scholarly journals Deformation behaviour of beta phase with similar chemical composition in beta and alpha+beta titanium alloys

2020 ◽  
Vol 321 ◽  
pp. 11082
Author(s):  
Xin Xu ◽  
Ioannis Bantounas ◽  
David Dye
Keyword(s):  
Yield Strength ◽  
Titanium Alloys ◽  
Deformation Behaviour ◽  
Beta Phase ◽  
Total Elongation ◽  
Deformation Twinning ◽  
Transformation Induced Plasticity ◽  
Β Phase ◽  
Beta Titanium ◽  
Similar Chemical

Twinning-induced plasticity (TWIP) and transformation-induced plasticity (TRIP) in β titanium alloys have been attracting significant interest, since they offer the possibility to provide work hardening and thus, ductility. Here a quaternary Ti-Al-Cr-Mo metastable β alloy has been designed with an excellent combination of strength ductility that exploits the TWIP and TRIP effects. Its engineering yield strength, tensile strength and total elongation are 737 MPa, 999 MPa and 24%, respectively. In order to increase the yield strength but retain ductility, an attempt has been carried to design an α+β alloy with a bimodal microstructure. The composition of the β phase in the α+β alloy was tuned to provide deformation twinning of the β phase. The content of the major α and β stabilising elements, i.e. Al, Cr and Mo, in the β phase of the α+β alloy was similar to the β alloy, but the deformation twinning was not observed in the β phase. It is suggested that this may be due to over-stabilisation of the β phase and/or to the different stress/strain and dislocation distributions in the α+β alloy caused by the presence of β phase.

scholarly journals Beta Ti-45Nb and Ti-50Nb Alloys Produced by Powder Metallurgy for Aerospace Application

2010 ◽  
Vol 660-661 ◽  
pp. 405-409 ◽  
Author(s):  
G.V. Martins ◽  
Cosme Roberto Moreira Silva ◽  
C.A. Nunes ◽  
Vladimir J. Trava-Airoldi ◽  
L.A. Borges ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Powder Metallurgy ◽  
Titanium Alloys ◽  
Substantial Reduction ◽  
Weight Ratio ◽  
High Strength ◽  
Beta Phase ◽  
Cold Isostatic Pressing ◽  
Specific Mass ◽  
Beta Titanium

Beta titanium alloys parts are used on advanced aerospace systems because of their high strength to weight ratio and excellent corrosion resistance. Production of powder metallurgy titanium alloys components may lead to a substantial reduction in the cost, compared to those produced by conventional cast and wrought processes, because additional working operations and material waste can be avoided. In this work, beta Ti-45Nb and Ti-50Nb were produced by the blended elemental technique, followed by uniaxial and cold isostatic pressing with subsequent densification by sintering. Sintered samples were characterized for phase composition by XRD, microstructure by SEM, hardness by Vickers indentation, specific mass by the Archimedes method and elastic modulus by resonance ultrasound. The sintered samples presented only the beta phase, higher hardness and lower elastic modulus when compared to Ti6Al4V alloy and experimental specific mass value near theoretical specific mass. These characteristics are adequate for application on several aerospace parts.

Hot Deformation and Dynamic Recrystallization of the Beta Phase in Titanium Alloys

2012 ◽  
Vol 706-709 ◽  
pp. 127-134 ◽  
Author(s):  
Frank Montheillet ◽  
L. Pallot ◽  
David Piot
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Titanium Alloys ◽  
Grain Boundaries ◽  
Strain Range ◽  
Beta Phase ◽  
High Rate ◽  
Crystallographic Structure ◽  
Continuous Dynamic Recrystallization ◽  
Β Phase

Due to the high rate of dynamic recovery associated with the large stacking fault energy of the bcc structure, classical "discontinuous" dynamic recrystallization, occurring by nucleation and growth of new grains is not observed in the β phase of titanium alloys. Instead, the following mechanisms take place: at low and moderate strains (ε < 1), the original flattened (compression) or sheared (torsion) grains are still recognizable, although their boundaries are strongly serrated. In this strain range, grain size (thickness) results from both the convection and the migration of grain boundaries. At intermediate strains, "geometric" dynamic recrystallization leading to "pinching off" events of the original grains is observed, whereas at larger strains (ε > 5), grain fragmentation occurs by the generation of new grain boundaries ("continuous" dynamic recrystallization). The associated flow stress often exhibits pronounced softening and the resulting (equiaxed) grain size can be much smaller than the initial one. It is worth to note that a very similar sequence of mechanisms takes place in ferritic steels, as well as in aluminium alloys, in spite of their different crystallographic structure. In this paper, the above mechanisms will be illustrated by a set of data pertaining to titanium alloys.

Fundamental Studies of Beta Phase Decomposition Modes in Titanium Alloys.

1988 ◽  
Author(s):  
H. I. Aaronson ◽  
A. M. Dalley ◽  
T. Furuhara ◽  
Y. Mou
Keyword(s):  
Titanium Alloys ◽  
Beta Phase ◽  
Phase Decomposition

Effect of Grain Size on Deformation Twinning Behavior of Ti6Al4V Alloy

2015 ◽  
Vol 830-831 ◽  
pp. 337-340
Author(s):  
Ashish Kumar Saxena ◽  
Manikanta Anupoju ◽  
Asim Tewari ◽  
Prita Pant
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Deformation Behaviour ◽  
Air Cooling ◽  
Specific Strength ◽  
Aerospace Applications ◽  
Β Phase ◽  
Plastic Deformation Behavior

An understanding of the plastic deformation behavior of Ti6Al4V (Ti64) is of great interest because it is used in aerospace applications due to its high specific strength. In addition, Ti alloys have limited slip systems due to hexagonal crystal structure; hence twinning plays an important role in plastic deformation. The present work focuses upon the grain size effect on plastic deformation behaviour of Ti64. Various microstructures with different grain size were developed via annealing of Ti64 alloy in α-β phase regime (825°C and 850°C) for 4 hours followed by air cooling. The deformation behavior of these samples was investigated at various deformation temperature and strain rate conditions. Detailed microstructure studies showed that (i) smaller grains undergoes twinning only at low temperature and high strain rate, (ii) large grain samples undergo twinning at all temperatures & strain rates, though the extent of twinning varied.

The effect of ternary additions on the decompositon of metastable beta-phase titanium alloys

1971 ◽  
Vol 2 (2) ◽  
pp. 477-484 ◽  
Author(s):  
J. C. Williams ◽  
B. S. Hickman ◽  
D. H. Leslie
Keyword(s):  
Titanium Alloys ◽  
Beta Phase ◽  
Ternary Additions ◽  
Metastable Beta

scholarly journals Development of α+β-type biomedical Ti–Nb alloys with high oxygen content

2020 ◽  
Vol 321 ◽  
pp. 05003
Author(s):  
K. Ueda ◽  
M. Omiya ◽  
Y. Hirose ◽  
T. Narushima
Keyword(s):  
Oxygen Content ◽  
Low Cost ◽  
Total Elongation ◽  
Ti Alloy ◽  
High Oxygen Content ◽  
Β Phase ◽  
Α Phase ◽  
Heat Treated ◽  
Iced Water ◽  
Nb Content

Ti-(5–20)Nb-(0.5–1)O alloys (mass%) were investigated for developing low-cost biomedical α+β-type Ti alloy. Ti-(5, 10, 15, 20)Nb-(0.5, 0.75, 1)O alloys (mass%) were arc-melted and forged into bars. The forged alloy bars were heat-treated at 873 to 1373 K for 3.6 ks in an Ar atmosphere and quenched in iced water. β transus (Tβ) of the Ti-Nb-O alloys decreased with increasing Nb content. An increase in the oxygen content led to an increase in Tβ. After quenching, the formation of α′ martensite was observed in Ti-5Nb-yO alloys. An increase in the Nb content to 10 mass% led to the formation of α′ and α″ martensites. A further increase in the Nb content to 15 and 20mass% resulted in the formation of more α″ martensites. The boundary temperature for the formation of α′ and α″ martensite in the Ti-10Nb-yO alloys increased with increasing oxygen content, because oxygen enhances the Nb distribution to the β phase. The ultimate tensile strength of the Ti-xNb-0.75O alloys heattreated to obtain the α-phase fraction (fα) of 0.5 was over 1000 MPa, except for the Ti-15Nb-0.75O alloy. The total elongation decreased with increasing Nb content. The Ti-5Nb-0.75O alloy exhibited excellent strength-ductility balance as a low-cost α+β-type biomedical Ti alloy.

Structural and Compositional Characteristics of Isothermal Omega Phase in Beta Titanium Alloys

2016 ◽  
pp. 559-562 ◽  
Author(s):  
Yufeng Zheng ◽  
Talukder Alam ◽  
Robert E.A. Williams ◽  
Soumya Nag ◽  
Rajarshi Banerjee ◽  
...  
Keyword(s):  
Titanium Alloys ◽  
Omega Phase ◽  
Beta Titanium ◽  
Beta Titanium Alloys
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