & Constitutive equation.
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TL;DR: The dynamic recrystallization (DRX) phenomena occurring in different thermo-mechanical processing (TMP) conditions for various metallic materials are reviewed in this article.
1,177 citations
TL;DR: In this article, the authors investigated the evolution of hot deformed microstructures of a typical nickel-based superalloy by isothermal compression tests under the deformation temperature range of 920-1040°C and strain rate range of 0.001-1 s−1.
426 citations
TL;DR: In this paper, the volume fractions of DRX were estimated based on the conventional DRX kinetics model and a segmented model was proposed to describe the dynamic recrystallization behavior of a typical nickel-based superalloy.
391 citations
TL;DR: In this paper, the authors derived the flow stress of a 17-4 PH stainless steel during hot compression testing using the classical hyperbolic sine equation and the self-diffusion activation energy.
237 citations
03 Jan 2014-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the authors investigated the hot compressive deformation behaviors of a typical Ni-based superalloy over wide ranges of forming temperature and strain rate and developed processing maps to optimize the hot working processing.
Abstract: The hot compressive deformation behaviors of a typical Ni-based superalloy are investigated over wide ranges of forming temperature and strain rate. Based on the experimental data, the efficiencies of power dissipation and instability parameters are evaluated and processing maps are developed to optimize the hot working processing. The microstructures of the studied Ni-based superalloy are analyzed to correlate with the processing maps. It can be found that the flow stress is sensitive to the forming temperature and strain rate. With the increase of forming temperature or the decrease of strain rate, the flow stress significantly decreases. The changes of instability domains may be related to the adiabatic shear bands and the evolution of δ phase(Ni 3 Nb) during the hot formation. Three optimum hot deformation domains for different forming processes (ingot cogging, conventional die forging and isothermal die forging) are identified, which are validated by the microstructural features and adiabatic shear bands. The optimum window for the ingot cogging processing is identified as the temperature range of 1010–1040 °C and strain rate range of 0.1–1 s −1 . The temperature range of 980–1040 °C and strain rate range of 0.01–0.1 s −1 can be selected for the conventional die forging. Additionally, the optimum hot working domain for the isothermal die forging is 1010–1040 °C and near/below 0.001 s −1 .
221 citations
References
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01 Jan 1983
3,793 citations
TL;DR: The first crystallographic analysis of a non-γ-tubulin γTuRC component has resulted in a new appreciation of the relationships among all γ TuRC proteins, leading to a refined model of their organization and function.
Abstract: Microtubule nucleation is regulated by the γ-tubulin ring complex (γTuRC) and related γ-tubulin complexes, providing spatial and temporal control over the initiation of microtubule growth. Recent structural work has shed light on the mechanism of γTuRC-based microtubule nucleation, confirming the long-standing hypothesis that the γTuRC functions as a microtubule template. The first crystallographic analysis of a non-γ-tubulin γTuRC component (γ-tubulin complex protein 4 (GCP4)) has resulted in a new appreciation of the relationships among all γTuRC proteins, leading to a refined model of their organization and function. The structures have also suggested an unexpected mechanism for regulating γTuRC activity via conformational modulation of the complex component GCP3. New experiments on γTuRC localization extend these insights, suggesting a direct link between its attachment at specific cellular sites and its activation.
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TL;DR: In this paper, an experiment was designed to check the equivalence of the effects of changes in strain rate and in temperature on the stress-strain relation in metal deformation.
Abstract: An experiment has been designed to check a previously proposed equivalence of the effects of changes in strain rate and in temperature upon the stress‐strain relation in metals. It is found that this equivalence is valid for the typical steels investigated. The behavior of these steels at very high rates of deformation may, therefore, be obtained by tests at moderate rates of deformation performed at low temperatures. The results of such tests are described. Aside from changing the isothermal stress‐strain relation, an increase of strain rate tends to change the conditions from isothermal to adiabatic. It is found that at low temperatures, the adiabatic stress‐strain relation in the plastic range is radically different from the isothermal, having an initial negative rather than a positive slope. This initial negative slope renders unstable homogeneous plastic deformation.
2,263 citations
TL;DR: In this paper, a phenomenological model is proposed to incorporate the rate of dynamic recovery into the flow kinetics, which has been successful in matching many experimental data quantitatively, and it has been shown that the proportionality between the flow stress and the square root of the dislocation density holds, to a good approximation, over the entire regime; mild deviations arc primarily attributed to differences between the various experimental techniques used.
2,010 citations
TL;DR: An improved description of copper and ironcylinder impact (Taylor) test results has been obtained through the use of dislocation-mechanics-based constitutive relations in the Lagrangian material dynamics computer program EPIC•2.
Abstract: An improved description of copper‐ and iron‐cylinder impact (Taylor) test results has been obtained through the use of dislocation‐mechanics‐based constitutive relations in the Lagrangian material dynamics computer program EPIC‐2. The effects of strain hardening, strain‐rate hardening, and thermal softening based on thermal activation analysis have been incorporated into a reasonably accurate constitutive relation for copper. The relation has a relatively simple expression and should be applicable to a wide range of fcc materials. The effect of grain size is included. A relation for iron is also presented. It also has a simple expression and is applicable to other bcc materials but is presently incomplete, since the important effect of deformation twinning in bcc materials is not included. A possible method of acounting for twinning is discussed and will be reported on more fully in future work. A main point made here is that each material structure type (fcc, bcc, hcp) will have its own constitutive beha...
1,718 citations