Precipitation of β' Phase in a Low Cost Beta Titanium Alloy

Precipitation behavior of a metastable β Ti alloy, Ti-6.8Mo-4.5Fe-1.5Al(masss%), during two-step aging has been investigated. Supersaturated β phase after solution treatment decomposes into β+ω phases during the first aging at 300°C for 2ks. β′ phase is observed during the second aging at 500°C for 50s. It is suggested that reverse transformation of the ω phase to β phase during the second aging at 500°C for 50s gives rise to solute-lean and –rich regions in the β phase, and that β′ phase is formed in the solute-rich region. β′ phase being coherent with β phase has larger lattice parameter than β phase. β′ phase acts as nucleation site for α phase, and accelerates the nucleation of α phase.

Download Full-text

Phase transformations during continuous heating: effect of Sn addition on the microstructure of Ti-13Mo alloy

MATEC Web of Conferences ◽

10.1051/matecconf/202032105017 ◽

2020 ◽

Vol 321 ◽

pp. 05017

Author(s):

M.G. de Mello ◽

F.H. da Costa ◽

R. Caram

Keyword(s):

Lattice Parameter ◽

Continuous Heating ◽

Phase Precipitation ◽

Heating Rates ◽

Scanning Calorimetry ◽

Β Phase ◽

Ω Phase ◽

Α Phase ◽

Heat Treated ◽

Kinetics Of

The addition of Sn to the Ti-Mo system can diminish the formation of ω phase and slow down the precipitation kinetics of α phase due to the low atomic diffusivity of Sn atoms in Ti. To explore α phase precipitation in Ti-13Mo and Ti-13Mo-6Sn (wt.%) alloys, differential scanning calorimetry (DSC) was applied using different heating rates to determine ω phase dissolution, α phase precipitation and β transus temperatures. The DSC results were then used to determine the aging heat treatment temperatures. Samples were heat-treated at 600 °C for 1 h and 24 h to examine microstructure features. The addition of Sn to Ti-13Mo alloy was found to increase the β phase lattice parameter, increasing β transus temperatures and resulting in microstructures with heterogeneous and coarser α phase precipitation.

Download Full-text

Microstructure and Tensile Properties of Boron-Doped Beta Titanium Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.849.287 ◽

2016 ◽

Vol 849 ◽

pp. 287-294 ◽

Cited By ~ 1

Author(s):

Rong Chen ◽

Yang Yu ◽

Song Xiao Hui ◽

Wen Jun Ye

Keyword(s):

Tensile Deformation ◽

Boundary Migration ◽

Solution Treatment ◽

Grain Boundary Migration ◽

Beta Titanium Alloy ◽

Β Phase ◽

Boron Doped ◽

Beta Titanium ◽

High Level ◽

Strength And Ductility

The microstructural evolution and the mechanical properties of Ti-2Al-9.2Mo-2Fe-0.1B alloy during solution treatment and aging have been investigated. The experimental results showed that the addition of boron resulted in the formation of TiB phase and high level of recrystallization during hot deformation. TiB phase did not moved with the grain boundary migration during solution treatment. On aging, a little of α phase nucleated from the interface of TiB and β phase. The existence of TiB phase could offer the source of cracks during tensile deformation, resulting in the ductility decline of the alloy. In addition, the alloy which aged at 550°C and 600°C for 2h could obtain a good combination of strength and ductility, with 1100~1300MPa of ultimate strength and exceeding 7% of elongation.

Download Full-text

EFFECT OF CARBON AND OXYGEN ADDITIONS ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Ti-4.3Fe-7.1Cr-3Al ALLOY

International Journal of Modern Physics B ◽

10.1142/s0217979209060075 ◽

2009 ◽

Vol 23 (06n07) ◽

pp. 814-820

Author(s):

XIPING SONG ◽

LONG CHEN ◽

KUN LI ◽

GUOLIANG CHEN

Keyword(s):

Mechanical Properties ◽

Hot Rolling ◽

Low Cost ◽

Strength Increase ◽

Carbon Addition ◽

Phase Precipitation ◽

Beta Titanium Alloy ◽

Α Phase ◽

Microstructure And Mechanical Properties ◽

Beta Titanium

The effects of carbon and oxygen additions on the microstructure and mechanical properties of a new type low-cost beta titanium alloy Ti -4.3 Fe -7.1 Cr -3 Al have been studied. The results showed that with the carbon addition the grain size was refined significantly, followed by the tensile strength increase and ductility improvement. At 0.2 wt.% carbon addition the 0.2%YS increased by 22% and elongation increased to a peak value of 23%. Also with the carbon addition the oxygen content in the alloy could be allowed to reach 0.2wt.% without tensile property decrease. After ageing treatment, it was found that ageing temperature other than carbon content played a key role on the α-phase precipitation and ageing hardness. The hot-rolling deformation accelerated the ageing response. The optimal ageing process was decided to be 500°C for 1h under the pretreatment of 850°C hot-rolling followed by immediately water quenching. The reasons for these improvements were discussed in terms of the carbide pinning and α-phase precipitation.

Download Full-text

TiFe Precipitation Behavior and its Effect on Strengthening in Solution Heat-Treated Ti-5Al-3.5Fe During Isothermal Aging

Metals ◽

10.3390/met8110875 ◽

2018 ◽

Vol 8 (11) ◽

pp. 875 ◽

Cited By ~ 1

Author(s):

Hye-Jeong Choe ◽

Jong Won ◽

Yong-Taek Hyun ◽

Ka Lim ◽

Seog-Young Yoon

Keyword(s):

Phase Transformation ◽

Isothermal Aging ◽

Nucleation Site ◽

Precipitation Kinetics ◽

Precipitation Behavior ◽

Β Phase ◽

Α Phase ◽

Nucleation Sites ◽

Heat Treated ◽

Interphase Boundaries

We investigated the TiFe precipitation behavior of solution heat-treated Ti-5Al-3.5Fe during isothermal aging, quantified the effect of precipitation on strengthening by evaluating the hardness, and compared it to the effect of Ti3Al precipitation in Ti-6Al-4V. TiFe precipitates formed both at grain boundaries (GBs) and within the grain matrices. Phase transformation from the β to α phase also occurred during isothermal aging; this transformation generated lamellar interphase boundaries between the transformed α phase and remaining β phase in prior β grains. These interphase boundaries enabled the formation of in-grain TiFe precipitates by acting as a nucleation site. GB precipitation did not require prior β → α phase transformation to generate nucleation sites (i.e., interphase boundaries), so TiFe precipitation could occur immediately upon isothermal aging. Thus, GB precipitation proceeded more quickly than in-grain precipitation; as a result, precipitates were larger and more spherical at the GBs than in grains. The strengthening behavior exhibited by TiFe precipitation differed obviously from that caused by Ti3Al precipitation in Ti-6Al-4V because of its differing precipitation kinetics and related microstructural evolution.

Download Full-text

Decomposition of the metastable beta titanium alloy Ti-15-3

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075117 ◽

1983 ◽

Vol 41 ◽

pp. 264-265

Author(s):

Y. L. Chen ◽

S. Fujlshiro

Keyword(s):

Low Cost ◽

High Strength ◽

Alpha Phase ◽

Thick Sheet ◽

Omega Phase ◽

Beta Titanium Alloy ◽

Beta Titanium ◽

Beta Matrix ◽

Metastable Beta ◽

Very High

Metastable beta titanium alloys have been known to have numerous advantages such as cold formability, high strength, good fracture resistance, deep hardenability, and cost effectiveness. Very high strength is obtainable by precipitation of the hexagonal alpha phase in a bcc beta matrix in these alloys. Precipitation hardening in the metastable beta alloys may also result from the formation of transition phases such as omega phase. Ti-15-3 (Ti-15V- 3Cr-3Al-3Sn) has been developed recently by TIMET and USAF for low cost sheet metal applications. The purpose of the present study was to examine the aging characteristics in this alloy.The composition of the as-received material is: 14.7 V, 3.14 Cr, 3.05 Al, 2.26 Sn, and 0.145 Fe. The beta transus temperature as determined by optical metallographic method was about 770°C. Specimen coupons were prepared from a mill-annealed 1.2 mm thick sheet, and solution treated at 827°C for 2 hr in argon, then water quenched. Aging was also done in argon at temperatures ranging from 316 to 616°C for various times.

Download Full-text

Effect of Cold Machining Process on the Property and Microstructure of Ti-5Mo-5V-8Cr-3Al Strip

Materials Science Forum ◽

10.4028/www.scientific.net/msf.788.134 ◽

2014 ◽

Vol 788 ◽

pp. 134-137 ◽

Cited By ~ 1

Author(s):

Pei Tong Ni ◽

Li Peng Zhou ◽

Bao Liang Bai ◽

Ming Chen Han ◽

Mei Sheng Zhu

Keyword(s):

Solution Treatment ◽

Aging Treatment ◽

High Strength ◽

Machining Process ◽

Beta Titanium Alloy ◽

Cold Forming ◽

Corrugated Shell ◽

Beta Titanium ◽

Gas Quenching ◽

Metastable Beta

Metastable beta titanium alloy Ti-5Mo-5V-8Cr-3Al, with high-strength, favorite ductility and outstanding capacity of cold forming and welding, has been found the applications in sheet metal component, pressure vessel, corrugated shell and cold heading rivet at the temperature lower than 350°C. In the present paper, the effect of cold machining deformation rate and heat treatment process on the properties and microstructures of Ti-5Mo-5V-8Cr-3Al strip were investigated. The results revealed that excellent comprehensive mechanical properties could be achieved with the alloy by reasonable cold machining process and with solution treatment at 800°C followed by gas quenching. Upon a solution and aging treatment at 480°C, the alloy performed favorite plasticity and high ultimate tensile strength of 1250MPa.

Download Full-text

The Effect of Heat Treatment on the Microstructure and Mechanical Properties of the Novel Low-Cost Ti-3Al-5Mo-4Cr-2Zr-1Fe Alloy

Materials ◽

10.3390/ma13173798 ◽

2020 ◽

Vol 13 (17) ◽

pp. 3798

Author(s):

Meng Sun ◽

Dong Li ◽

Yanhua Guo ◽

Ying Wang ◽

Yuecheng Dong ◽

...

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Aging Time ◽

Volume Fraction ◽

Low Cost ◽

Solution Treatment ◽

Solution Temperature ◽

The Novel ◽

Α Phase ◽

The Cost

In order to reduce the cost of titanium alloys, a novel low-cost Ti-3Al-5Mo-4Cr-2Zr-1Fe (Ti-35421) titanium alloy was developed. The influence of heat treatment on the microstructure characteristics and mechanical properties of the new alloy was investigated. The results showed that the microstructure of Ti-35421 alloy consists of a lamina primary α phase and a β phase after the solution treatment at the α + β region. After aging treatment, the secondary α phase precipitates in the β matrix. The precipitation of the secondary α phase is closely related to heat treatment parameters—the volume fraction and size of the secondary α phase increase when increasing the solution temperature or aging time. At the same solution temperature and aging time, the secondary α phase became coarser, and the fraction decreased with increasing aging temperature. When Ti-35421 alloy was solution-treated at the α + β region for 1 h with aging surpassing 8 h, the tensile strength, yield strength, elongation and reduction of the area were achieved in a range of 1172.7–1459.0 MPa, 1135.1–1355.5 MPa, 5.2–11.8%, and 7.5–32.5%, respectively. The novel low-cost Ti-35421 alloy maintains mechanical properties and reduces the cost of materials compared with Ti-3Al-5Mo-5V-4Cr-2Zr (Ti-B19) alloy.

Download Full-text

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

MATEC Web of Conferences ◽

10.1051/matecconf/202032105003 ◽

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.

Download Full-text

Mechanical Behaviour of Beta Titanium Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1016.964 ◽

2021 ◽

Vol 1016 ◽

pp. 964-970

Author(s):

Nageswara Rao ◽

Geetha Manivasagam

Keyword(s):

Heat Treatment ◽

Titanium Alloys ◽

Dynamic Properties ◽

Solution Treatment ◽

Weight Ratio ◽

High Strength ◽

Static Properties ◽

Beta Titanium Alloy ◽

Beta Titanium ◽

Beta Titanium Alloys

Beta titanium alloys have several attractive features; this has resulted in this group of alloys receiving much attention since 1980’s. Among the attributes which distinguish them for their superiority over other structural materials are (i) high strength to which they can be heat treated, resulting in high strength to weight ratio (ii) high degree of hardenability which enables heat treatment in large section sizes to high strength levels (iii) excellent hot and cold workability, making them as competitive sheet materials etc. The standard heat treatment consists of solution treatment in beta or alpha plus beta phase field followed by aging. However, certain aging treatments can render the materials in a state of little or no ductility; the designer has to be aware of this behaviour and has to keep away from such treatments while working with the materials. Such unfavourable aging treatments may adversely affect not only the static properties such as reduction in area and elongation in a tensile test, but also dynamic properties such as impact toughness. Results of fractographic studies are in line with those of mechanical testing. The authors would present the foregoing analysis, based primarily on the wide-ranging researches they carried out on beta titanium alloy Ti15-3 and to some extent data published by researchers on other grades of beta titanium alloys. An attempt is made to explain the mechanisms underlying the embrittlement reactions that take place in beta titanium alloys under non-optimal aging treatments.

Download Full-text