Occurrence of Dynamic Alpha-Phase Nucleation in Ti-5553 during Hot Deformation

2014 ◽  
Vol 922 ◽  
pp. 149-154 ◽  
Author(s):  
Ameth Maloum Fall ◽  
David Piot ◽  
Frank Montheillet ◽  
Sandra Andrieu
Keyword(s):  
Hot Deformation ◽  
Peak Stress ◽  
Nucleation And Growth ◽  
Alpha Phase ◽  
Flow Softening ◽  
Compression Tests ◽  
Two Phase ◽  
Flow Response ◽  
Phase Nucleation ◽  
Dynamic Nucleation

This paper discusses the microstructural changes during hot deformation, mainly dynamic nucleation and growth of a precipitates, occurring in the b metastable titanium alloy Ti-5553 (Ti–5Al–5Mo–5V–3Cr–0.5Fe). The effect of process variables on flow response and microstructure evolution during hot working of the alloy with initial bimodal microstructure was established using isothermal hot-compression tests. Testing was conducted at 4 strain rates between 0.001 and 1 s−1and 5 temperatures between 720 °C and 850 °C, on material with prior b grain size of 450 μm, a nodular size of 3 µm and a known primary a-phase fraction. All flow curves exhibited a peak stress followed by moderate flow softening in the two-phase domain. Flow softening was interpreted in terms of deformation heating and substructure or texture evolutions. The dependence on strain rate and temperature of the kinetics of dynamic a-phase nucleation during straining is complex and appears to be of second-order importance compared to the effects of strain. This suggests that the nucleation and growth of a phase in the temperature range between 720 °C and 990 °C results from a mixed-mode displacive-diffusional transformation, similar to the austenite / ferrite transformation above the Ae3 temperature reported by some authors.

Hot working of SP-700 titanium alloy with lamellar α + β starting structure using a processing map

2020 ◽  
Vol 111 (4) ◽  
pp. 297-306
Author(s):  
Amir Hosein Sheikhali ◽  
Maryam Morakkabati
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Hot Deformation ◽  
Processing Map ◽  
Microstructural Analysis ◽  
Shear Bands ◽  
Alpha Phase ◽  
Strain Rates ◽  
Compression Tests ◽  
Temperature Range

Abstract In this study, hot deformation behavior of SP-700 titanium alloy was investigated by hot compression tests in the temperature range of 700-9508C and at strain rates of 0.001, 0.1, and 1 s-1. Final mechanical properties of the alloy (hot compressed at different strain rates and temperatures) were investigated using a shear punch testing method at room temperature. The flow curves of the alloy indicated that the yield point phenomenon occurs in the temperature range of 800- 9508C and strain rates of 0.1 and 1 s-1. The microstructural analysis showed that dynamic globularization of the lamellar α phase starts at 7008C and completes at 8008C. The alpha phase was completely eliminated from b matrix due to deformation- induced transformation at 8508C. The microstructure of specimens compressed at 8508C and strain rates of 0.001 and 0.1 s-1showed the serration of beta grain boundaries, whereas partial dynamic recrystallization caused a necklace structure by increasing strain rate up to 1 s-1. The specimen deformed at 7008C and strain rate of 1 s-1was located in the instability region and localized shear bands formed due to the low thermal conductivity of the alloy. The processing map of the alloy exhibited a peak efficiency domain of 54% in the temperature range of 780-8108C and strain rates of 0.001- 0.008 s-1. The hot deformation activation energy of the alloy in the α/β region (305.5 kJ mol-1) was higher than that in the single-phase β region (165.2 kJ mol-1) due to the dynamic globularization of the lamellar a phase.

Explosive crystallization phenomena in SOI structures

1989 ◽  
Vol 4 (6) ◽  
pp. 1473-1479 ◽  
Author(s):  
H. D. Geiler ◽  
M. Wagner ◽  
E. Glaser ◽  
G. Andrä ◽  
D. Wolff ◽  
...  
Keyword(s):  
Solid Phase ◽  
Amorphous Layer ◽  
Nucleation And Growth ◽  
Time Interval ◽  
Two Phase ◽  
Pulse Technique ◽  
Explosive Crystallization ◽  
Crystalline Nucleus ◽  
Phase Nucleation ◽  
Temperature Time

Using the double pulse technique with two synchronized lasers, we studied the conditions of ignition and evolution of explosive crystallization. The structure of the resulting crystallized layers is analyzed by TEM. Results of calculations are reported describing the development of the two phase fronts: amorphous/molten and molten/crystalline. It is shown that the system takes more than 500 ns to reach the steady state. The experimental results support the model of creating first a melt nucleus in the amorphous layer followed by the formation of the crystalline nucleus in the molten sphere. Competitive solid phase nucleation and growth in the amorphous layer limit the temperature-time interval of melt nucleation. Defined explosively crystallized areas in laterally structured SOI layers are presented.

Mechanical Behaviour and Microstructure Evolution of Severely Deformed Two-Phase Titanium Alloys

2008 ◽  
Vol 584-586 ◽  
pp. 771-776 ◽  
Author(s):  
Sergey V. Zherebtsov ◽  
Sergey Mironov ◽  
Maria A. Murzinova ◽  
S. Salishchev ◽  
S. Lee Semiatin
Keyword(s):  
Titanium Alloys ◽  
Microstructure Evolution ◽  
High Strain ◽  
Beta Phase ◽  
Alpha Phase ◽  
Steady State Flow ◽  
Two Phase ◽  
Globular Microstructure ◽  
Flow Response ◽  
Alpha Beta

Microstructure evolution and mechanical behavior of alpha/beta Ti-6Al-4V (VT6) and near-beta Ti-5Al-5Mo-5V-1Cr-1Fe (VT22) titanium alloys during uniaxial compression at 600°C to a high strain of 70% was studied. The plastic-flow response for both alloys is characterized by successive stages of strain hardening, flow softening, and steady-state flow. During compression the lamellae spheroidized to produce a partially globular microstructure. Globularization in VT6 is associated with the loss of the initial Burgers-type coherency between the alpha and beta phases and the subsequent individual deformation of each phase. The misorientations of boundaries increase to the high-angle range by means of the accumulation of lattice dislocations. In VT22 alloy the alpha phase evolves similar to that in VT6 alloy, while in the beta phase mainly low-angle boundaries are observed even after 70 pct. reduction.

scholarly journals Hot Deformation Behavior and Processing Maps of Fe-30Mn-0.11C Steel

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1940 ◽  
Author(s):  
Jianmei Kang ◽  
Yuhui Wang ◽  
Zhimeng Wang ◽  
Yiming Zhao ◽  
Yan Peng ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
True Strain ◽  
Peak Stress ◽  
Strain Rates ◽  
Processing Maps ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
High Deformation

Hot deformation behavior of Fe-30Mn-0.11C steel was investigated. Hot compression tests were carried out at various temperatures ranging from 800 °C to 1200 °C and at different strain rates of 0.01 s−1 to 10 s−1. The constitutive equation based on peak stress was established. Hot processing maps at different strains and recrystallization diagrams were also established and analyzed. The results show that dynamic recrystallization easily occur at high deformation temperatures and low strain rates. Safe and unstable zones are determined at the true strain of 0.6 and 0.7, and the hot deformation process parameters of partial dynamic recrystallization of the tested steel are also obtained.

Influence of δ Phase Content on Hot Deformation Behavior of Ni-Based Superalloy IN718

2011 ◽  
Vol 314-316 ◽  
pp. 1159-1162
Author(s):  
Hai Yan Zhang ◽  
Shi Hong Zhang ◽  
Ming Cheng
Keyword(s):  
Hot Deformation ◽  
Deformation Behavior ◽  
Peak Stress ◽  
Hot Working ◽  
Peak Strain ◽  
Phase Content ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Deformation Activation Energy ◽  
Δ Phase

The effect of δ phase content on the hot deformation behavior of alloy IN718 has been investigated using isothermal compression tests. The results indicated that the δ phase has a significant effect on the deformation behavior of alloy IN718 during hot working. After the peak stress, the decreasing speed of the stress raises as the increase in the δ phase content. The deformation activation energy for alloy IN718 increases with the raise of the δ phase content. And the peak strain for the alloy decreases with the increase of the δ phase content, which indicates that the δ phase can stimulate the occurrence of dynamic recrystallization during hot working.

Hot Deformation Behavior of the 30%Mo/Cu-Al2O3 Composite Prepared by Vacuum Hot-Pressed Sintering

2011 ◽  
Vol 117-119 ◽  
pp. 893-896
Author(s):  
Yong Liu ◽  
Yong Wei Sun ◽  
Bao Hong Tian ◽  
Jiang Feng ◽  
Yi Zhang
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Flow Behavior ◽  
Peak Stress ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Compression Tests ◽  
Hot Deformation Behavior

Hot deformation behavior of the 30%Mo/Cu-Al2O3 composite was investigated by hot compression tests on Gleeble-1500D thermal simulator in the temperature ranges of 450~750°C and the strain rate ranges of 0.01~5s-1, as the total strain is 0.7. The results show that the peak stress increases with the decreased deformation temperature or the increased strain rate. Based on the true stress-strain curves, the established constitutive equation represents the high-temperature flow behavior of the composite, and the calculated flow stresses are in good agreement with the high- temperature deformation experimental results.

scholarly journals Characterization of Hot Deformation Behavior in a 13% Chromium Steel

2018 ◽  
Vol 941 ◽  
pp. 458-467
Author(s):  
Nima Safara Nosar ◽  
Fredrik Sandberg ◽  
Göran Engberg
Keyword(s):  
Hot Deformation ◽  
Deformation Behavior ◽  
Peak Stress ◽  
Chromium Steel ◽  
Hot Compression ◽  
Strain Rates ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Hollomon Parameter

The behavior of a 13% chromium steel subjected to hot deformation has been studied by performing hot compression tests in the temperature range of 850 to 12000C and at strain rates from 0.01 to 10 s-1. The uniaxial hot compression tests were performed on a Gleeble thermo-mechanical simulator. The best function that fits the peak stress for the material and its relation to the Zener-Hollomon parameter (Z) is derived. The average activation energy of this alloy in the entire test domain was found to be about 557 [kJmol-1] and the dynamic recrystallization (DRX) kinetics was studied to find the fraction DRX during deformation.

Work Hardening and Flow Softening of γ-TiAl Containing Ni

2004 ◽  
Vol 449-452 ◽  
pp. 833-836 ◽  
Author(s):  
Jian Hui Zhang ◽  
Kenong Xia ◽  
Erik Strom ◽  
Zeng Yong Zhong ◽  
Chang Hai Li
Keyword(s):  
Work Hardening ◽  
Flow Behavior ◽  
Peak Stress ◽  
True Stress ◽  
Flow Softening ◽  
Strain Rates ◽  
Isothermal Compression ◽  
Compression Tests ◽  
Steady State Flow ◽  
Ni Addition

This paper presents the true stress - strain curves and data analyses of a Ni-containing TiAl and its reference alloy based on the isothermal compression tests at 1000°C and 0.01 - 1.0s-1strain rates. The results show that the minor Ni addition makes the flow softening coming sooner and therefore significantly lowers the peak stress. Those effects, in addition with a better balance between the work hardening and flow softening during hot deformation, improve the steady state flow behavior of TiAl. The Ni-influence mechanisms are also suggested based on the TEM observation of dislocation configurations and lamellar breakdown during the deformation.

High Temperature Deformation Behavior and Microstructure Preparation of Cu-Ni-Si-P Alloy

2011 ◽  
Vol 704-705 ◽  
pp. 135-140 ◽  
Author(s):  
Yi Zhang ◽  
Bao Hong Tian ◽  
Ping Liu
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Deformation Temperature ◽  
Peak Stress ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Compression Tests ◽  
Hollomon Parameter ◽  
Temperature Ranges

The hot deformation behavior of Cu-Ni-Si-P alloy have been investigated by means of isothermal compression tests on a Gleeble-1500D thermal mechanical simulator in the temperature ranges of 873-1073 K and strain rate ranges of 0.01-5s-1. The results show that the dynamic recryatallization occurs in Cu-Ni-Si-P alloy during hot deformation. The peak stress during hot deformation can be described by the hyperbolic sine function. The influence of deformation temperature and strain rate on the peak stress can be represented using the Zener-Hollomon parameter. Moreover, the activation energy for hot deformation of Cu-Ni-Si-P alloy is determined to be 485.6 kJ / mol within the investigated ranges of deformation temperature and strain rate. The constitutive equation of the Cu-Ni-Si-P alloy is also established. Keywords: Cu-Ni-Si-P alloy; Hot deformation; Dynamic recrystallization; Zener-Hollomon parameter.

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