scholarly journals Hot deformation behavior of 60NiTi shape-memory alloy fabricated by hot isostatic pressing

2022 ◽  
Author(s):  
Mei-ling Li ◽  
Wen-jin Gao ◽  
Ying-hao Zhou
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Work Hardening ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Dynamic Equilibrium ◽  
High Stress ◽  
Cylindrical Sample ◽  
Hot Working ◽  
Hot Deformation Behavior

Abstract The 60NiTi (Ni60wt%–Ti40wt%) intermetallic is a hard-to-process material. Understanding of hot deformation behavior is crucial for the hot working of 60NiTi. This work studied hot deformation behavior and corresponding microstructure of the hot isostatic pressed 60NiTi in the temperature range of 900 °C–1050 °C and at strain rates of 0.1, 0.01, and 0.001 s-1 through a hot compression test. The flow stress and microstructure were susceptible to the hot deformation parameters. The flow stress decreased with the increase in deformation temperature and decrease in strain rate. Work hardening occurred at a small strain, then followed by softening; finally, near-dynamic equilibrium was achieved between work hardening and softening. A constitutive equation was developed to describe the effects of strain rate and temperature on flow stress. Simulation of hot deformation via the finite element method revealed the workpiece’s inhomogeneous deformation. The deformation occurred mainly in the center area of the cylindrical sample, resulting in high stress and strain concentrations in this region and causing the equiaxial grains to be compressed into prolate grains. This work can provide guidance for the hot working, such as forging and hot rolling, of 60NiTi.

Hot Deformation Behavior and Microstructure of U720Li Alloy

2013 ◽  
Vol 709 ◽  
pp. 143-147 ◽  
Author(s):  
Tao Wang ◽  
Zhao Li ◽  
Shu Hong Fu ◽  
Yong Zhang ◽  
Yu Xin Zhao ◽  
...  
Keyword(s):  
Grain Size ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Primary Phase ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Fine Grain ◽  
Lower Strain

The hot deformation behavior of U720Li was investigated by isothermal compression tests at temperature ranging from 1060-1180°C and strain rate from 0.001s-1 to 20s-1. The flow stress-strain curves and microstructures were investigated and a constitutive equation was established. It is found that flow stress is sensitive to stain rate and deformation temperature greatly. The higher stain rate resultes in a larger fluctuation in flow stress. The hot deformation activation energy is determined to be 552.8kJ/mol. Grain size increases with increasing temperature and decreases firstly and then increases with increasing strain rate. U720Li alloy should be deformed below the solve temperature of γ primary phase with lower strain rate in order to obtain the even and fine grain size.

scholarly journals Hot deformation behavior of TC18 titanium alloy

2013 ◽  
Vol 17 (5) ◽  
pp. 1523-1528
Author(s):  
Bao-Hua Jia ◽  
Wei-Dong Song ◽  
Hui-Ping Tang ◽  
Jian-Guo Ning
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
True Strain ◽  
Testing Machine ◽  
Constitutive Relationship ◽  
Compression Tests ◽  
Hot Deformation Behavior

Isothermal compression tests of TC18 titanium alloy at the deformation temperatures ranging from 25?C to 800?C and strain rate ranging from 10-4 to 10-2 s-1 were conducted by using a WDW-300 electronic universal testing machine. The hot deformation behavior of TC18 was characterized based on an analysis of the true stress-true strain curves of TC18 titanium alloy. The curves show that the flow stress increases with increasing the strain rate and decreases with increasing the temperature, and the strain rate play an important role in the flow stress when increasing the temperatures. By taking the effect of strain into account, an improved constitutive relationship was proposed based on the Arrhenius equation. By comparison with the experimental results, the model prediction agreed well with the experimental data, which demonstrated the established constitutive relationship was reliable and can be used to predict the hot deformation behavior of TC18 titanium alloy.

Modeling the Hot Deformation Behavior of 1565ch Aluminum Alloy

2016 ◽  
Vol 684 ◽  
pp. 35-41 ◽  
Author(s):  
S.V. Rushchits ◽  
E.V. Aryshensky ◽  
S.M. Sosedkov ◽  
A.M. Akhmed'yanov
Keyword(s):  
Aluminum Alloy ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Static Recrystallization ◽  
Strain Rates ◽  
Strain Resistance ◽  
Hot Deformation Behavior ◽  
Zirconium Addition

The deformation behavior of 1565ch alloy under the plane-strain conditions in the temperature range of 350–490 оС and strain rates range of 0,1–10 s-1 is studied. The expression for steady flow stress as the functions of temperature of deformation and strain rate is obtained. It is established that 1565ch alloy with zirconium addition shows higher strain resistance and less tendency to dynamic and static recrystallization than AMg6.

Artificial Neural Network to Predict the Hot Deformation Behavior of Super 13Cr Martensitic Stainless Steel

2011 ◽  
Vol 695 ◽  
pp. 361-364 ◽  
Author(s):  
Ying Han ◽  
Guan Jun Qiao ◽  
Dong Na Yan ◽  
De Ning Zou
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Stainless Steel ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Martensitic Stainless Steel ◽  
Ann Model ◽  
Hot Deformation Behavior

The hot deformation behavior of super 13Cr martensitic stainless steel was investigated using artificial neural network (ANN). Hot compression tests were carried out at the temperature range of 950°C to 1200°C and strain rate range of 0.1–50s–1at an interval of an order of magnitude. Based on the limited experimental data, the ANN model for the constitutive relationship existed between flow stress and strain, strain rate and deformation temperature was developed by back-propagation (BP) neural network method. A three layer structured network with one hidden layer and ten hidden neurons was trained and the normalization method was employed in training for avoiding over fitting. Modeling results show that the developed ANN model can efficiently predict the flow stress of the steel and reflect the hot deformation behavior in the whole deforming process.

Characterization of Hot Deformation Behavior of Ti-4.5Al-3V-2Mo-2Fe Titanium Alloy

2016 ◽  
Vol 849 ◽  
pp. 309-316 ◽  
Author(s):  
Li Wei Zhu ◽  
Xin Nan Wang ◽  
Yue Fei ◽  
Jing Li ◽  
Zhi Shou Zhu
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Constant Strain Rate ◽  
Test Machine ◽  
Peak Efficiency ◽  
Hot Deformation Behavior ◽  
Dynamic Materials

The hot deformation behavior of Ti-4.5Al-3V-2Mo-2Fe (SP-700) titanium alloy in the temperature range of 650°C~950°C and constant strain rate of 0.01, 0.1, 1 and 10s-1 has been investigated by hot compressive testing on the Gleeble-1500D thermal simulation test machine. The experimental results indicated that the hot deformation behavior of SP-700 alloy was sensitive to the deformation temperature and strain rate. The peak flow stress decreased with the increase of temperature and the decrease of strain rate. The flow curves characteristic under different deformation parameters show significant different. Analysis of the flow stress dependence on strain rate and temperature gives a stress exponent of n as 4.8235 and a deformation activation energy of Q as 410kJ/mol. Based on the dynamic materials model, the processing map is generated, which shows that the most peak efficiency domain appears at the temperature of 725°C~775°C and the strain rate of 0.001 s-1~0.003s-1 with a peak efficiency of 45% at about 750°C/0.01s-1.

scholarly journals Hot Deformation Behavior and Constitutive Analysis of As-Extruded Mg–6Zn–5Ca–3Ce Alloy Fabricated by Rapid Solidification

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 480
Author(s):  
Chengli Bao ◽  
Tao Zhou ◽  
Laixin Shi ◽  
Mingao Li ◽  
Li Hu ◽  
...  
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Rapid Solidification ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Dislocation Motion ◽  
Hot Deformation Behavior ◽  
Constitutive Analysis ◽  
Fine Grain ◽  
Hcp Structure

The plasticity of Mg–6Zn–5Ca–3Ce alloy fabricated by rapid solidification (RS) at room temperature is poor due to its hexagonal-close-packed (HCP) structure. Therefore, hot deformation of RS Mg–6Zn–5Ca–3Ce alloy at elevated temperature would be a major benefit for manufacturing products with complex shapes. In the present study, hot deformation behavior of as-extruded Mg–6Zn–5Ca–3Ce alloy fabricated by RS was investigated by an isothermal compression test at a temperature (T) of 573–673 K and strain rate (ε˙) of 0.0001–0.01 s−1. Results indicated that the flow stress increases along with the declining temperature and the rising strain rate. The flow stress behavior was then depicted by the hyperbolic sine constitutive equation where the value of activation energy (Q) was calculated to be 186.3 kJ/mol. This issue is mainly attributed to the existence of fine grain and numerous second phases, such as Mg2Ca and Mg–Zn–Ce phase (T’ phase), acting as barriers to restrict dislocation motion effectively. Furthermore, strain compensation was introduced to incorporate the effect of plastic strain on material constants (α,Q,n,lnA) and the predicted flow stresses under various conditions were roughly consistent with the experimental results. Moreover, the processing maps based on the Murty criterion were constructed and visualized to find out the optimal deformation conditions during hot working. The preferential hot deformation windows were identified as follows: T = 590–640 K, ε˙ = 0.0001–0.0003 s−1 and T = 650–670 K, ε˙ = 0.0003–0.004 s−1 for the studied material.

Hot deformation behavior and dynamic recrystallization constitutive modeling of Al–Cu–Mg powder compacts processed by extrusion at elevated temperatures

2020 ◽  
pp. 146442072097132
Author(s):  
Katti Bharath ◽  
Asit Kumar Khanra ◽  
MJ Davidson
Keyword(s):  
Powder Metallurgy ◽  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Relative Density ◽  
Constitutive Equations ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Peak Flow ◽  
Hot Deformation Behavior

The deformation behavior of Al–Cu–Mg sintered preforms has been investigated by extrusion in the temperature range of 450–550°C and strain rate range of 0.1–0.3 s−1, respectively. The aim of this study is to analyze the effect of initial preform relative density on the hot deformation behavior and to model and predict the flow stress of extruded samples using constitutive equations. The true stress–strain curves exhibit three stages of deformation, which represent work hardening, dynamic recovery, and dynamic recrystallization during deformation at different temperatures, strain rates, and initial preform relative densities of 70%, 80%, and 90%, respectively. The results show that the flow stress values are influenced by initial preform relative density, deformation temperature, and strain rate. Microstructural examination of extruded specimens has been performed by optical microscopy and scanning electron microscopy. Arrhenius-type constitutive equations are developed to predict the flow stress of hot-extruded powder metallurgy processed aluminum alloy (Al–4%Cu–0.5%Mg). Zener–Hollomon parameter is used to explain the relationship between peak flow stress, temperature, and strain rate in an exponential equation containing the deformation activation energy and material constants. Subsequently, the statistical indicators correlation coefficient ( R) and the average absolute relative error are assessed to confirm the validity of constitutive equations. The results indicate the experimental and predicted peak flow stress values are in good agreement, which indicate the accuracy and reliability of the developed model for powder metallurgy processed Al–4%Cu–0.5%Mg preforms.

scholarly journals Hot Deformation Behavior and Microstructural Evolution of PM Ti43Al9V0.3Y with Fine Equiaxed γ and B2 Grain Microstructure

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 896
Author(s):  
Dongdong Zhang ◽  
Yuyong Chen ◽  
Guoqing Zhang ◽  
Na Liu ◽  
Fantao Kong ◽  
...  
Keyword(s):  
Strain Rate ◽  
Microstructure Evolution ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Hot Working ◽  
Boundary Slip ◽  
Hot Deformation Behavior ◽  
Strain And Strain Rate ◽  
Working Parameters ◽  
Temperature Strain

The hot deformation behavior and microstructure evolution of powder metallurgy (PM) Ti43Al9V0.3Y alloy with fine equiaxed γ and B2 grains were investigated using uniaxial hot compression. Its stress exponent and activation energy were 2.78 and 295.86 kJ/mol, respectively. The efficiency of power dissipation and instability parameters were evaluated, and processing maps at 50% and 80% strains were developed. It is demonstrated that the microstructure evolution was dependent on the temperature, strain, and strain rate. Both temperature and strain increases led to a decrease in the γ phase. Moreover, dynamic recrystallization (DRX) and grain boundary slip both played important roles in deformation. Reasonable parameters for secondary hot working included temperatures above 1100 °C but below 1200 °C with a strain rate of less than 1 s−1 at 80% strain. Suitable hot working parameters at 50% strain were 1150–1200 °C/≤1 s−1 and 1000–1200 °C/≤0.05 s−1.

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 Hot Deformation Behavior and Microstructure Evolution of a TiBw/Near α-Ti Composite with Fine Matrix Microstructure

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 481 ◽  
Author(s):  
Zhang ◽  
Lian ◽  
Chen ◽  
Sun ◽  
Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Microstructure Evolution ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Matrix Microstructure

The hot deformation behavior and microstructure evolution of a 7.5 vol% TiBw/near α-Ti composite with fine matrix microstructure were investigated under the deformation conditions in a temperature range of 800–950 °C and strain rate range of 0.001–1 s−1 using plane strain compression tests. The flow stress curves show different characteristics according to the various deformation conditions. At a higher strain rate (1 s−1), the flow stress of the composite continuously increases until a peak value is reached. The activation energy is 410.40 kJ/mol, much lower than the activation energy of as-sintered or as-forged composites. The decreased activation energy is ascribed to the breaking of the TiBw reinforcement during the multi-directional forging and the resultant fine matrix microstructure. Refined reinforcement and refined matrix microstructure significantly improve the hot deformation ability of the composite. The deformation conditions determine the morphology and fraction of α and β phases. At 800–900 °C and 0.01 s−1 the matrix α grains are much refined due to the continuous dynamic recrystallization (CDRX). The processing map is constructed based on the hot deformation behavior and microstructure evolution. The optimal hot processing window is determined to be 800–950 °C/0.001–0.01 s−1, which lead to CDRX of primary α grains or dynamic recovery (DRV) and dynamic recrystallization (DRX) of β phase.

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