scholarly journals Investigation on the Thermal Deformation Behavior of the Nickel-Based Superalloy Strengthened by γ′ Phase

Crystals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 125
Author(s):  
Haiping Wang ◽  
Dong Liu ◽  
Jianguo Wang ◽  
Yongzhao Shi ◽  
Yong Zheng ◽  
...  

The isothermal compression tests of the nickel-based superalloy Waspaloy were carried out under various temperatures from 1040 to 1120 °C and strain rates from 0.01 to 10 s−1 with the height reduction of 60% and the flow stress curves were obtained. The curves show that the flow stress is greatly affected by the temperature and strain rates. Regression analysis of the experimental results was carried out to learn about the deformation behavior through the Arrhenius equation and came to the conclusion that the activation energy of Waspaloy is 669.7 kJ/mol. The constitutive equation of the Waspaloy was constructed. Meanwhile, the processing maps of the Waspaloy for the power dissipation and the flow instability were constructed. The processing map of the power dissipation and the flow instability depicts that the strain plays a major role in the processing maps. The instability zone is prone to appear at higher strain rates with the increasing strains. According to the instability processing map, there are three unsafe regimes around 1040–1120 °C/1.5–10 s−1, 1040–1080 °C/0.02–0.1 s−1 and 1110–1120 °C/0.02–0.3 s−1 that should be avoided during deformation process. The power dissipation maps show that the maximum dissipation is prone to appear at low strain rates (0.01 s−1) when the strain is about 0.1~0.6 while at middle strain rates (0.1–1 s−1) when the strain is over 0.6, and when the true strain is 0.9, the optimum processing condition is around 1060–1120 °C/0.1–1 s−1. The dynamic microstructures under different temperatures and strain rates were also obtained. We concluded that lower strain rates and higher temperatures are more applicable to obtain fully-recrystallized microstructures. Based on the instability maps and the power dissipation maps and the dynamic microstructures, the optimum deformation conditions are determined to be around 1080–1100 °C/0.1–1 s−1 and 1040–1120 °C/0.01 s−1.

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 451
Author(s):  
Yexin Jiang ◽  
Xu Wang ◽  
Zhou Li ◽  
Zhu Xiao ◽  
Xiaofei Sheng ◽  
...  

The hot deformation behavior of Cu-20.0Ni-5.0Sn-0.25Zn-0.22Mn was investigated using a Gleeble-3500 thermal simulator with a temperature range from 720 °C to 880 °C and a strain rate range from 0.001 s−1 to 1 s−1. The results show that the flow stress increased with the increase of the strain rate and the decrease of the temperature. The constitutive equation of the alloy was established based on the peak flow stress. Figures of the power dissipation efficiency and flow instability with the variable of the true strain from 0.2 to 0.8 displayed the dynamic change of power dissipation efficiency and the instability area. The domain of 730–770 °C and 0.001–0.01 s−1 possessed a power dissipation efficiency over 40% throughout the whole deformation. The flow instability always appeared at a high strain rate from 0.1 s−1 to 1 s−1 during the whole deformation process. The nucleation site of the dynamic recrystallization generally appeared along the grain boundaries, indicating the discontinuous dynamic recrystallization mechanism. The appropriate conditions for deformation with a true strain of 0.9 is in a safe domain (820–860 °C with a strain rate of 0.001–0.01 s−1). There were four kinds of variation tendencies of the power dissipation efficiency with the increase of the true strain under various conditions, suggesting a changing situation for the main softening mechanisms.


2014 ◽  
Vol 906 ◽  
pp. 254-258
Author(s):  
Yan Hui Liu ◽  
Ze Kun Yao ◽  
Yong Quan Ning ◽  
Hong Zhen Guo ◽  
Zhang Long Zhao

Isothermal compression tests were carried out on Ti-6.0Al-7.0Nb biomedical titanium alloy at the temperatures of 750900°C (all below β phase transition temperature about 1010°C) and strain rates of 0.0011.0s-1. The processing maps were constructed to evaluate the efficiency of power dissipation (η) and recognize the flow instability regimes. True strain takes great effect on the efficiency of power dissipation η under the different temperatures and strain rates. The value of power dissipation η increases from 0.1 to 0.7 in most areas. When the strain is 0.9, the value of power dissipation η in most regimes is from 30% to 40%. There are two instability regimes respectively located around 780°C/1.0s-1 and 860-900°C/0.001-0.01s-1 when the strains are below 0.5. One of the instability regimes disappears when the strains are 0.5-0.7. When the strain is 0.9, there are still two instability regimes. The safe regime located around 780-840°C/0.1-0.01s-1, and hot deformation can be carried out in this area.


2018 ◽  
Vol 913 ◽  
pp. 30-36
Author(s):  
Ran Liu ◽  
Hui Huang ◽  
Ya Liu ◽  
Li Rong

To study the hot deformation behavior of Al-Mg-Er alloy, hot compression tests were conducted on a Gleeble-1500D thermal simulator at the temperature range of 200-500°C with the strain rates from 0.001 to 10s-1. With the increase in the deformation temperature and the decrease in strain rates, the flow stress of the Al-Mg-Er alloy decreased. Processing maps were constructed to study on hot workability characteristics. The results showed that the flow stress curves exhibited the typical dynamic recrystallization characteristics and the stress decreased with the increase of deformation temperature and the decrease of strain rate. Moreover, the processing maps were established on the basis of dynamic material model and Prasad’s instability criterion.


2013 ◽  
Vol 274 ◽  
pp. 427-431 ◽  
Author(s):  
Ying Gong

The compression test on TC21 titanium alloy was carried out in the temperature range of 860~940oC and the strain rate range of 0.01~10s-1 on Gleeble-1500D hot simulation machine. And the hot deformation behavior was studied. The processing map was calculated and analyzed according the dynamic materials model. It is found that the flow stress of TC21 decreases with the increasing of the temperature and the decreasing of the strain rate. The flow stress curves are characterized by steady state at low strain rate( s-1)but discontinuous yield at high strain rate( s-1). The processing map established at the true strain of 0.4 shows that there are three regions, instability and safe and peak region, and the efficiencies of power dissipation are 0~25%,31%~37% and 43%~49% respectively. The peak region is the optimum hot working zone of TC21 titanium alloy.


2013 ◽  
Vol 716 ◽  
pp. 240-243 ◽  
Author(s):  
Ching Hao Liao ◽  
Horng Yu Wu ◽  
Shyong Lee ◽  
Cheng Tao Wu ◽  
Chui Hung Chiu

Based on the experimental results from the hot compression tests of homogenized cast AZ61 Mg alloy, processing maps were constructed by superimposition of the instability maps over the power dissipation maps. The domain with the efficiency of power dissipation reaching a local maximum and flow instability region were identified in the processing maps. The processing map obtained at a strain of 0.6 exhibited only one domain with local maximum efficiency of power dissipation. The microstructure observations showed that variation in microstructure was related to the deformation condition, which was associated with the variation in efficiency of power dissipation.


Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1940 ◽  
Author(s):  
Jianmei Kang ◽  
Yuhui Wang ◽  
Zhimeng Wang ◽  
Yiming Zhao ◽  
Yan Peng ◽  
...  

Hot deformation behavior of Fe-30Mn-0.11C steel was investigated. Hot compression tests were carried out at various temperatures ranging from 800 °C to 1200 °C and at different strain rates of 0.01 s−1 to 10 s−1. The constitutive equation based on peak stress was established. Hot processing maps at different strains and recrystallization diagrams were also established and analyzed. The results show that dynamic recrystallization easily occur at high deformation temperatures and low strain rates. Safe and unstable zones are determined at the true strain of 0.6 and 0.7, and the hot deformation process parameters of partial dynamic recrystallization of the tested steel are also obtained.


2014 ◽  
Vol 941-944 ◽  
pp. 1459-1462
Author(s):  
Guo Bao Yang ◽  
Ze Kun Yao ◽  
Yan Hui Liu ◽  
Yang Nan ◽  
Yong Quan Ning

Isothermal compression tests were carried out on GH4133B superalloy at 940–1060°C (below nominal γ΄-transus temperature of 1080°C) and 0.001–1.0s-1. The processing maps were constructed to evaluate the efficiency of power dissipation (η) and recognize the flow instability regimes. Our investigations demonstrate that true strain takes great effect on processing maps' evolution. At 1020°C/1.0s-1, the efficiency valueηundergoes a small decline at low strains, and then increases linearly from 0.26 to 0.58 at high strains. However, the efficiency value remains high constant (η=0.40) with the increased strain under the condition of 980°C/0.001s-1. As a result, hot deformation can be carried out firstly at 980°C/0.001s-1with small strain about 0.35 and then carried out at 1020°C/1.0s-1to get fine homogeneous microstructure. There are two instability regimes respectively located around 940°C/1.0s-1and 1060°C/0.001s-1when the strains are 0.05–0.40. Moreover, there is another instability regime located around 1060°C/1.0s-1when the strains are 0.45–0.69.


2017 ◽  
Vol 62 (1) ◽  
pp. 59-65
Author(s):  
A. Łukaszek-Sołek ◽  
A. Świątoniowski ◽  
K. Celadyn ◽  
J. Sińczak

Abstract In this paper, the results of investigations into, and of the analyses of, the hot deformation behaviour of the Ni50Cr45N0.6 alloy were presented. Compression tests were conducted on a Gleeble 3800 thermo-mechanical simulator within the following temperatures range 850-1200°C and within that of the strain rate 1-40 s-1 to the constant true strain of 0.9, for the purpose of fulfilling the objective of obtaining experimental stress date. Those data were taken advantage of for the purpose of calculating the workability parameters, and that means the efficiency of power dissipation η, the flow instability ξ and the strain rate sensitivity m. The processing maps based upon Murty’s criterion were drawn up for the following true strain range: 0.2-0.9, and, subsequently, both processing windows and the flow instability areas were determined. For the alloy being analysed, the most advantageous conditions of metal forming were ascertained within the following range of temperatures: 950-1000°C, and for that of the strain rate amounting to 10-40 s-1, and that because of (occurring at the temperature of 950°C) the peak of the efficiency of power dissipation parameter η, amounting to 22% (in accordance with Murty’s criterion). The flow instability areas identified on the processing maps ought to be avoided in metal forming processes. Experimental rolling tests were also conducted.


Author(s):  
B. F. Luan ◽  
R. S. Qiu ◽  
Z. Zhou ◽  
K. L. Murty ◽  
J. Zhou ◽  
...  

Hot deformation characteristics of forged and β-quenched Zr-1.0Sn-0.3Nb-0.3Fe-0.1Cr (N18 alloy) in the temperature range 625–950°C and in the strain rate range 0.005–5 s−1 have been studied by uniaxial compression testing of Gleeble 3500. For this study, the approach of processing maps has been adopted and their interpretation done using the Dynamic Materials Model (DMM). Based on a series of true stress-true strain curves on various temperatures and strain rates, the flow stress has been summarized and both the strain rate sensitivity index (m) and deformation activation energy (Q) have been calculated by the constitutive equations that flow stress and the relationship of Z parameter and flow stress have been established subsequently. Furthermore, the efficiency of power dissipation (⬜) given by [2m/(m+1)] and improved by Murty has been plotted as a function of temperature and strain rate to obtain different processing maps at different true strain rates ranging from 0.1–0.7. Subsequently, the microstructures of the specimens after compression testing were characterized by electron channeling contrast (ECC) imaging techniques used an FEI Nova 400 field emission gun scanning electron microscopy (FEG-SEM). The results showed that: (i) The hyperbolic sine constitutive equation can describe the flow stress behavior of zirconium alloy, and the deformation activation energy and flow stress equation were calculated under the different temperature stages which insists that the deformation mechanism is not dynamic recovery. (ii) The hot processing maps and its validation were analyzed, which indicated that the DMM theory was reliable and could be adopted as useful tool for optimizing hot workability of Zr. The optimum parameters for extrusion and hammer forging were revealed on the processing maps of 830–950°C, 0.048–2.141 s−1 and 916–950°C, 2.465–5 s−1. (iii) The microstructure of the ingot exhibits a typical lamellar Widmanstatten structure. Under the different strain rates, the grains formed by dynamic recrystallization existed normally in the central zone of the compression samples while the no uniformity of grain size increased with the increasing of strain rate. Meanwhile, due to the dynamic recrystallization as a thermal activation process, the grains size and uniformity increased with the increasing of temperature. In brief, microstructure analysis showed that continuous dynamic recrystallization and geometric dynamic recrystallization operated concurrently during the isothermal compressive deformation.


Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 911
Author(s):  
Guo Li ◽  
Xingyu Bai ◽  
Qiang Peng ◽  
Guobing Wei ◽  
Zhenduo Ma

High-temperature compression tests with dual-phase Mg-6Li alloy were conducted on the Gleeble-3500 thermal-mechanical simulator. Flow stress and micro-structure evolution were analyzed for temperatures (T = 423, 473,523 and 573 K) and strain rates (ε˙= 0.001, 0.01, 0.1 and 1 s−1). On this basis, the constitutive model and hot processing maps were established. Besides, the dynamic re-crystallization (DRX) of α-Mg phase, grain orientation and texture composition under different deformation conditions were analyzed by EBSD technology. The experimental results show that the flow stress of Mg-6Li alloy increased with decreasing deformation temperature and increasing strain rate. In addition, the range of instability zone expanded with the increase of strain. The optimal thermal processing temperature was found to be in the range of 500 K–573 K, and the optimal strain rates were between 0.01 s−1–1 s−1. Model-predicted stress values were compared with experimental values for model verification. The 0.9954 correlation coefficient and the 5.48% average absolute relative error shown by the calculation indicate an acceptable accuracy of the model in predicting thermal deformation behavior of Mg-6Li alloy. Moreover, based on our EBSD data and maps analysis, the DRX proportion of α-Mg phase in Mg-6Li alloy was relatively low, and α-Mg phase formed <0001>//CD basal texture.


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