A Constitutive Equation Coupling the Grain Size during the High Temperature Deformation of Ti-6.62Al-5.14Sn-1.82Zr Alloy

2007 ◽  
Vol 561-565 ◽  
pp. 155-158 ◽  
Author(s):  
Jiao Luo ◽  
Miao Quan Li ◽  
Y.Q. Hu
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Flow Stress ◽  
Constitutive Equation ◽  
Steady Flow ◽  
Maximum Error ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Stress Model ◽  
Flow Stress Model

A constitutive equation has been established to describe the effect of grain size on the deformation behavior of Ti-6.62Al-5.14Sn-1.82Zr alloy during the high temperature. In this paper, firstly a steady flow stress model is proposed, and a function relating to the grain size is introduced to modify the steady flow stress model. Meanwhile, a microstructure model established by the fuzzy neural network method is applied to calculate the grain size of prior α phase during the high temperature deformation of Ti-6.62Al-5.14Sn-1.82Zr alloy. The calculated flow stress using the present constitutive equation shows a good agreement with the experimental flow stress of the Ti-6.62Al-5.14Sn-1.82Zr alloy. The relative maximum error was not more than 15%.

High Temperature Deformation Behavior of Ti-7333 Titanium Alloy and its Flow Stress Model

2012 ◽  
Vol 538-541 ◽  
pp. 945-950 ◽  
Author(s):  
Jiang Kun Fan ◽  
Hong Chao Kou ◽  
Min Jie Lai ◽  
Bin Tang ◽  
Hui Chang ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Flow Stress ◽  
Strain Rate ◽  
Deformation Behavior ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Stress Model ◽  
Compression Tests ◽  
Flow Stress Model

The effects of processing parameters on deformation behavior of a new near β titanium alloy were investigated by using compression tests. The experiments were carried out in the Gleeble-3800 thermal and mechanical simulator in the temperature range of 770-970°C and strain rate range of 10-3-10s-1, and height direction reduction of 70%. The results show that the flow stress of Ti-7333 titanium alloy increases obviously with the strain and reaches a peak, then decreases to a steady value. The steady and peak stress significantly decreases with the increase of deformation temperature and decrease of strain rate. The flow stress model of Ti-7333 titanium alloy during high temperature deformation was established by using the regression method. The average relative difference between the calculated and experimental flow stress is 6.33%. The flow stress model can efficiently predict the deformation behavior of Ti-7333 titanium alloy during high temperature deformation.

Characterization of High Temperature Deformation Behavior of BFe10-1-2 Cupronickel Alloy Using Orthogonal Analysis

2017 ◽  
Vol 36 (7) ◽  
pp. 701-710
Author(s):  
Jun Cai ◽  
Kuaishe Wang ◽  
Xiaolu Zhang ◽  
Wen Wang
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Constitutive Equation ◽  
Strain Rate ◽  
Deformation Behavior ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Compression Tests ◽  
Statistical Parameters ◽  
Orthogonal Analysis

AbstractHigh temperature deformation behavior of BFe10-1-2 cupronickel alloy was investigated by means of isothermal compression tests in the temperature range of 1,023~1,273 K and strain rate range of 0.001~10 s–1. Based on orthogonal experiment and variance analysis, the significance of the effects of strain, strain rate and deformation temperature on the flow stress was evaluated. Thereafter, a constitutive equation was developed on the basis of the orthogonal analysis conclusions. Subsequently, standard statistical parameters were introduced to verify the validity of developed constitutive equation. The results indicated that the predicted flow stress values from the constitutive equation could track the experimental data of BFe10-1-2 cupronickel alloy under most deformation conditions.

scholarly journals Effect of Annealing on Structure and Mechanical Behavior of an AA2139 Alloy

2014 ◽  
Vol 783-786 ◽  
pp. 258-263 ◽  
Author(s):  
Damir Tagirov ◽  
Daria Zhemchuzhnikova ◽  
Marat Gazizov ◽  
Rustam Kaibyshev
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Flow Stress ◽  
Room Temperature ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Aged Alloy ◽  
Coarse Particles ◽  
Initial Material ◽  
High Ductility

An AA2139 alloy with a chemical composition of Al–4.35Cu-0.46%Mg–0.63Ag-0.36Mn–0.12Ti (in wt.%) and an initial grain size of about 155 μm was subjected to annealing at 430°C for 3 h followed by furnace cooling. This treatment resulted in the formation of a dispersion of coarse particles having essentially plate-like shape. The over-aged alloy exhibits lower flow stress and high ductility in comparison with initial material in the temperature interval 20-450°C. Examination of microstructural evolution during high-temperature deformation showed localization of plastic flow in vicinity of coarse particles. Over-aging leads to transition from ductile-brittle fracture to ductile and very homogeneous ductile fracture at room temperature.

A Multi-Scale Constitutive Model in High Temperature Deformation of Near Alpha Ti-5.6Al-4.8Sn-2.0Zr Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 1598-1601 ◽  
Author(s):  
Miao Quan Li ◽  
Jiao Luo
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Flow Stress ◽  
Constitutive Model ◽  
Deformation Behavior ◽  
Volume Fraction ◽  
Optimization Technique ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Multi Scale

Isothermal compression of near alpha Ti-5.6Al-4.8Sn-2.0Zr alloy is conducted on a Thermecmaster-Z simulator at the deformation temperatures ranging from 1173 K to 1333 K, the strain rates ranging from 0.001 s-1 to 10.0 s-1 at an interval of an order magnitude and the height reductions ranging from 50% to 70%. The primary grain size is measured at an OLYMPUS PMG3 microscope with the quantitative metallography SISC IAS V8.0 image analysis software. A multi-scale constitutive model coupling the grain size, volume fraction and dislocation density is established to represent the deformation behavior of near alpha Ti-5.6Al-4.8Sn-2.0Zr alloy in high temperature deformation, in which the flow stress is decomposed a thermal stress and an athermal stress. A Kock-Mecking model is adopted to describe the thermally activated stress, and an athermal stress model accounts for the working hardening and Hall-Petch effect. A genetic algorithm (GA)-based objective optimization technique is used for determining material constants in this study. The mean relative difference between the predicted and experimental flow stress is 5.98%, thus it can be concluded that the multi-scale constitutive model with high prediction precision can efficiently predict the deformation behavior of near alpha Ti-5.6Al-4.8Sn-2.0Zr alloy in high temperature deformation.

scholarly journals Determining a Flow Stress Model for High Temperature Deformation of Ti-6Al-4V

2015 ◽  
Vol 828-829 ◽  
pp. 441-446 ◽  
Author(s):  
E. Calvert ◽  
J. Pollard ◽  
M. Jackson ◽  
B. Wynne ◽  
Richard Thackray
Keyword(s):  
Flow Stress ◽  
Hot Deformation ◽  
True Strain ◽  
Extrusion Process ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Strain Rates ◽  
Stress Model ◽  
Specific Flow ◽  
Flow Stress Model

In some commercial titanium extrusion practices, twisting of the extrudate can occur, which can result in the need to crop the back and front end of the extruded material, thereby reducing yield and increasing material losses. Understanding more about the behaviour of material during the extrusion process, and investigating the cause of defects such as twisting by use of finite element (FE) modelling techniques could help to reduce these losses, improve the productivity of the extrusion process, and the overall quality of the material produced. One of the most important components of FE techniques for hot deformation is the type of flow stress model that is used in the simulations. In this investigation isothermal uniaxial compression testing was performed on cylindrical specimens of Ti-6Al-4V at temperatures ranging from 950 °C to 1200°C and strain rates of 0.1 s-1 to 50 s-1, to produce true stress against true strain and load against die travel curves which were subsequently used to develop a new specific flow stress model for use in hot deformation above the beta transus, which can ultimately be applied to the hot extrusion of Ti-6Al-4V. From analysis of this data it was concluded that flow softening and work hardening do not occur during deformation, and that low friction conditions exist between the material and the tooling. The activation energy for deformation was found to be 193178 J.mol-1, and the flow stress model was shown to give a good fit to the raw data at low strain rates, but this relationship broke down at higher strain rates. Finally the importance of generating a flow stress model specific to a particular operation, and set of experimental data, rather than relying on existing data available in the literature is demonstrated.

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