Accelerated flow softening and dynamic transformation of Ti-6Al-4V alloy in two-phase region during hot deformation via coarsening α grain

2020 ◽  
Vol 36 ◽  
pp. 160-166 ◽  
Author(s):  
Xiankun Ji ◽  
Baoqi Guo ◽  
Fulin Jiang ◽  
Hong Yu ◽  
Dingfa Fu ◽  
...  
Keyword(s):  
Hot Deformation ◽  
Phase Region ◽  
Flow Softening ◽  
Two Phase ◽  
Dynamic Transformation ◽  
Accelerated Flow

Transformation of α→β During Hot Deformation in the Two-Phase Region of Ti–6Al–2Zr–1Mo–1V Alloy

2021 ◽  
pp. 1791-1803
Author(s):  
Lei Chen ◽  
Qifei Zhang ◽  
Qun Li ◽  
Miao Jin ◽  
Shiyan Zhao ◽  
...  
Keyword(s):  
Hot Deformation ◽  
Phase Region ◽  
Two Phase

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.

Optimisation of Precipitation for the Development of Improved Wrought Fe3Al-based Alloys

2004 ◽  
Vol 842 ◽  
Author(s):  
Satoru Kobayashi ◽  
Stefan Zaefferer ◽  
André Schneider
Keyword(s):  
Grain Refinement ◽  
Hot Deformation ◽  
Single Phase ◽  
Fine Particles ◽  
Phase Region ◽  
Air Cooling ◽  
Two Phase ◽  
Kinetics Of ◽  
Very High ◽  
Grain Refinement Strengthening

ABSTRACTEffect of TiC precipitates on the kinetics of static recrystallisation has been studied by using a Fe-26Al-5Cr (at%) single-phase (α:A2/B2/D03) alloy and two-phase (α+TiC) alloys with different amounts of TiC precipitates. Based on the results, a desirable thermo-mechanical processing is proposed for the development of wrought Fe3Al-based alloys with strengthening MC carbides.In the alloys with a high amount of TiC, needle-like TiC precipitates with 1–10 μm in length formed during air-cooling after homogenisation. Hot deformations with such large precipitates cause inhomogeneous deformation around the particles, leading to particle stimulated nucleation (PSN) and hence accelerate recrystallisation.The occurrence of PSN is harmful for the embrittlement problem, i.e. ductility drastically decreases when recrystallisation occurs, but useful for grain refinement. The following process is proposed to accomplish grain refinement, strengthening by precipitates and avoidance of the embrittlement: hot deformation with a large amount of precipitates to make grain refinement possible by using PSN, followed by hot deformation with a small amount of precipitates near α single-phase region and a subsequent heat treatment to obtain fine precipitates. The fine particles would also act to pin the boundaries of growing grains, thus leading to extended recovery rather than recrystallisation. This process is difficult to carry out in the (Fe-26Al-5Cr)-TiC system because the temperature necessary to enable precipitation is very high and the kinetics is quick. The precipitation temperature is significantly decreased by replacing TiC by VC or MoC.

scholarly journals Post-dynamic α to β phase transformation and reverse transformation of Ti-5Al-3V alloy after hot deformation in two phase region

2020 ◽  
Vol 188 ◽  
pp. 108466 ◽  
Author(s):  
Xiankun Ji ◽  
Hong Yu ◽  
Baoqi Guo ◽  
Fulin Jiang ◽  
Dingfa Fu ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Hot Deformation ◽  
Phase Region ◽  
Reverse Transformation ◽  
Two Phase ◽  
Β Phase

Dynamic transformation of Ti–6Al–4V during torsion in the two-phase region

2018 ◽  
Vol 53 (12) ◽  
pp. 9305-9315 ◽  
Author(s):  
Baoqi Guo ◽  
S. L. Semiatin ◽  
John J. Jonas ◽  
Stephen Yue
Keyword(s):  
Phase Region ◽  
Two Phase ◽  
Dynamic Transformation

Hot Deformation Behavior of Near-α Ti-Fe Alloy in (α+β) Two-Phase Region with Different Fe Content

2010 ◽  
Vol 638-642 ◽  
pp. 310-314
Author(s):  
Behrang Poorganji ◽  
Makoto Yamaguchi ◽  
Yoshio Itsumi ◽  
Katsushi Matsumoto ◽  
Tomofumi Tanaka ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
Interlamellar Spacing ◽  
Phase Region ◽  
Strain Rates ◽  
Two Phase ◽  
Β Phase ◽  
Α Phase ◽  
Fe Content

In the present study, microstructure evolution of Ti-Fe alloys with different Fe content between 0.2-1.5mass% during hot deformation in (α+β) two-phase region is studied with focusing on effect of phase volume fraction at different deformation temperatures and strain rates. Hot deformation was conducted on the specimens quenched after β solutionizing at 1173K for 1.2ks at 1108, 1073 and 948K, by uniaxial compression by 50% at various strain rates ranged from 1 to 10-4 s-1. Initial structures are (α+β) lamellar structures of fine interlamellar spacing and colony sizes. Increase in Fe content results in increasing the fraction of the β phase at the given deformation temperature. Either colony size or interlamellar spacing is coarser at higher temperatures. At the higher deformation temperature where β phase fraction is larger, dynamic recovery of β phase is a major deformation mechanism while at a lower temperature, i.e., a higher α fraction, dynamic recrystallization of α phase occurs predominantly. It is concluded that critical strain needed for occurrence of dynamic recrystallization is decreased by increasing fraction of the α phase at the same deformation temperature, i.e., by decreasing Fe content. Furthermore, by increasing strain rate grain size of the recrystallized α is decreased.

Hot deformation behavior of Zr-1Nb alloy in two-phase region –microstructure and mechanical properties

2018 ◽  
Vol 741 ◽  
pp. 281-292 ◽  
Author(s):  
K.K. Saxena ◽  
K.S. Suresh ◽  
R.V. Kulkarni ◽  
K.V. Mani Krishna ◽  
V. Pancholi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Phase Region ◽  
Hot Deformation Behavior ◽  
Two Phase ◽  
Microstructure And Mechanical Properties
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