scholarly journals Study on the Evolution of Damage Degradation at Different Temperatures and Strain Rates for Ti-6Al-4V Alloy

2019 ◽  
Vol 38 (2019) ◽  
pp. 332-341
Author(s):  
Lin Gao ◽  
Jiang Zhao ◽  
Guo-zheng Quan ◽  
Wei Xiong ◽  
Chao An
Keyword(s):  
Strain Rate ◽  
Ductile Fracture ◽  
Element Model ◽  
Processing Parameters ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Different Temperatures ◽  
Strain Stress ◽  
Effects Of Temperature ◽  
The Finite Element Model

AbstractIt is a significant issue to deeply understand the nature relationships between damage degradation and deforming parameters, and then identify the changes of initial ductile fracture time with processing parameters and further adjusting the forming processes for obtaining the fracture-free components. For Ti-6Al-4V alloy, the strain-stress data in the temperature range of 1023–1323 K and strain rate range of 0.01–10 s−1 were obtained by compression tests. The finite element model with stress-strain data was constructed to simulate the ductile damage cumulating processes under different conditions and obtained the maximum damage values. Subsequently, the ductile fracture criterion (DFC) of Ti-6Al-4V alloy was established and the effects of temperature and strain rate on DFC were discussed. The results show that the variation range of DFC under different deformation conditions is 0.07–0.15. Subsequently, the deformation conditions with higher fracture risk were identified as 1200∼1275 K & 1∼10 s−1 and verified with the experiment observations.

Modeling of the Hot Flow Behaviors for Ti-6Al-4V-0.1Ru Alloy by GA-BPNN Model and Its Application

2018 ◽  
Vol 37 (6) ◽  
pp. 551-562 ◽  
Author(s):  
Yu-ting Zhou ◽  
Yu-feng Xia ◽  
Lai Jiang ◽  
Shuai Long ◽  
Dong Yang
Keyword(s):  
Strain Rate ◽  
Back Propagation ◽  
Interaction Space ◽  
Processing Parameters ◽  
Back Propagation Neural Network ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Strain And Strain Rate ◽  
Deformation Behaviors ◽  
Bpnn Model

AbstractA series of compression tests were performed on Ti-6Al-4V-0.1Ru titanium alloy in nine temperatures between 750 and 1150 °C and a strain rate range of 0.01 to 10s−1. The hot deformation behaviors of Ti-6Al-4V-0.1Ru showed highly non-linear intrinsic relationships with temperature, strain and strain rate. The flow curves exhibited different softening mechanisms, dynamic recrystallization (DRX) and dynamic recovery (DRV). In this study, the rheological behaviors of Ti-6Al-4V-0.1Ru were modeled using a special hybrid prediction model, where genetic algorithm (GA) was implemented to do a back-propagation neural network (BPNN) weights optimization, namely GA-BPNN. Subsequently, the predicted results were compared with experimental values and GA-BPNN model showed the ability to predict the flow behaviors of Ti-6Al-4V-0.1Ru with superior accuracy. Then a 3-D continuous interaction space was constructed to visually reveal the successive relationships among processing parameters. Finally, the predicted data were applied to process simulation and accuracy results were achieved.

scholarly journals Evaluation of Varying Ductile Fracture Criteria for 42CrMo Steel by Compressions at Different Temperatures and Strain Rates

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Guo-zheng Quan ◽  
Gui-chang Luo ◽  
An Mao ◽  
Jian-ting Liang ◽  
Dong-sen Wu
Keyword(s):  
Strain Rate ◽  
Ductile Fracture ◽  
Ductile Damage ◽  
Compression Tests ◽  
Fracture Criteria ◽  
Ductile Fracture Criteria ◽  
Bulk Forming ◽  
42Crmo Steel ◽  
Different Temperatures ◽  
Tension Testing

Fracturing by ductile damage occurs quite naturally in metal forming processes, and ductile fracture of strain-softening alloy, here 42CrMo steel, cannot be evaluated through simple procedures such as tension testing. Under these circumstances, it is very significant and economical to find a way to evaluate the ductile fracture criteria (DFC) and identify the relationships between damage evolution and deformation conditions. Under the guidance of the Cockcroft-Latham fracture criteria, an innovative approach involving hot compression tests, numerical simulations, and mathematic computations provides mutual support to evaluate ductile damage cumulating process and DFC diagram along with deformation conditions, which has not been expounded by Cockcroft and Latham. The results show that the maximum damage value appears in the region of upsetting drum, while the minimal value appears in the middle region. Furthermore, DFC of 42CrMo steel at temperature range of 1123~1348 K and strain rate of 0.01~10 s-1are not constant but change in a range of 0.160~0.226; thus, they have been defined as varying ductile fracture criteria (VDFC) and characterized by a function of temperature and strain rate. In bulk forming operations, VDFC help technicians to choose suitable process parameters and avoid the occurrence of fracture.

Critical Strain for the Initiation of Dynamic Recrystallization in a Ni-Fe Base Alloy

2004 ◽  
Vol 449-452 ◽  
pp. 577-580
Author(s):  
Young Sang Na ◽  
Young Mok Rhyim ◽  
J.Y. Lee ◽  
Jae Ho Lee
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Critical Strain ◽  
Base Alloy ◽  
Strain Rate Range ◽  
Boundary Phase ◽  
Alloy 718 ◽  
Compression Tests ◽  
Temperature Range ◽  
Critical Strains

In order to quantitatively analyze the critical strain for the initiation of dynamic recrystallization in Ni-Fe-based Alloy 718, a series of uniaxial compression tests was conducted in the temperature range 927°C - 1066°C and the strain rate range 5 x 10-4s-1- 5 s-1with varying initial grain size. The critical strains were graphically determined based on one parameter approach and microscopically confirmed. The effect of γ'' (matrix-hardening phase) and δ (grain boundary phase)on the critical strain was simply discussed. The constitutive model for the critical strain of Alloy 718 was constructed using the experimental data obtained from the higher strain rate and the temperature range between 940°C and 1040°C.

Strain Rate Sensitivity of Ultrafine-Grained CP-Ti Processed by ECAP at Room Temperature

2010 ◽  
Vol 667-669 ◽  
pp. 707-712 ◽  
Author(s):  
Xiao Yan Liu ◽  
Xi Cheng Zhao ◽  
Xi Rong Yang
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Ultrafine Grained ◽  
Die Set ◽  
Increasing Temperature ◽  
Cp Ti

Ultrafine-grained (UFG) commercially pure (CP) Ti with a grain size of about 200 nm was produced by ECAP up to 8 passes using route BC at room temperature. For ECAP processing a proper die set was designed and constructed with an internal channel angle Φ of 120° and an outer arc of curvature Ψ of 20°. Strain rate sensitivity of UFG CP-Ti and CG CP-Ti were investigated by compression tests in the temperature range of 298~673K and strain rate range of 10-4~100s-1 using Gleeble simulator machine. Evolution of the microstructure during compression testing was observed using optical microscopy (OM) and transmission electron microscopy (TEM). Strain rate sensitivity value m of the UFG CP-Ti has been measured and is found to increase with increasing temperature and decreasing strain rate, and is enhanced compared to that of CG CP-Ti. Result of the deformation activation energy determination of UFG CP-Ti indicates that the deformation mechanism in UFG CP-Ti is correlated to the grain boundaries.

Characterization of Hot Deformation Behavior of Udimet720Li Superalloy Using Processing Map

2014 ◽  
Vol 887-888 ◽  
pp. 1161-1168
Author(s):  
Jian Guo Wang ◽  
Dong Liu ◽  
Tao Wang ◽  
Yan Hui Yang
Keyword(s):  
Strain Rate ◽  
Deformation Behavior ◽  
High Strain ◽  
Flow Behavior ◽  
Strain Range ◽  
Peak Stress ◽  
Strain Rate Range ◽  
Hot Working ◽  
Compression Tests ◽  
Hollomon Parameter

The deformation behavior of a Udimet720Li superalloy under hot compression tests was characterized in the temperature range of 1060~1160°C and strain rate range of 0.001~20s-1. Processing maps were conducted at a series of strains to calculate the efficiency of hot working and to recognize the instability regions of the flow behavior. A Zener-Hollomon parameter is given to characterize the dependence of peak stress on temperature and strain rate. The efficiency of power dissipation of the Udimet720Li superalloy obtained in a strain range of 0.1~0.7 are essentially similar, which indicates that strain does not have a significant influence and the instability region shown in high strain and high strain rates at all temperatures. The regions for the full recrystallization can be divided by the dissolution beginning temperature of primary γ'which are the optimum hot working parameters.

Performance assessment of rigid polyurethane foam core sandwich panels under blast loading

2019 ◽  
Vol 11 (1) ◽  
pp. 109-130 ◽  
Author(s):  
Hosein Andami ◽  
Hamid Toopchi-Nezhad
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Polyurethane Foam ◽  
Sandwich Panel ◽  
Sandwich Panels ◽  
Element Model ◽  
Polyurethane Foams ◽  
Compression Tests ◽  
Foam Layer ◽  
The Finite Element Model

The performance of rigid polyurethane foams, as an energy absorbent core of sandwich panels covered with two exterior steel sheets, was investigated numerically through finite element methods. After verifying the finite element model, numerical studies were conducted to investigate the role of thickness and density of the foam layer in the response behavior of sandwich panels under blast loads. A set of cylindrical polyurethane foam specimens were manufactured at five different nominal densities, 90, 140, 175, 220, and 250 kg/m3, and their stress–strain curves were evaluated using uniaxial compression tests. The test data were then employed to define characteristics of the polyurethane foams in the finite element model. Based on the results of finite element analysis runs, the optimum density of the foam layer was determined by assessing two response parameters including the peak pressure transmitted to the back face of the foam layer and the maximum deflection of sandwich panel. These response parameters were found to be affected differently by variations in the density of the foam layer within the panel. An increase in the thickness of the foam layer, to a certain extent, was found to be beneficial to the mitigation capability of sandwich panel.

Texture Changes during Uniaxial Compression of Mg-3Al-1Zn

2004 ◽  
Vol 467-470 ◽  
pp. 429-434 ◽  
Author(s):  
Petra Backx ◽  
Matthew R. Barnett ◽  
Leo Kestens
Keyword(s):  
Uniaxial Compression ◽  
Annealing Treatment ◽  
Processing Parameters ◽  
Mechanical Anisotropy ◽  
Uniaxial Compression Test ◽  
Compression Tests ◽  
Texture Change ◽  
Different Temperatures ◽  
Axis Compression ◽  
Different Strains

The mechanical anisotropy of wrought Mg alloys is very high. For example the yield stress of extruded Mg-3Al-1Zn tested in tension can be as high as twice that obtained in compression [1]. To solve the problems this creates for product design it is necessary to understand the sensitivity of texture to processing parameters. Uniaxial compression tests at different temperatures were performed on cylindrical samples of an extruded Mg-3Al-1Zn bar. The texture during this deformation changes from a situation where all crystal c-axes are nearly perpendicular to the sample axis to one where the c-axes are all nearly parallel to this axis. Compression was stopped at different strains to examine the rate of this texture change. Textures were examined using EBSD measurements. It was found that different mechanisms operate depending on the temperature of deformation and that a variety of textures can be created. Also it was seen that an annealing treatment performed after compression has an influence on the texture. Afterwards the samples were subjected to another uniaxial compression test to examine the influence of texture on room temperature properties.

Thermal Response Analysis and FE Modeling of Weapon

2012 ◽  
Vol 503-504 ◽  
pp. 11-14
Author(s):  
Yan Jun Zhao ◽  
Xin Jun Li ◽  
Yong Hai Wu ◽  
Cheng Xu
Keyword(s):  
Thermal Analysis ◽  
Finite Element ◽  
Temperature Field ◽  
Research Work ◽  
Thermal Response ◽  
Element Model ◽  
Response Analysis ◽  
Fe Modeling ◽  
Effects Of Temperature ◽  
The Finite Element Model

Thermal is a important factor that affect weapon firing accuracy and security in the process of weapon fire, so thermal analysis of weapon has important meaning . Aim at researched Weapon, the finite element model of the gun body was built, the temperature field of the gun body was calculated by FEM. The effects of temperature of the gun body on firer and aiming mechanism were also studied. Current research work will be helpful the weapon design

Effect of Severe Caliber Rolling on Superplastic Properties of Mg-3Al-1Zn (AZ31) Alloy

2012 ◽  
Vol 735 ◽  
pp. 327-331 ◽  
Author(s):  
Rajendra Doiphode ◽  
Rahul Ramesh Kulkarni ◽  
S.V.S. Narayana Murty ◽  
Nityanand Prabhu ◽  
Bhagwati Prasad Kashyap
Keyword(s):  
Strain Rate ◽  
Constant Strain Rate ◽  
Material Constant ◽  
Az31 Alloy ◽  
Strain Rate Range ◽  
Constitutive Relationship ◽  
Grain Sizes ◽  
Different Temperatures ◽  
Rate Test ◽  
Superplastic Properties

Fine grains were developed in Mg-3Al-1Zn (AZ31) alloy by isothermal caliber rolling at five different temperatures in the range of 250-450°C. The samples of different grain sizes were deformed by constant strain rate and differential strain rate test techniques over the temperature range of 220-450 °C and strain rate range of 10-5 to 10-1 s-1. The effects of grain size, test temperature and strain rate on flow stSuperscSuperscript textript textress were analysed to develop the constitutive relationship for supSuperscript texterplastic deformation. The parameters of the constitutive relationship obtained from the constant strain rate tests and differential strain rate tests were used to find out the material constant A of the constitutive relationship.

Hot Deformation Behavior and Microstructural Evolution of Mg-Nd-Zn-Zr Magnesium Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 320-326 ◽  
Author(s):  
Wen Xiang Wu ◽  
Li Jin ◽  
Jie Dong ◽  
Zhen Yan Zhang ◽  
Wen Jiang Ding
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Microstructural Evolution ◽  
Hot Deformation ◽  
Fine Particles ◽  
Volume Fraction ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Average Size

The hot deformation behaviors and microstructural evolution of Mg-3.0Nd-0.2Zn-0.4Zr (wt. %, NZ30K) alloy were investigated by means of the isothermal hot compression tests at temperatures of 350-500 °C with strain rates of 0.001, 0.01, 0.1 and 1s-1. The results showed that the flow stress increased to a peak and then decreased which showed a dynamic flow softening. The flow stress behavior was described by the hyperbolic sine constitutive equation with an average activation energy of 193.8 kJ/mol. The average size of dynamically recrystallized grains of hot deformed NZ30K alloy was reduced by increasing the strain rate and/or decreasing the deformation temperature. A large amount of fine particles precipitated in the grains interior and at the grain boundaries when heated to the compression temperatures and soaked for 5min below 450 °C. However, the volume fraction of particles decreased significantly when soaked for 5 min at 500 °C, and the coarse particles precipitated mainly at the grain boundaries. Hot deformation at the temperature of 500 °C around and at the strain rate range of 0.1s-1 was desirable for NZ30K alloy.

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