scholarly journals Correlation among the Power Dissipation Efficiency, Flow Stress Course, and Activation Energy Evolution in Cr-Mo Low-Alloyed Steel

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3480
Author(s):  
Petr Opěla ◽  
Ivo Schindler ◽  
Petr Kawulok ◽  
Rostislav Kawulok ◽  
Stanislav Rusz ◽  
...  
Keyword(s):  
Activation Energy ◽  
Flow Stress ◽  
Power Dissipation ◽  
Hot Compression ◽  
Alloyed Steel ◽  
Approximation Procedure ◽  
Processing Maps ◽  
Energy Evolution ◽  
Power Dissipation Efficiency ◽  
Low Alloyed Steel

In the presented research, conventional hot processing maps superimposed over the flow stress maps or activation energy maps are utilized to study a correlation among the efficiency of power dissipation, flow stress, and activation energy evolution in the case of Cr-Mo low-alloyed steel. All maps have been assembled on the basis of two flow curve datasets. The experimental one is the result of series of uniaxial hot compression tests. The predicted one has been calculated on the basis of the subsequent approximation procedure via a well-adapted artificial neural network. It was found that both flow stress and activation energy evolution are capable of expressing changes in the studied steel caused by the hot compression deformation. A direct association with the course of power dissipation efficiency is then evident in the case of both. The connection of the presence of instability districts to the activation energy evolution, flow stress course, and power dissipation efficiency was discussed further. Based on the obtained findings it can be stated that the activation energy processing maps represent another tool for the finding of appropriate forming conditions and can be utilized as a support feature for the conventionally-used processing maps to extend their informative ability.

scholarly journals Hot Deformation Behavior and Processing Maps of a New Ti-6Al-2Nb-2Zr-0.4B Titanium Alloy

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2456
Author(s):  
Zhijun Yang ◽  
Weixin Yu ◽  
Shaoting Lang ◽  
Junyi Wei ◽  
Guanglong Wang ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Constitutive Equation ◽  
Deformation Mechanism ◽  
Power Dissipation ◽  
Hot Deformation ◽  
Dissipation Rate ◽  
Dynamic Recovery ◽  
Processing Maps ◽  
Temperature Range

The hot deformation behaviors of a new Ti-6Al-2Nb-2Zr-0.4B titanium alloy in the strain rate range 0.01–10.0 s−1 and temperature range 850–1060 °C were evaluated using hot compressing testing on a Gleeble-3800 simulator at 60% of deformation degree. The flow stress characteristics of the alloy were analyzed according to the true stress–strain curve. The constitutive equation was established to describe the change of deformation temperature and flow stress with strain rate. The thermal deformation activation energy Q was equal to 551.7 kJ/mol. The constitutive equation was ε ˙=e54.41[sinh (0.01σ)]2.35exp(−551.7/RT). On the basis of the dynamic material model and the instability criterion, the processing maps were established at the strain of 0.5. The experimental results revealed that in the (α + β) region deformation, the power dissipation rate reached 53% in the range of 0.01–0.05 s−1 and temperature range of 920–980 °C, and the deformation mechanism was dynamic recovery. In the β region deformation, the power dissipation rate reached 48% in the range of 0.01–0.1 s−1 and temperature range of 1010–1040 °C, and the deformation mechanism involved dynamic recovery and dynamic recrystallization.

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 ◽  
...  
Keyword(s):  
Flow Stress ◽  
Power Dissipation ◽  
Deformation Behavior ◽  
Processing Map ◽  
Flow Instability ◽  
True Strain ◽  
Processing Condition ◽  
Strain Rates ◽  
Processing Maps ◽  
Nickel Based Superalloy

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.

Study on Hot Processing Maps and Flow Instability of 1235 Al Alloy Treated by Different Methods of Purification

2011 ◽  
Vol 399-401 ◽  
pp. 1870-1877
Author(s):  
Gao Sheng Fu ◽  
Wen Duan Yan ◽  
Hong Ling Chen ◽  
Gui Qing Chen ◽  
Chao Zeng Cheng
Keyword(s):  
Strain Rate ◽  
Power Dissipation ◽  
Flow Instability ◽  
Al Alloy ◽  
Processing Maps ◽  
Hot Workability ◽  
Optimum Processing ◽  
Lower Strain ◽  
Power Dissipation Efficiency ◽  
Higher Temperature

Based on the theory of processing map proposed by PRASAD, the power dissipation maps, the hot deformation instability maps and the hot processing maps of 1235 Al alloys treated by different methods of purification were built, and the effects of purification and deformation conditions at elevated-temperature on hot workability of 1235 Al alloy were analyzed. At the same time the optimum processing region and flow instability region were determined. The results show that the hot processing map of 1235 Al alloy has two instability zones in the temperature range of 300-500°C and in the strain rate ranging from 0.01s-1to 10.0s-1up to a true strain of 0.7, that is, one zone lying in the range of lower temperature and higher strain rate, the other zone in the range of higher temperature and mid strain rate. The purification effect has significant impact on hot workability of the alloy. It is found that the optimum processing region of 1235 Al alloy treated by high-efficient purification treatment is present in the range of higher temperature and lower strain rate zone, and its power dissipation efficiency is about 46%; while the optimum processing region of 1235 Al alloys treated by conventional refining treatment is present in the range of mid-temperature and lower strain rate zone or in the range of higher temperature and strain rate zone, and its power dissipation efficiency is about 23-29%. The results of observation of the deformation microstructure of 1235 Al alloy are in accordance with that of the hot processing maps of the alloy, thus showing that the calculation results of the hot processing maps are reliable.

Hot Workability Analysis of Extruded Mg-Zn-Mn-Y Magnesium Alloys with Different Phases

2012 ◽  
Vol 184-185 ◽  
pp. 1010-1016
Author(s):  
Wei Wei He ◽  
Kun Zhang ◽  
Min Huang ◽  
Sheng Long Dai
Keyword(s):  
Strain Rate ◽  
Magnesium Alloys ◽  
Power Dissipation ◽  
Rate Sensitivity ◽  
Processing Maps ◽  
Hot Workability ◽  
Compression Tests ◽  
Secondary Phases ◽  
Forming Process ◽  
Power Dissipation Efficiency

Workability, an important parameter in magnesium alloys forming process, can be evaluated by means of processing maps on the basis of dynamic materials model, constructed from experimentally generated flow stress variation with respect to strain, strain rate and temperature. To obtain the processing maps of extruded Mg-Zn-Mn-Y magnesium alloy with different secondary phases (I-phase and W-phase), hot compression tests were performed over a range of temperatures 523–673 K and strain rates 0.001~10s-1. The response of strain-rate sensitivity (m-value), power dissipation efficiency (ζ-value) and instability parameter (n-value) to temperature and strain rate were evaluated. By the superimposition of the power dissipation and the instability maps, the dynamic recrystallization (DRX) and instability zones were identified and validated through micrographs. The observations were performed in order to describe the behavior of the material under hot forming operation in terms of material damage and micro-structural modification.

Hot Deformation and Processing Map of C919 Aluminum Alloy

2015 ◽  
Vol 816 ◽  
pp. 810-817
Author(s):  
Yong Biao Yang ◽  
Zhi Min Zhang ◽  
Xing Zhang
Keyword(s):  
Aluminum Alloy ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Testing Machine ◽  
Strain Rate Range ◽  
Hot Compression ◽  
Strain Rates ◽  
Processing Maps ◽  
Compression Tests

The hot deformation behaviors of Aluminum alloy C919 were studied in the present investigation. The hot compression tests for C919 were carried out in the temperature range of 350°C~470°C and strain rates range of 0.001s-1~1s-1 using GLEEBLE-1500 thermal simulate testing machine. Optical microscopy (OM) was used for the microstructure characterization. The experimental results showed that the flow stress of C919 aluminum alloy decreased with increasing temperature and decreasing strain rates and the flow stress curves tended to increase at a strain rate of 1s-1 with increasing strain, while the flow stresses kept with increasing strain at lower strain rate. The alloys were more prone to dynamic recrystallization with decreasing strain rates during hot deformation. The hot compression behavior of C919 aluminum alloy can be described as hyperbolic sine function corrected Arrhenius relation. The processing maps for the alloy were built at a strain of 0.6. The instability deformation domain occurred at temperatures range from 350°C and 380°C and at a strain rate of 0.1-1s-1. Based on the processing maps and microstructure observations, the optimum hot-working parameters were determined to be at a temperature of 470°C in the strain rate range from 0.1-0.01s−1 for the C919 aluminum alloy.

Characterization of Hot Deformation Behavior of Zr-1.0Sn-0.3Nb-0.3Fe-0.1Cr Using Processing Map

2013 ◽  
Author(s):  
B. F. Luan ◽  
R. S. Qiu ◽  
Z. Zhou ◽  
K. L. Murty ◽  
J. Zhou ◽  
...  
Keyword(s):  
Activation Energy ◽  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
True Strain ◽  
Compression Testing ◽  
Strain Rates ◽  
Processing Maps ◽  
Deformation Activation Energy

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.

scholarly journals Flow Stress Modelling and 3D Processing Maps of Al4.5Zn4.5Mg1Cu0.12Zr Alloy with Different Scandium Contents

2021 ◽  
Vol 11 (10) ◽  
pp. 4587
Author(s):  
Maxim G. Khomutov ◽  
Andrey V. Pozdniakov ◽  
Alexander Yu. Churyumov ◽  
Ruslan Yu. Barkov ◽  
Alexey N. Solonin ◽  
...  
Keyword(s):  
Flow Stress ◽  
Deformation Behaviour ◽  
Three Dimensional ◽  
Processing Maps ◽  
Hollomon Parameter ◽  
Stability Diagrams ◽  
Power Dissipation Efficiency ◽  
3D Processing ◽  
Hot Deformation Behaviour ◽  
Flow Stress Model

The hot deformation behaviour of an Al4.5Zn4.5Mg1Cu0.12Zr based alloy with 0.05, 0.1 and 0.15% Sc was investigated at temperatures between 300–450 °C and a strain rate of 0.1–15 s−1. The materials constants of a flow stress model based on the Zener-Hollomon parameter were determined (AARE was 5.8%). Three-dimensional processing maps were established by combining power dissipation efficiency and flow stability diagrams. Based on processing maps analysis and microstructures investigations, the optimal deformation parameters were determined as a temperature range of 350–400 °C and strain rates of 0.1–1 s−1 for the alloys with 0.05% and 0.1% Sc, and 0.1 s−1 for the alloy with 0.15% Sc.

scholarly journals Microstructure Evolution and Hot Deformation Behavior of a CuNiSn Alloy

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 451
Author(s):  
Yexin Jiang ◽  
Xu Wang ◽  
Zhou Li ◽  
Zhu Xiao ◽  
Xiaofei Sheng ◽  
...  
Keyword(s):  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Power Dissipation ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Flow Instability ◽  
True Strain ◽  
Hot Deformation Behavior ◽  
Power Dissipation Efficiency

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.

scholarly journals Multi-directional Forging of Large-Scale Mg-9Gd-3Y-2Zn-0.5Zr Alloy Guided By 3D Processing Maps And Finite Element Analysis

2021 ◽  
Author(s):  
Jiyu Li ◽  
Shuai Dong ◽  
Chaoyu Zhao ◽  
Jian Zeng ◽  
Li Jin ◽  
...  
Keyword(s):  
Finite Element ◽  
Power Dissipation ◽  
Large Scale ◽  
Material Model ◽  
Processing Maps ◽  
Compression Tests ◽  
Element Analysis ◽  
Homogeneous Microstructure ◽  
Power Dissipation Efficiency ◽  
3D Processing

Abstract The three-dimensional (3D) processing maps of cast Mg-9.0Gd-3.0Y-2.0Zn-0.5Zr alloy were established based on isothermal compression tests and dynamic material model (DMM). The stable and power efficient forming domains were determined by considering both the instability and power dissipation efficiency maps. Multi-directional forging (MDF) was then simulated by employing finite element (FE) analysis in the Deform-3D software, using the 3D power dissipation efficiency maps as input. The optimal forging parameters were thus obtained for a large-scale ingot with 430 mm in diameter and 440 mm in height, i.e. a forging temperature of 450 ℃ and forging speed of 10 mm/s. Finally, a Mg-9.0Gd-3.0Y-2.0Zn-0.5Zr cake-shaped forged part with 900 mm in diameter and 100 mm in height was produced. After T6-heat treatment, the edge and center of the forged part exhibit homogeneous microstructure and relatively consistent properties, with the tensile strength, yield strength and elongation being about 400 MPa, 320 MPa and 14.0% respectively. Using transmission electron microscopy, the main strengthening phases were revealed to be the dense nano-scale β' phases that are uniformly distributed inside the material.

Characterization of Hot Deformation of Nb-V-Ti Microalloyed Steel Using Processing Map

2009 ◽  
Vol 79-82 ◽  
pp. 1439-1442
Author(s):  
Song Xiang ◽  
Guo Quan Liu
Keyword(s):  
Strain Rate ◽  
Power Dissipation ◽  
Hot Deformation ◽  
Microalloyed Steel ◽  
Rate Sensitivity ◽  
Strain Rate Range ◽  
Processing Maps ◽  
Peak Efficiency ◽  
Power Dissipation Efficiency ◽  
Working Parameters

The hot deformation behavior of Nb-V-Ti microalloyed steel in the temperature range of 850°C～1100°C and the strain rate range of 0.001s-1～30s-1 was investigated by establishing the processing maps. The strain rate sensitivity (m), power dissipation efficiency (η) and instability parameter were calculated based on the experimental compression data and are plotted in the temperature–strain rate plane to obtain power dissipation and instability maps. The processing maps exhibit that the deformation at 1000°C and 2s-1 is one peak efficiency of power dissipation of 21%, the deformation at 1050°C and 0.01~0.001 s-1 is another peak efficiency of power dissipation of 45%. The optical microstructure observations show that they represent two dynamic recrystallization domains. Based on the above processing maps, the hot working parameters were optimized.

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