Dynamic Recrystallization of Zircaloy-4 during Working within the Upper α-Range

2004 ◽  
Vol 467-470 ◽  
pp. 1151-1156 ◽  
Author(s):  
Cédric Chauvy ◽  
Pierre Barbéris ◽  
Frank Montheillet
Keyword(s):  
Dynamic Recrystallization ◽  
Large Strain ◽  
Large Angle ◽  
Rate Sensitivity ◽  
Large Strains ◽  
Strain Rates ◽  
Compression Tests ◽  
Continuous Dynamic Recrystallization ◽  
Ebsd Technique ◽  
Continuous Dynamic

Compression tests were used to simulate simple deformation paths within the upper a-range of Zircaloy-4 (i.e. 500°C-750°C). The mechanical behaviour reveals two different domains : at low temperatures and large strain rates, strain hardening takes place before flow softening, whereas this first stage disappears at lower flow stress levels. Strain rate sensitivity and activation energy were determined for both domains. Dynamic recrystallization was investigated using the Electron BackScattering Diffraction (EBSD) technique. It appears that the mechanism involved here is continuous dynamic recrystallization (CDRX), based on the increasing misorientation of subgrain boundaries and their progressive transformation into large angle boundaries. At low strains (e £ 0.3), CDRX kinetics are similar whatever the deformation conditions, while higher temperatures and lower strain rates promote recrystallization at large strains.

scholarly journals Investigation into Microstructure Evolution of Co–Ni–Cr–W–Based Superalloy During Hot Deformation

2021 ◽  
Vol 8 ◽  
Author(s):  
Wei Zhang ◽  
Baohong Zhu ◽  
Shuaishuai Wu ◽  
Shutian Tao
Keyword(s):  
Dynamic Recrystallization ◽  
Microstructure Evolution ◽  
Hot Deformation ◽  
Electron Backscatter Diffraction ◽  
Strain Rates ◽  
Compression Tests ◽  
Continuous Dynamic Recrystallization ◽  
Nucleation Mechanisms ◽  
Ebsd Technique ◽  
Continuous Dynamic

Hot compression tests were conducted using a Gleeble 3500 thermomechanical simulator at temperatures ranging from 1,000 to 1,200°C with the strain rate ranging from 0.1 to 10 s−1. Electron backscatter diffraction (EBSD) technique was employed by investigating the microstructure evolution during hot deformation. Microstructure observations reveal that deformation temperatures and strain rates have a significant effect on the DRX process. It is found that the fraction and grain size of DRX increase with the decreasing deformation temperature, along with the increasing high-angle grain boundaries (HAGBs). The fraction of DRX first decreases and then increases with the increase of strain rates. It is noted that there are both the nucleation mechanisms of discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) during the DRX process for Co–Ni–Cr–W–based superalloys. DDRX and CDRX are the primary and subsidiary nucleation mechanisms of DRX, respectively. It is also found that deformation temperatures and strain rates have almost no effect on the primary and subsidiary nucleation mechanisms of DRX. At the temperature above 1,150°C, the complete DRX occurred with the average grain sizes of about 25.32–29.01 μm. The homogeneity and refinement of microstructure can be obtained by selecting the suitable hot deformation parameters.

scholarly journals Flow modelling of Ti6Al4V under large strains

2020 ◽  
Vol 321 ◽  
pp. 12028
Author(s):  
HOGREFE Katharina ◽  
BUZOLIN Ricardo ◽  
POLETTI María Cecilia
Keyword(s):  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Grain Boundaries ◽  
Large Strain ◽  
Microstructural Characterization ◽  
Internal Variables ◽  
Large Strains ◽  
Continuous Dynamic Recrystallization ◽  
Flow Modelling ◽  
Continuous Dynamic

This work uses flow stresses obtained experimentally at different strain rates and temperatures to validate flow modelling results. Flow curves of Ti6Al4V are measured via torsion experiments with a Gleeble® 3800 up to effective strains of 8. A physically based model that describes the evolutions of microstructure and the flow stress in the β-phase field was developed. A model of continuous dynamic recrystallization (CDRX) based on the work of Gourdet and Montheillet [1] for aluminium alloys is combined in this work with elements taken from Kocks and Mecking [2]. The model consists of a detailed description of the microstructure, based on different dislocation density populations and grain boundaries. All these internal variables evolve according to a production and a recovery term correlated mathematically with the temperature and the strain rate. The modelled output variables besides the flow stress are the total, the interior and the wall dislocation densities as well as the subgrain and grain sizes developed by continuous dynamic recrystallization. The model describes the softening occurring during large strain deformations, which is partly produced by the formation of new high angle grain boundaries (HAGB). The fraction of HAGB was used to determine the recrystallization grade, validated with microstructural characterization.

Dynamic Recrystallization Mechanisms of Nickel Niobium Alloys during Hot Working

2021 ◽  
Vol 1016 ◽  
pp. 869-874
Author(s):  
Nadjoua Matougui ◽  
Mohamed Lamine Fares ◽  
David Piot
Keyword(s):  
Dynamic Recrystallization ◽  
Torsion Test ◽  
Large Strains ◽  
Strain Rates ◽  
Niobium Alloys ◽  
Continuous Dynamic Recrystallization ◽  
Hot Torsion ◽  
Hot Torsion Test ◽  
Continuous Dynamic ◽  
Electron Back Scattered Diffraction

This present work examines the influence of niobium in solid solution on the microstructural evolution of pure nickel at various deformation conditions. On this purpose, high-purity nickel and six model nickel-niobium alloys (Ni–0.01, 0.1, 1, 2, 5 and 10 wt. % Nb) were subjected to hot torsion test to large strains within the temperature range from 800 to 1000 °C at strain rates of 0.03, 0.1 and 0.3 s–1. Microstructural analyses were carried out using both optical and scanning electron microscopy-based electron back-scattered diffraction technique. The overall results showed the key role played by the Nb amount when coupled with various DRX mechanisms involved, i.e. DDRX, CDRX, and GDRX with respect to the prescribed deformation conditions, in reducing grain size and retarding DRX kinetics from which the microstructures of the examined materials such as Ni 2 and 10 wt. % Nb were seen evolving in different ways. In all these deformed materials, a transition from discontinuous dynamic recrystallization to continuous dynamic recrystallization was observed at low temperature and high strain rate whereas only discontinuous dynamic recrystallization occurred at high temperature.

Deformation Behavior and Dynamic Recrystallization of Hot Deformed GH625 Superalloy

2010 ◽  
Vol 146-147 ◽  
pp. 798-804
Author(s):  
Qing Miao Guo ◽  
De Fu Li ◽  
Sheng Li Guo
Keyword(s):  
Dynamic Recrystallization ◽  
Deformation Temperature ◽  
Volume Fraction ◽  
Optical Microscope ◽  
Strain Rates ◽  
Compression Tests ◽  
Continuous Dynamic Recrystallization ◽  
Transmission Electron ◽  
Lower Strain ◽  
Continuous Dynamic

Microstructure evolution during dynamic recrystallization (DRX) of hot deformed GH625 superalloy was investigated by optical microscope (OP) and transmission electron microscope (TEM). Hot compression tests were conducted using Gleeble-1500 simulator. It was found that the nucleation mechanism of DRX for the alloy deformed at 1150°C is composed of discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) in the vicinity of the serrated grain boundaries. With the increasing strain, the fraction of the DRX grains increases, while the size of the DRX grains almost remains in the same range. As the deformation temperature increasing, the size and fraction of the DRX grains increase, and no precipitation of intergranular carbides are found when the deformation temperature increases to 1150°C. At lower strain rate, the size and volume fraction of DRX grains decrease with the increasing strain rates. However, the size and volume fraction of DRX grains increase at higher strain rates due to the deformation thermal effect.

Using Split Hopkinson Pressure Bars to Perform Large Strain Compression Tests on Neoprene at Intermediate and High Strain Rates

2013 ◽  
Vol 631-632 ◽  
pp. 458-462 ◽  
Author(s):  
Peng Duo Zhao ◽  
Yu Wang ◽  
Jian Ye Du ◽  
Lei Zhang ◽  
Zhi Peng Du ◽  
...  
Keyword(s):  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Large Strain ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Compression Tests ◽  
Hopkinson Pressure Bar ◽  
High Strain Rates ◽  
Split Hopkinson ◽  
Pressure Bar

The strain rate sensitivity of neoprene is characterized using a modified split Hopkinson pressure bar (SHPB) system at intermediate (50 s-1, 100 s-1) and high (500 s-1, 1000 s-1) strain rates. We used two quartz piezoelectric force transducers that were sandwiched between the specimen and experimental bars respectively to directly measure the weak wave signals. A laser gap gage was employed to monitor the deformation of the sample directly. Three kinds of neoprene rubbers (Shore hardness: SHA60, SHA65, and SHA70) were tested using the modified split Hopkinson pressure bar. Experimental results show that the modified apparatus is effective and reliable for determining the compressive stress-strain responses of neoprene at intermediate and high strain rates.

scholarly journals Strain Compensation Constitutive Model and Parameter Optimization for Nb-Contained 316LN

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 212 ◽  
Author(s):  
Jingdan Li ◽  
Jiansheng Liu
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Compression Tests ◽  
Continuous Dynamic Recrystallization ◽  
Transmission Electron ◽  
Strain Compensation ◽  
Temperature Ranges ◽  
Continuous Dynamic

Hot deformation behavior of Nb-contained 316LN was investigated using a series of compression tests performed on a Gleeble-1500D simulator at temperature of 950–1200 °C and strain rate of 0.01~1 s−1. Based on the strain compensation method, a modified Arrhenius constitutive model considering the comprehensive effects of temperature, strain rate, and strain on flow stress was established, and the accuracy of the proposed model was evaluated by introducing correlation coefficient (R) and average relative error (AARE). The values of R and AARE were calculated as 0.995 and 4.48%, respectively, proving that the modified model has a high accuracy in predicting the flow stress of Nb-contained 316LN. The microstructure evolution and the dynamic recrystallization (DRX) mechanism of the experimental material were explicated by optical microscopy (OM), electron back scattered diffraction (EBSD), and transmission electron microscopy (TEM). It was found that continuous dynamic recrystallization (CDRX) characterized by subgrain evolution and discontinuous dynamic recrystallization (DDRX) featured by grain boundary nuclei are two main dynamic recrystallization (DRX) mechanisms of Nb-contained 316LN. Furthermore, based on the results of microstructure analyses, optimum parameters were obtained as temperature ranges of 1100~1200 °C and strain rate ranges of 0.01~1 s−1.

Geometric Dynamic Recrystallization in an AA2219 Alloy Deformed to Large Strains at an Elevated Temperature

2004 ◽  
Vol 467-470 ◽  
pp. 1199-1204 ◽  
Author(s):  
Rustam Kaibyshev ◽  
I. Mazurina ◽  
Oleg Sitdikov
Keyword(s):  
Dynamic Recrystallization ◽  
Equal Channel Angular Extrusion ◽  
Large Strains ◽  
Specific Process ◽  
Continuous Dynamic Recrystallization ◽  
Aa2219 Alloy ◽  
Continuous Dynamic ◽  
The Stability ◽  
Average Size ◽  
Zr Alloy

The mechanism of new grain evolution during equal channel angular extrusion (ECAE) up to a total strain of ~12 in an Al-Cu-Mn-Zr alloy at a temperature of 475oC (0.75Tm) was examined. It was shown that the new grains with an average size of about 15 µm result from a specific process of geometric dynamic recrystallization (GRX) which can be considered as a type of continuous dynamic recrystallization (CDRX). This process involves three elementary mechanisms. At moderate strains, extensive elongation of initial grains takes place; old grain boundaries become progressively serrated. Upon further ECAE processing, transverse low-angle boundaries (LAB) with misorientation ranging from 5 to 15o are evolved between grain boundary irregularities subdividing the initial elongated grains on crystallites with essentially equiaxed shape. The misorientation of these transverse subboundaries rapidly increases with increasing strain, resulting in the formation of true recrystallized grains outlined by high-angle boundaries from all sides. In the same time, the average misorientation of deformation-induced boundaries remains essentially unchanged during ECAE. It is caused by the fact that the evolution of LABs with misorientation less than 4o occurs continuously during severe plastic deformation. The mechanism maintaining the stability of the transverse subboundaries that is a prerequisite condition for their further transformation into highangle boundaries (HABs) is discussed.

Investigation on Dynamic Recrystallization Behavior in Hot Deformed Superalloy Inconel 718

2007 ◽  
Vol 546-549 ◽  
pp. 1297-1300 ◽  
Author(s):  
Y. Wang ◽  
Wen Zhu Shao ◽  
Liang Zhen ◽  
L. Lin ◽  
Y.X. Cui
Keyword(s):  
Dynamic Recrystallization ◽  
Inconel 718 ◽  
High Angle ◽  
Twin Boundaries ◽  
Continuous Dynamic Recrystallization ◽  
Subgrain Rotation ◽  
Dynamic Recrystallization Behavior ◽  
Ebsd Technique ◽  
Continuous Dynamic ◽  
The Individual

The nucleation and development of dynamic recrystallization (DRX) in hot deformed superalloy Inconel 718 during uniaxial compression were investigated by optical microscopy and electron back-scattered diffraction (EBSD) technique. The results showed that the discontinuous dynamic recrystallization was the predominant DRX mechanism in this alloy. The variations of partial crystallographic orientations led to the individual nucleation inside the deformed grains, which implied the occurrence of local continuous dynamic recrystallization. The progressive subgrain rotation can be confirmed neither near the prior high angle grain boundaries nor within the original grains. It was found that, as the strain increased, the initial twin boundaries were gradually transformed to ordinary mobile high angle boundaries. Meanwhile, the new twin boundaries were formed inside the recrystallized grain necklaces. It was suggested that the characteristics of the twin boundaries evolution with increasing strain were associated with the transformation of initial twin boundaries as well as the generation of new ones, which resulted in the development of DRX.

Dynamic Recrystallization Behavior of Biomedical CCM Alloys in Hot Compression Process

2010 ◽  
Vol 654-656 ◽  
pp. 1275-1278 ◽  
Author(s):  
Yun Ping Li ◽  
Shingo Kurosu ◽  
Emi Onodera ◽  
Hiroaki Matsumoto ◽  
Akihiko Chiba
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Forging ◽  
Stacking Faults ◽  
Recrystallization Behavior ◽  
Compression Tests ◽  
Compression Process ◽  
Continuous Dynamic Recrystallization ◽  
Computer Aided ◽  
Dynamic Recrystallization Behavior ◽  
Continuous Dynamic

Dynamic recrystallization behavior of Co-29Cr-6Mo-0.16N alloy was analyzed in details. Compression tests were carried out in a computer aided Thermecmaster- Z hot forging simulator. The results showed that uniformly distributed superfine grain size could be obtained by continuous dynamic recrystallization (DRX) process; Texture-free microstructure with uniformly distributed equiaxed fine grains was obtained. The formation of profuse stacking faults and their subsequent intersections are considered to be the principle mechanisms of DRX.

scholarly journals Review on Dynamic Recrystallization of Martensitic Stainless Steels during Hot Deformation: Part I—Experimental Study

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 572
Author(s):  
Hamed Aghajani Derazkola ◽  
Eduardo García Gil ◽  
Alberto Murillo-Marrodán ◽  
Damien Méresse
Keyword(s):  
Dynamic Recrystallization ◽  
Stainless Steels ◽  
Hot Deformation ◽  
Large Strains ◽  
Microstructural Changes ◽  
Ultrafine Grains ◽  
Microstructure Changes ◽  
Continuous Dynamic Recrystallization ◽  
Martensitic Stainless Steels ◽  
Continuous Dynamic

The evolution of the microstructure changes during hot deformation of high-chromium content of stainless steels (martensitic stainless steels) is reviewed. The microstructural changes taking place under high-temperature conditions and the associated mechanical behaviors are presented. During the continuous dynamic recrystallization (cDRX), the new grains nucleate and growth in materials with high stacking fault energies (SFE). On the other hand, new ultrafine grains could be produced in stainless steel material irrespective of the SFE employing high deformation and temperatures. The gradual transformation results from the dislocation of sub-boundaries created at low strains into ultrafine grains with high angle boundaries at large strains. There is limited information about flow stress and monitoring microstructure changes during the hot forming of martensitic stainless steels. For this reason, continuous dynamic recrystallization (cDRX) is still not entirely understood for these types of metals. Recent studies of the deformation behavior of martensitic stainless steels under thermomechanical conditions investigated the relationship between the microstructural changes and mechanical properties. In this review, grain formation under thermomechanical conditions and dynamic recrystallization behavior of this type of steel during the deformation phase is discussed.

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