Temat: dynamic recrystallization

Skocz do pozycji: 1.

Tytuł:: Practical Approach to Determining Dynamic Recrystallization Parameters Using Finite Element Optimization of Backward Extrusion Process
Autorzy:: Irani, Missam
Joun, Mansoo
Tematy:: dynamic recrystallization
grain size
optimization
simulation; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/352583.pdf Link otwiera się w nowym oknie
Opis:: In this study, we present a new method for obtaining the parameters of the Johnson-Mehl-Avrami-Kolmogorov equation for dynamic recrystallization grain size. The method consists of finite-element analysis and optimization techniques. An optimization tool iteratively minimizes the error between experimental values and corresponding finite-element solutions. Isothermal backward extrusion of the AA6060 aluminum alloy was used to acquire the main parameters of the equation for predicting DRX grain size. We compared grain sizes predicted using optimized and reference parameters with experimental values from the literature and found better agreement when the optimized parameters were applied.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Analytical Descriptions of Dynamic Softening Mechanisms for Ti-13Nb-13Zr Biomedical Alloy in Single Phase and Two Phase Regions
Autorzy:: Quan, G.-Z.
Wang, X.
Li, Y.-L.
Zhang, L.
Tematy:: biomedical titanium alloy
flow stress
dynamic recovery
dynamic recrystallization
dynamic softening; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/353917.pdf Link otwiera się w nowym oknie
Opis:: Dynamic softening behaviors of a promising biomedical Ti-13Nb-13Zr alloy under hot deformation conditions across dual phase α + β and single phase β regions were quantitatively characterized by establishing corresponding dynamic recovery (DRV) and dynamic recrystallization (DRX) kinetic models. A series of wide range hot compression tests on a Gleeble-3500 thermo-mechanical physical simulator were implemented under the strain rate range of 0.01-10 s⁻¹ and the temperature range of 923-1173 K. The apparent differences of flow stress curves obtained in dual phase α + β and single phase β regions were analyzed in term of different dependence of flow stress to temperature and strain rate and different microstructural evolutions. Two typical softening mechanisms about DRV and DRX were identified through the variations of a series of stress-strain curves acquired from these compression tests. DRX is the dominant softening mechanism in dual phase α + β range, while DRV is the main softening mechanism in single phase β range. The DRV kinetic model for single phase β region and the DRX kinetic model for dual phase α + β region were established respectively. In addition, the microstructures of the compressed specimens were observed validating the softening mechanisms accordingly.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Study on Dynamic Recrystallization Models of 21-4N Heat Resistant Steel
Autorzy:: Li, Yiming
Huang, Xiaomin
Ji, Hongchao
Li, Yaogang
Wang, Baoyu
Tang, Xuefeng
Tematy:: 21-4N
hot deformation
dynamic recrystallization
critical strain
volume fraction; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/2049422.pdf Link otwiera się w nowym oknie
Opis:: The high-temperature deformation process and dynamic recrystallization (DRX) process of 21-4N were investigated under the conditions of the deformation temperature range of 1273~1453K, the strain rate range of 0.01~10s-1 and the deformation degree of 60% (the total deformation is 0.916) by using Gleeble-1500D thermal simulated test machine. The curves of stress-strain (σ – ε) were obtained, and the curves of work hardening rate (θ) and strain (ε) were obtained by taking derivative of σ – ε. The DRX critical strains under different conditions were determined by the curves of work hardening rate (θ – ε), and the DRX critical strain model was established. The peak strains of 21-4N were obtained by the curves of σ – ε, the relationship between peak stress (σp) and critical strain (εc) was determined, and the peak strain model was established. The DRX volume fraction models of 21-4N were established by using Avrami equation. The DRX grain size of 21-4N was calculated by Image Pro Plus 6.0, and its DRX grain size models were established.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Microstructure Evolution Mechanism of AISI 1045 Steel Under High Speed Deformation
Autorzy:: Luo, Lingen
Pang, Jianming
Song, Yaoxin
Liu, Shulan
Yin, Guoliang
Peng, Hao
Pu, Chunlei
Lin, Yinhe
Li, Jingwei
Shi, Xuefeng
Tematy:: high speed cutting
continue dynamic recrystallization
microstructure evolution
microstructure
AISI 1045 steel; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/59110841.pdf Link otwiera się w nowym oknie
Opis:: AISI 1045 steel has the characteristics of high strain rate, large strain, and sharp rise in temperature during high-speed deformation process, resulting in a concentrated deformation band and fine structure. In this work, the microstructure of submicron-sized grains in AISI 1045 steel material formed under 106 s-1 during a high speed cutting process was examined. To reveal the dynamic evolution mechanism of the AISI 1045 microstructure, the continuous dynamic recrystallization theory was introduced. The results show a high dislocation density which favor the formation of small angle grain boundaries during the high speed cutting process. Kinetics calculations that use continuous dynamic recrystallization mechanisms prove that the recrystallization size is constant when the strain rate increases from 103 s-1 to 106 s-1, and the transition time is reduced from 6×10-5 s to 4×10-8 s. The recrystallization grains were gradually formed during the deformation of the material, not generated after the deformation.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: The Critical Conditions and Kinetics Required for Dynamic Recrystallization in a High-Carbon Tool Steel
Autorzy:: Zhang, Yong-Ji
Wu, Guang-Lian
Wu, Shang-Wen
Tematy:: high-carbon steel
critical conditions
dynamic recrystallization
work-hardening
kinetics model; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/2049419.pdf Link otwiera się w nowym oknie
Opis:: A hot compression test was conducted on a Gleeble-3500 thermo-simulation machine to study the critical conditions and kinetics of dynamic recrystallization in a high-carbon tool steel. The critical conditions for the initiation of dynamic recrystallization were determined using the working-hardening theory. The quantitative relationship between the critical characteristics of dynamic recrystallization and the hot deformation parameters were elucidated based on two different methods: the apparent method and physically based method. It was found that the two methods both have high applicability for the investigated steel, but the physically-based method needs less parameters and makes it possible to study the effect of different factors. A dynamic recrystallization kinetics model was used to calculate the recrystallization volume fraction under different conditions. The calculation results matched well with the data obtained from the flow curves.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Charakterystyka stanu strukturalnego stali niskowęglowej poddanej odkształceniu w zakresie minimum oporu plastycznego
Microstructure characterization of the low carbon steel deformed in the range of deformation resistance minimum
Autorzy:: Barbacki, A.
Samolczyk, J.
Tematy:: stal niskowęglowa
opór plastyczny
rekrystalizacja dynamiczna
low-carbon steel
deformation resistance
dynamic recrystallization; Pokaż więcej
Wydawca:: Sieć Badawcza Łukasiewicz - Instytut Obróbki Plastycznej
Powiązania:: https://bibliotekanauki.pl/articles/211588.pdf Link otwiera się w nowym oknie
Opis:: Przeprowadzono badania stali niskowęglowej (żelazo Armco) poddanej odkształceniu na ciepło w zakresie minimum oporu plastycznego. Minimum to stwierdzono w zakresie 825-850°C, natomiast podwyższenie temperatury odkształcenia do 900°C, w której ferryt już praktycznie nie występuje i stal posiada strukturę austenityczną, zwiększa opór plastyczny. Minimum oporu plastycznego przypada na temperatury odkształcenia, przy których zachodzi niemal pełna rekrystalizacja dynamiczna, zaś ilość austenitu w temperaturze odkształcenia nie jest na tyle duża, by znacząco wpłynąć na naprężenie uplastyczniające. Badania wykazały, że odkształcenie w zakresie minimum oporu plastycznego łączy się z wyraźnym rozdrobnieniem ziaren spowodowanym dynamiczną rekrystalizacją.
The low carbon steel (Armco iron) warm-worked in the range of deformation resistance minimum has been investigated. The minimum was found in the temperature range of 825 - 850°C, however, rising the deformation temperature up to 900 °C when ferrite practically disappears, leads to deformation resistance increase. It has been shown that deformation in the range of deformation resistance results in grain refinement due to dynamic recrystallization. Deformation resistance minimum appears when the steel is deformed in the temperature range leading to practically complete dynamic recrystallization and there is not enough austenite to increase significantly the plastic stress.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Effect of Al-5Ti-1B Addition on Solidification Microstructure and Hot Deformation Behavior of DC-Cast Al-Zn-Mg-Cu Alloy
Autorzy:: Lee, Junho
Seo, Namhyuk
Lee, Sang-Hwa
Euh, Kwangjun
Kang, Singon
Son, Seung Bae
Lee, Seok-Jae
Jung, Jae-Gil
Tematy:: Al-Zn-Mg-Cu alloy
microstructure
twinned dendrite
hot deformation
dynamic recrystallization; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/59193949.pdf Link otwiera się w nowym oknie
Opis:: This study investigated the effect of adding Al-5Ti-1B grain refiner on the solidification microstructure and hot deformation behavior of direct-chill (DC) cast Al-Zn-Mg-Cu alloys. The grain refiner significantly decreased the grain size and modified the morphology. Fine-grained (FG) alloys with grain refiners exhibit coarse secondary phases with a reduced number density compared to coarse-grained (CG) alloys without grain refiners. Dynamic recrystallization (DRX) was enhanced at higher compression temperatures and lower strain rates in the CG and FG alloys. Both particle stimulated nucleation (PSN) and continuous dynamic recrystallization (CDRX) are enhanced in the FG alloys, resulting in decreased peak stress values (indicating DRX onset) at 450°C. The peak stress of the FG alloys was higher at 300-400°C than that of the CG alloys because of grain refinement hardening over softening by enhanced DRX.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Elaboration of Thermomechanical Treatment Conditions of Ti-V and Ti-Nb-V Microalloyed Forging Steels
Opracowanie warunków obróbki cieplno-plastycznej stali mikrostopowych do kucia typu Ti-V i Ti-Nb-V
Autorzy:: Opiela, M.
Tematy:: microalloyed steels
thermomechanical treatment
dynamic recrystallization
forgings
stale mikrostopowe
obróbka termomechaniczna
kinetyka rekrystalizacji
odkuwka; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/351214.pdf Link otwiera się w nowym oknie
Opis:: The goal of the work was to describe the forging conditions of thermomechanical treatment for Ti-V and Ti-Nb-V microalloyed steels. Conditions of hot-working allowing to obtain both the desired microstructure and mechanical properties of forgings were selected taking into consideration: precipitation analysis of MX-type (M – Nb, Ti, V; X – N, C) interstitial phases in austenite; research on the influence of the austenitizing temperature on the g-phase grain size; investigation of the continuous compression of specimens; and examination of the kinetics of recrystallization of plastically deformed austenite. The precipitation analysis of MX-type interstitial phases in austenite was conducted on the basis of a simplified thermodynamic model for equilibrium conditions as proposed by Adrian, assuming that individual MX phases are soluble in austenite. The effect of the austenitizing temperature in a range from 900 to 1200°C on the prior austenite grain size was investigated to verify the precipitation analysis of MX-type phases. The work also presents the results of the effect of Nb, Ti and V microadditions on flow stress, recrystallization kinetics and microstructure. Plastometric tests were carried out using the Gleeble 3800 thermomechanical test simulator. The studies provide the basis for a proper design of the manufacturing process for thermomechanical treatment of forged machine parts obtained from high-strength microalloyed steels.
Celem pracy było opracowanie warunków kucia metodą obróbki cieplno-plastycznej stali mikrostopowych typu Ti-V i Ti-Nb-V. Warunkiobróbki plastycznej na gorąco, zapewniające pożądaną mikrostrukturę i własności mechaniczne odkuwek, dobrano z uwzględnieniem: analizy wydzielania się w austenicie faz międzywęzłowych typu MX (M – Nb, Ti, V; X – N, C), badań wpływu temperatury austenityzowania na wielkość ziarn fazy g, badań ciągłego ściskania próbek oraz badań kinetyki rekrystalizacji austenitu odkształconego plastycznie. Analizę wydzielania faz międzywęzłowych typu MX w austenicie przeprowadzono na podstawie modelu zaproponowanego przez Adriana, zakładającego rozpuszczalność w warunkach równowagi termodynamicznej, indywidualnych faz MX w austenicie. Badania wpływu temperatury austenityzowania w zakresie od 900 do 1200°C na wielkość ziarn austenitu pierwotnego przeprowadzono w celu weryfikacji analizy wydzielania faz typu MX. Wpracyprzedstawiono także wyniki badań wpływu mikrododatków Nb, Ti i V na krzywe płynięcia, kinetykę rekrystalizacji i mikrostrukturę. Badania plastometryczne przeprowadzono przy użyciu symulatora termomechanicznego Gleeble 3800. Przeprowadzone badania stanowią podstawę prawidłowego projektowania procesu technologicznego obróbki cieplno-plastycznej kutych elementów maszyn o wysokiej wytrzymałości ze stali mikrostopowych.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Effects of V-Ti on Dynamic Recrystallization Behavior and Hot Deformation Activation Energy of 30MSV6 Micro-alloyed Steel
Autorzy:: Tavaei, K.
Meysami, A.
Tematy:: dynamic recrystallization
activation energy
hot compression
30MSV6 micro-alloyed steel
flow stress; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/353695.pdf Link otwiera się w nowym oknie
Opis:: In the current study, the hot deformation of medium carbon V-Ti micro-alloyed steel was surveyed in the temperature range of 950 to 1150°C and strain rate range of 0.001 to 1 s^-1 after preheating up to 1200°C with a compression test. In all cases of hot deformation, dynamic recrystallization took place. The influence of strain rate and deformation temperature on flow stress was analyzed. An increase in the strain rate and decrease in the deformation temperature postponed the dynamic recrystallization and increased the flow stress. The material constants of micro-alloyed steel were calculated based on the constitutive equations and Zener-Hollomon parameters. The activation energy of hot deformation was determined to be 458.75 kJ/mol, which is higher than austenite lattice self-diffusion activation energy. To study the influence of precipitation on dynamic recrystallization, the stress relaxation test was carried out in a temperature range of 950 to 1150°C after preheating up to 1200°C. The results showed no a stress drop while representing the interaction of particles with dynamic recrystallization.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Y Addition Effects on Hot Deformation Behavior of Cu-Zr Alloys with High Zr Content
Autorzy:: Tian, K.
Tian, B.
Volinsky, A. A.
Zhang, Y.
Liu, Y.
Du, Y.
Tematy:: Cu-1%Zr alloy
high Zr content
yttrium
hot deformation activation energy
dynamic recrystallization; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/350979.pdf Link otwiera się w nowym oknie
Opis:: Isothermal hot compression experiments were carried out using the Gleeble-1500D thermal mechanical simulator. The flow stress of the Cu-1%Zr and Cu-1%Zr-0.15%Y alloys was studied at hot deformation temperature of 550°C, 650°C, 750°C, 850°C, 900°C and the strain rate of 0.001 s^-1, 0.01 s^-1, 0.1 s^-1, 1 s^-1, 10 s^-1. Hot deformation activation energy and constitutive equations for two kinds of alloys with and without yttrium addition were obtained by correlating the flow stress, strain rate and deformation temperature. The reasons for the change of hot deformation activation energy of the two alloys were analyzed. Dynamic recrystallization microstructure evolution for the two kinds of alloys during hot compression deformation was analyzed by optical and transmission electron microscopy. Cu-1%Zr and Cu-1%Zr-0.15%Y alloys exhibit similar behavior of hot compression deformation. Typical dynamic recovery occurs during the 550-750°C deformation temperature, while dynamic recrystallization (DRX) occurs during the 850-900°C deformation temperature. High Zr content and the addition of Y significantly improved Cu-1%Zr alloy hot deformation activation energy. Compared with hot deformation activation energy of pure copper, hot deformation activation energy of the Cu-1%Zr and Cu-1%Zr-0.15%Y alloys is increased by 54% and 81%, respectively. Compared with hot deformation activation energy of the Cu-1%Zr alloy, it increased by 18% with the addition of Y. The addition of yttrium refines grain, advances the dynamic recrystallization critical strain point and improves dynamic recrystallization.
Dostawca treści:: Biblioteka Nauki

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