Constitutive Equation and Dynamic Softening Behavior of 7A55 Aluminum Alloy during Compression at Elevated Temperatures

2017 ◽  
Vol 898 ◽  
pp. 291-299
Author(s):  
Di Feng ◽  
Xin Ming Zhang ◽  
Sheng Dan Liu
Keyword(s):  
Aluminum Alloy ◽  
Constitutive Equation ◽  
Strain Rate ◽  
Hot Deformation ◽  
Elevated Temperatures ◽  
Boundary Migration ◽  
Compression Tests ◽  
Softening Mechanism ◽  
Softening Behavior ◽  
Deformation Behaviors

The hot deformation behaviors of 7A55 aluminum alloy were investigated by compression tests at temperatures ranging from 270°C to 450°C and strain rate ranging from 0.1s−1 to 25s−1. Tha rResults show that the flow stress increased with increasing strain rate and decreasing temperature. A two-stage constitutive equation was established and the hot deformation activation energy was 140 kJ/mol. EBSD observations show that the fine and equiaxed grains with the misorientation angle above 15° nucleated at the initial grain boundaries under high temperature and low strain rate conditions. It is concluded that the softening mechanism of 7A55 aluminum alloy is dynamic recovery (DRV), together with a partial dynamic recrystallization (DRX). The nucleation mechanism of DRX could be explained by the strain induced grain boundary migration (SIBM). The DRX softening model was established based on the dislocation density theory finally.

Hot Deformation Behavior and Constitutive Equation of 5E61 Aluminum Alloy

2017 ◽  
Vol 898 ◽  
pp. 9-16
Author(s):  
Ya Liu ◽  
Hui Huang ◽  
R. Liu ◽  
Sheng Ping Wen ◽  
Xiao Lan Wu ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Constitutive Equation ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
True Strain ◽  
Aluminum Matrix ◽  
Hot Deformation Behavior ◽  
Hollomon Parameter ◽  
Softening Mechanism

The hot deformation behavior of aluminum alloy 5E61 was studied by hot compressive tests using a Gleeble-1500 thermal simulator. The tests were performed at temperatures varying from 250°C to 500°C and strain rates ranging from 0.001 s-1 to 10s-1. The results achieved in the present study showed that the steady flow stress increases with decreasing temperature and increasing strain rate, in accordance with the Zener-Hollomon parameter. The related microstructure is sensitive to deformation temperature, strain rate and strain. The constitutive equation based on true stress-true strain curves has been developed by hyperbolic sine equation with the hot deformation activation energy of 153.907KJ/mol. The softening mechanism could be ascribed dominantly to dynamic recovery. The results of TEM observation suggested that Mn-containing particles and Al3(Er,Zr) phase have precipitated in the aluminum matrix and pin the dislocations, which could effectively inhibit the dynamic recrystallization.

Flow and Densification Behaviors of Sintered P/F-10C50 Steel under Hot Compression

2016 ◽  
Vol 849 ◽  
pp. 811-818
Author(s):  
Biao Guo ◽  
Chang Chun Ge ◽  
Yi Xu ◽  
Qiu Yan Lu ◽  
Sui Cai Zhang
Keyword(s):  
Constitutive Equation ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
Hot Compression ◽  
Compression Tests ◽  
Sintered Steel ◽  
Absolute Relative Error ◽  
Average Absolute Relative Error ◽  
Deformation Behaviors

The hot deformation and densification behaviors of sintered P/F-10C50 steel were investigated by hot compression tests on Gleeble-1500 thermal mechanical simulator at the temperature ranging from 900 °C to 1000 °C and the strain rate ranging from 0.1 s-1 to 10 s-1. The flow and densification characteristics of the tested specimens at different deformation temperatures and strain rates were studied. The flow stress of the sintered steel persistently increases until the end of the test as the result of matrix and geometric work hardening. The higher deformation temperature and strain rate are conductive to the healing of the pores and promote the densification of the sintered steel, while the higher deformation temperature and lower strain rate impede the densification. The constitutive equation of the sintered steel is established by the means of stepwise regression. The flow stresses predicted by the established constitutive equation are in good agreement with the experimental values, and the correlation coefficient (R) and the average absolute relative error (AARE) are 0.9931 and 3.52%, respectively. These results demonstrate the hot deformation behaviors of the sintered P/F-10C50 steel are excellently predicted by the established constitutive equation.

scholarly journals The Effect of α-Al(MnCr)Si Dispersoids on Activation Energy and Workability of Al-Mg-Si-Cu Alloys during Hot Deformation

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xiaoguo Wang ◽  
Jian Qin ◽  
Hiromi Nagaumi ◽  
Ruirui Wu ◽  
Qiushu Li
Keyword(s):  
Activation Energy ◽  
Aluminum Alloys ◽  
Constitutive Equation ◽  
Hot Deformation ◽  
Flow Instability ◽  
Void Formation ◽  
Activation Energies ◽  
Compression Tests ◽  
Softening Mechanism ◽  
Dynamic Softening

The hot deformation behaviors of homogenized direct-chill (DC) casting 6061 aluminum alloys and Mn/Cr-containing aluminum alloys denoted as WQ1 were studied systematically by uniaxial compression tests at various deformation temperatures and strain rates. Hot deformation behavior of WQ1 alloy was remarkably changed compared to that of 6061 alloy with the presence of α-Al(MnCr)Si dispersoids. The hyperbolic-sine constitutive equation was employed to determine the materials constants and activation energies of both studied alloys. The evolution of the activation energies of two alloys was investigated on a revised Sellars’ constitutive equation. The processing maps and activation energy maps of both alloys were also constructed to reveal deformation stable domains and optimize deformation parameters, respectively. Under the influence of α dispersoids, WQ1 alloy presented a higher activation energy, around 40 kJ/mol greater than 6061 alloy’s at the same deformation conditions. Dynamic recrystallization (DRX) is main dynamic softening mechanism in safe processing domain of 6061 alloy, while dynamic recovery (DRV) was main dynamic softening mechanism in WQ1 alloy due to pinning effect of α-Al(MnCr)Si dispersoids. α dispersoids can not only resist DRX but also increase power required for deformation of WQ1 alloy. The microstructure analysis revealed that the flow instability was attributed to the void formation and intermetallic cracking during hot deformation of both alloys.

Hot Deformation Behaviors of SiCp/Al Composites

2014 ◽  
Vol 1058 ◽  
pp. 165-169 ◽  
Author(s):  
Shi Ming Hao ◽  
Jing Pei Xie
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
True Strain ◽  
Constant Strain Rate ◽  
Hot Compression ◽  
Compression Tests ◽  
Sensitive Material ◽  
2024 Aluminum Alloy ◽  
Deformation Behaviors

The hot deformation behaviors of 30%SiCp/2024 aluminum alloy composites was studied by hot compression tests using Gleeble-1500 thermomechanical simulator at temperatures ranging from 350-500°C under strain rates of 0.01-10 s-1. The true stress-true strain curves were obtained in the tests. Constitutive equation and processing map were established. The results show that the flow stress decreases with the increase of deformation temperature at a constant strain rate, and increases with the increase of strain rate at constant temperature, indicating that composite is a positive strain rate sensitive material. The flow stress behavior of composite during hot compression deformation can be represented by a Zener-Hollomon parameter in the hyperbolic sine form. Its activation energy for hot deformation Q is 183.251 kJ/mol. The optimum hot working conditions for this material are suggested.

scholarly journals Constitutive Equation and Hot Processing Map of a Nitrogen-Bearing Martensitic Stainless Steel

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1502
Author(s):  
Xiao Li ◽  
Lifeng Hou ◽  
Yinghui Wei ◽  
Zhengyan Wei
Keyword(s):  
Stainless Steel ◽  
Constitutive Equation ◽  
Strain Rate ◽  
Hot Deformation ◽  
Processing Map ◽  
Martensitic Stainless Steel ◽  
True Strain ◽  
True Stress ◽  
Hot Working ◽  
Compression Tests

The hot deformation behavior of a nitrogen-bearing martensitic stainless steel was researched by the isothermal compression test in the temperature range of 950–1150 °C and strain rate range of 0.01–10 s−1 with a Gleeble-3800 thermal-mechanical simulating tester. A strain compensated sine-hyperbolic Arrhenius-type constitutive equation was developed to describe the relationship between true stress and deformation parameters such as temperature, strain rate and true strain. The hot deformation activation energy is calculated to be from 407 to 487 KJ mol−1. It is validated by the standard statistical parameters that the established constitutive equation can accurately predict the true stress. The processing maps at different true strains were constructed based on the dynamic material model (DMM) and the true stress data obtained from the hot compression tests. Two unstable regions which should be avoided during hot working were observed from the processing map. In addition, the optimum hot working parameters are located in the domain of 1000–1150 °C/0.1–1 s−1 with the peak power dissipation efficiency of 39.9%, in which complete dynamic recrystallization (DRX) occurs.

Modeling the Hot Deformation Behaviors of As-Extruded 7075 Aluminum Alloy by an Artificial Neural Network with Back-Propagation Algorithm

2017 ◽  
Vol 36 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Guo-zheng Quan ◽  
Zhen-yu Zou ◽  
Tong Wang ◽  
Bo Liu ◽  
Jun-chao Li
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Aluminum Alloy ◽  
Strain Rate ◽  
Hot Deformation ◽  
Back Propagation ◽  
Bp Algorithm ◽  
7075 Aluminum Alloy ◽  
Ann Model ◽  
Deformation Behaviors

AbstractIn order to investigate the hot deformation behaviors of as-extruded 7075 aluminum alloy, the isothermal compressive tests were conducted at the temperatures of 573, 623, 673 and 723 K and the strain rates of 0.01, 0.1, 1 and 10 s−1 on a Gleeble 1500 thermo-mechanical simulator. The flow behaviors showing complex characteristics are sensitive to strain, strain rate and temperature. The effects of strain, temperature and strain rate on flow stress were analyzed and dynamic recrystallization (DRX)-type softening characteristics of the flow behaviors with single peak were identified. An artificial neural network (ANN) with back-propagation (BP) algorithm was developed to deal with the complex deformation behavior characteristics based on the experimental data. The performance of ANN model has been evaluated in terms of correlation coefficient (R) and average absolute relative error (AARE). A comparative study on Arrhenius-type constitutive equation and ANN model for as-extruded 7075 aluminum alloy was conducted. Finally, the ANN model was successfully applied to the development of processing map and implanted into finite element simulation. The results have sufficiently articulated that the well-trained ANN model with BP algorithm has excellent capability to deal with the complex flow behaviors of as-extruded 7075 aluminum alloy and has great application potentiality in hot deformation processes.

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.

Constitutive Analysis of Ni-Base Superalloy Hastelloy X under Hot Compression Based on Thermodynamics

2012 ◽  
Vol 252 ◽  
pp. 73-76
Author(s):  
Horng Yu Wu ◽  
Hsu Cheng Liu ◽  
Feng Jun Zhu ◽  
Chui Hung Chiu
Keyword(s):  
Flow Stress ◽  
Constitutive Equation ◽  
Strain Rate ◽  
Hot Deformation ◽  
Elevated Temperatures ◽  
Flow Behavior ◽  
Dislocation Creep ◽  
Hastelloy X ◽  
Constitutive Analysis ◽  
Base Superalloy

Hot deformation characteristics of Hastelloy X Ni-base superalloy were investigated at elevated temperatures. Hot compressive tests were carried out in the temperature and strain rate ranges from 900 to 1150 °C and 0.001 to 1 s–1, respectively. The constitutive equation relating flow stress, temperature, and strain rate was obtained based on the peak stresses. The flow behavior showed that the softening mechanisms were related to the dynamic recovery (DRV) and dynamic recrystallization (DRX). The flow stress of Hastelloy X was fitted well by the constitutive equation of the hyperbolic sine function. The constitutive analysis suggested that the hot deformation mechanism of the Hastelloy X was dislocation creep.

scholarly journals Characterization of Hot Deformation Behavior and Processing Maps of Mg-3Sn-2Al-1Zn-5Li Magnesium Alloy

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1262 ◽  
Author(s):  
Yuhang Guo ◽  
Yaodong Xuanyuan ◽  
Chunnan Lia ◽  
Sen Yang
Keyword(s):  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Processing Maps ◽  
Compression Tests ◽  
Softening Mechanism ◽  
Signal Peak ◽  
The Operating Mechanism ◽  
The Stability

The dynamic microstructure evolution of Mg-3Sn-2Al-1Zn-5Li magnesium alloy during hot deformation is studied by hot compression tests over the temperature range of 200–350 °C under the strain rate of 0.001–1 s−1, whereafter constitutive equations and processing maps are developed and constructed. In most of cases, the material shows typical dynamic recrystallization (DRX) features, with a signal peak value followed by a gradual decrease. The value of Q (deformation activation energy) is 138.89414 kJ/mol, and the instability domains occur at high strain rate but the stability domains are opposite, and the optimum hot working parameter for the studied alloy is determined to be 350 °C/0.001 s−1 according to the processing maps. Within 200–350 °C, the operating mechanism of dynamic recrystallization (DRX) of Mg-3Sn-2Al-1Zn-5Li alloy during hot deformation is mainly affected by strain rate. Dynamic recrystallization (DRX) structures are observed from the samples at 300 °C/0.001 s−1 and 350 °C/0.001 s−1, which consist of continuous DRX (CDRX) and discontinuous DRX (DDRX). However, dynamic recovery (DRV) still dominates the softening mechanism. At the grain boundaries, mass dislocation pile-ups and dislocation tangle provide sites for potential nucleation. Meanwhile, flow localization bands are observed from the samples at 200 °C/1 s−1 and 250 °C/0.1 s−1 as the main instability mechanism.

HOT DEFORMATION BEHAVIOR OF IN SITUTIB2 REINFORCED 6351 AL COMPOSITES DURING COMPRESSION AT ELEVATED TEMPERATURES

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1432-1437
Author(s):  
SHENGLI GUO ◽  
DEFU LI ◽  
DONG CHEN ◽  
HAOWEI WANG
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Elevated Temperatures ◽  
Dynamic Recovery ◽  
Matrix Alloy ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Mixed Salt ◽  
Increasing Temperature

The hot deformation behavior of in situ TiB 2 reinforced 6351 Al composites synthesized by mixed salt reaction method was investigated by compression tests in the temperature range of 300-550°C and strain rate range of 0.001-10 s-1. The microstructure evolution during compression was observed by employing transmission electron microscopy (TEM). The results show that, the flow stress decreases with decreasing strain rate and increasing temperature, and the activation energy is about 169.98 kJ/mol. Microstructure observation indicates that the complex dislocation structures were formed around the TiB 2 particulate at the lower temperature and the lower strain rate and their density is reducing with increasing temperature. Dynamic recovery and recrystalized structures were observed in the lower and higher deformation temperature, respectively. At the higher strain rate, the interface separation between TiB 2 particulate and Al matrix alloy and TiB 2 particulate cracking were found in this study. The main restoration mechanisms of TiB 2/6351 composites during hot deformation are dynamic recovery and dynamic recrystallization.

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