Modeling of continuous dynamic recrystallization of Al-Zn-Cu-Mg alloy during hot deformation based on the internal-state-variable (ISV) method

Sun, Zhichao; Wu, Hongxing; Cao, Jing; Yin, Zhikun

doi:10.1016/j.ijplas.2018.03.002

Cited by 138 publications

(57 citation statements)

References 63 publications

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“…In the studied alloy, Figure 10 shows the energy dispersive spectrometer (EDS) results of the particles, suggesting the particles contain more Mg, Zn and a small amount of Cu due to the different diffusive ability, with a composition approaching the stoichiometric Mg(Zn, Cu) 2 phase. This finding is consistent with previous research [20,[48][49][50]. These small precipitates induce a strong pinning effect on dislocations and then retard the movement of dislocations, leading to a great flow stress hardening at the initial stage of hot compression.…”

Section: Microstructural Evolutionsupporting

confidence: 93%

Hot Deformation Behavior Considering Strain Effects and Recrystallization Mechanism of an Al-Zn-Mg-Cu Alloy

et al. 2020

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The hot deformation behavior of an Al-Zn-Mg-Cu alloy was investigated by hot compression test at deformation temperatures varying from 320 to 440 °C with strain rates ranging from 0.01 to 10 s−1. The results show that the Mg(Zn, Cu)2 particles as a result of the sufficient static precipitation prior to hot compression have an influence on flow softening. A constitutive model compensated with strain was developed from the experimental results, and it proved to be accurate for predicting the hot deformation behavior. Processing maps at various strains were established. The microstructural evolution demonstrates that the dominant dynamic softening mechanism stems from dynamic recovery (DRV) and partial dynamic recrystallization (DRX). The recrystallization mechanism is continuous dynamic recrystallization (CDRX). The microstructure observations are in good agreement with the results of processing maps. On account of the processing map and microstructural observation, the optimal hot processing parameters at a strain of 0.6 are at deformation temperature range of 390–440 °C and strain rate range of 0.010–0.316 s−1 with a peak efficiency of 0.390.

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Section: Microstructural Evolutionsupporting

confidence: 93%

Hot Deformation Behavior Considering Strain Effects and Recrystallization Mechanism of an Al-Zn-Mg-Cu Alloy

et al. 2020

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“…With deformation progressing, the LAGBs were rapidly transformed to HAGBs by rotation, which indicated that new recrystallized grains were formed from deformed grains. Generation of new recrystallized grains by rotation of grains without forming the nuclei was considered as the characteristic of continuous dynamic recrystallization; similar results can be found in previous works [39][40][41][42][43].…”

Section: Mechanism Of Microstructure Evolution During Spray Depositiosupporting

confidence: 75%

Hot Extrusion Enhanced Homogenization of Microstructure in a Spray Deposition Aluminum Alloy

Sheng

Yang

et al. 2020

Metals

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Homogeneous heat treatment serves the significant roles in eliminating the segregation and tuning the microstructure of alloy ingot. It usually cost tremendous power and time to achieve a homogeneous microstructure for aluminum alloys. In this article, the hot extrusion was directly introduced on the spray deposited aluminum alloy 7055 ingot before performing heat treatment to explore the newly feasible homogeneous routine. Equiaxed grains without dendrites or PPB were obtained in our current parameters of spray deposition, which allowed the as-deposited alloy to be deformed without being subjected to pre-homogeneous heat treatment. Significant amount of stored energy was produced during hot extrusion at 420 • C with area reduction ratio of 6.25, which effectively promoted the homogeneity of microstructure and reduced significantly the heat treatment time. A newly feasible short routine, heat treatment at 450 • C /6 h + 470 • C/1 h following the hot extrusion, proved capable of obtaining a homogeneous microstructure for the spray deposited aluminum alloy 7055. macro segregation could be improved by long-time homogenization heat treatment after casting, but it took tremendous power and time to achieve a uniform distribution of elements. It was well accepted that the diffusion of atoms would be accelerated under the combined effects of heat and stress [5]. However, the cast billet cannot be directly deformed due to the existence of macro segregation and casting defects, i.e., voids, concentration of elements, which would lead to the occurrence of cracks if not controlled properly. Thus, the as-cast aluminum alloy 7055 was usually subjected to homogeneous heat treatment at 46-47 • C for 24 h before deformation [6].Fortunately, spray deposition, a rapid solidification process, was proposed in the 1960s and was firstly applied in fabrication of super-high strength aluminum alloy in the 1990s [7,8]. With the assistance of spray deposition method, the aluminum alloy with high alloying could be produced with segregation being controlled at the micro-scale level. In this situation, the as-deposited alloy could be deformed under controllable parameters without being subjected to pre-homogenization heat treatment [9]. Recently, significant efforts have been made to study the hot deformation behaviors [10][11][12][13][14][15], quenching sensitivity [16][17][18][19], corrosion resistance [20-23] and weldability [24-29] of 7055. However, few reports were concerned with the improvement of homogenization in microstructure with less energy or short processes. In this article, hot extrusion was introduced to directly extrude the billet after spray deposition, wherein the microstructure evolution and corresponding mechanism during hot deformation and extrusion were uncovered. The subsequent heat treatment was employed to evaluate the effects of parameters on microstructure evolution of the hot-extruded alloy. Significant amount of stored energy was produced during hot extrusion at 420 • C with the area reduction ratio of 6.25, whic...

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“…Recrystallization models were constructed based on the hot compression tests with wide temperature and strain rate ranges to predict DRX evolution [5][6][7][8]. For a more accurate dynamic recrystallization model, it was of great importance to obtain the critical conditions for DRX, which was usually identified by using the θ − σ and (dθ/dσ) − σ curves [9][10][11]. Wu and Han [12] presented a kinetics model, and a third-order polynomial expression was fitted to determine the critical condition for the onset of dynamic recrystallization.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Dynamic Recrystallization in 5CrNiMoV Steel during Hot Forming

Wang

2020

Advances in Materials Science and Engineering

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The dynamic recrystallization (DRX) behavior of 5CrNiMoV steel was investigated through hot compression at temperatures of 830–1230°C and strain rates of 0.001–10 s−1. From the experimental results, most true stress-strain curves showed the typical nature of DRX that a single peak was reached at low strains followed by a decrease of stress and a steady state finally at relatively high strains. The constitutive behavior of 5CrNiMoV steel was analyzed to deduce the operative deformation mechanisms, and the correlation between flow stress, temperature, and strain rate was expressed as a sine hyperbolic type constitutive equation. Based on the study of characteristic stresses and strains on the true stress-strain curves, a DRX kinetics model was constructed to characterize the influence of true strain, temperature, and strain rate on DRX evolution, which revealed that higher temperatures and lower strain rates had a favorable influence on improving the DRX volume fraction at the same true strain. Microstructure observations indicated that DRX was the main mechanism and austenite grains could be greatly refined by reducing the temperature of hot deformation or increasing the strain rate when complete recrystallization occurred. Furthermore, a DRX grain size model of 5CrNiMoV was obtained to predict the average DRX grain size during hot forming.

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Modeling of continuous dynamic recrystallization of Al-Zn-Cu-Mg alloy during hot deformation based on the internal-state-variable (ISV) method

Cited by 138 publications

References 63 publications

Hot Deformation Behavior Considering Strain Effects and Recrystallization Mechanism of an Al-Zn-Mg-Cu Alloy

Hot Deformation Behavior Considering Strain Effects and Recrystallization Mechanism of an Al-Zn-Mg-Cu Alloy

Hot Extrusion Enhanced Homogenization of Microstructure in a Spray Deposition Aluminum Alloy

Evolution of Dynamic Recrystallization in 5CrNiMoV Steel during Hot Forming

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