Influence of thermal exposure on the tensile properties and microstructures of Ti60 titanium alloy

Jia, Weiju; Zeng, Weidong; Liu, Jianrong; Zhou, Yigang; Wang, Qingjiang

doi:10.1016/j.msea.2011.10.011

Cited by 59 publications

(19 citation statements)

References 15 publications

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“…Over the past 30 years, numerous studies have been carried out on the heat treatment or terminal exposure of these near α Ti alloys. It was reported that both α 2 phase and silicide have a great influence on the mechanical properties of near-α Ti alloy [10,11]. Jia et al [12] have summarized the effects of aging temperature and time on the tensile properties of Ti60 alloy.…”

Section: Introductionmentioning

confidence: 99%

Effects of heat treatments on microstructure and tensile properties of as-extruded TiBw/near-α Ti composites

Wang

Huang

et al. 2015

Materials & Design

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Section: Introductionmentioning

confidence: 99%

Effects of heat treatments on microstructure and tensile properties of as-extruded TiBw/near-α Ti composites

Wang

Huang

et al. 2015

Materials & Design

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“…The model developed in the present work allows calculating the kinetics of oxygen ingress in the system. Oxygen is a source of embrittlement for the HCP ␣ Zr phase [6,[25][26][27][28], as it is the case for titanium-base alloys with the ␣ Ti phase [29]. In the present case, when the sample is cooled down from the high temperature, it is composed of an external ␣ Zr layer which was enriched in oxygen at high temperature, and an inner ␣ Zr layer which was formed during cooling by transformation of the prior-␤ Zr phase.…”

Section: Samplesmentioning

confidence: 98%

Experimental study and numerical simulation of high temperature (1100–1250 °C) oxidation of prior-oxidized zirconium alloy

et al. 2016

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Previous experiments showed that the thickness of a thick prior-oxide layer formed on Zircaloy-4 fuel cladding can decrease during the first seconds at very high-temperature, before re-growing. We confirmed these results with oxidations performed at 1200 • C on prior-oxidized Zircaloy-4. The initial reduction of the prior-oxide was explained by the balance of the oxygen fluxes at the metal/oxide interface and successfully reproduced by numerical simulations using a diffusion-reaction model. Different hypotheses were considered for the diffusion coefficients of oxygen in the different layers. This allowed discussing the effect of the prior-oxidation on the kinetics of oxygen embrittlement of the metallic substrate. Abbreviations: ␣ red , ␣Zr(O) phase formed by reduction of the low temperature oxide layer; Exp, experimental, i.e. data link with experimental results; EKINOX-Zr, Estimation KINetics OXidation numerical model for Zr alloys; HCP, hexagonal close-packed; HT, high temperature; HTox/HT ZrO2, oxide layer formed at high temperature (T ≥ 1000 • C); LOCA, loss-of-coolant-accident; LT, Low temperature, i.e. the in-service temperature of the PWR (T≈320 • C); LTox/LT ZrO2, oxide layer formed at low temperature; Num., numerical, i.e. data link to numerical results; PBR, Pilling-Bedworth ratio; Prior-␤Zr, phase formed from the cooling of ␤Zr phase stable at high temperature; PWR, pressurized-light-water-reactor.

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“…However, as any other intermetallic phases, α 2 is brittle and can cause reduction in ductility. It is reported that mobile dislocations are able to shear α 2 precipitates during tensile deformation; leading to a reduction in the local resolved shear stress on active slip planes [27]. However dislocation mobility is retarded on other (not activated) planes leading to planar slip and cause dislocation pile ups against grain boundaries in titanium alloys [28].…”

Section: The Effect Of Ti 3 Al (α 2 ) Precipitates On Ductility In Timentioning

confidence: 99%

“…However dislocation mobility is retarded on other (not activated) planes leading to planar slip and cause dislocation pile ups against grain boundaries in titanium alloys [28]. Thus, it is generally believed that α 2 phase is anisotropic, prone to localisation of slip and poor ductility [27] precipitates solvus temperatures were calculated using JMatPro programme. As shown in Figure 10, the solvus temperature of α 2 phase and silicide in Ti-834 were determined to be 675ºC and 1050ºC, respectively.…”

Section: The Effect Of Ti 3 Al (α 2 ) Precipitates On Ductility In Timentioning

confidence: 99%

The hierarchy of microstructure parameters affecting the tensile ductility in centrifugally cast and forged Ti-834 alloy during high temperature exposure in air

et al. 2016

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Ductility regression is the main concern in using Ti-834 titanium alloy at temperatures above 500ºC for aerospace applications. The reduction of ductility in titanium alloys at high temperatures is strongly correlated to the exposure time. In the current study the effect of prolonged exposure at 500 o C on the tensile ductility of two differently processed Ti-834 alloys was investigated. In order to simulate actual Ti-834 processing routes, forged and centrifugally cast materials were used. The tensile tests were conducted on various specimens exposed at 500ºC for 100, 200 and 500 hours to observe microstructure feature changes. Moreover, the effect of microstructure, microtexture, αcase, α 2 and silicide precipitate coarsening during high temperature exposure was studied thoroughly. The cast alloy was found to have a minimum ductility and failed at 1.8% strain after exposure at 500 o C/500 hour when the α-case layer was retained during testing, whilst, the ductility of the forged alloy was unaffected. The effects of individual microstructural parameters on the ductility regression in Ti-834 alloy were quantified. The results showed that 7.1% strain differences between the cast and forged alloy are related to microstructural variations including; morphology, lath widths, grain size and shape, grain orientations and microtexture. A total of 9.6 % strain loss 2 was observed in centrifugally cast Ti-834 after aging at 500ºC/500h and quantified as follow; 3.6% due to α-case formation during high temperature exposure, 0.2% due to α 2-precipitates coarsening, 4.4% due to further silicide formation and coarsening, 1.4% due to additional microstructure changes during high temperature exposure. Furthermore, silicide coarsening on α/β phase boundaries caused large void formation around the precipitates. A theoretical model supported by experimental observations for silicide precipitation in fully colony and duplex microstructures was established. The element partitioning during exposure caused Al and Ti depletion in the vicinity of the β phase in the lamellae, i.e., α s area. This resulted in lowering the strength of the alloy and facilitated the formation of Ti 3 (SiZr) 2 precipitates. The Al depletion and nano-scale partitioning observed at the α s /β boundaries resulted in easy crack initiation and promoted propagation in the centrifugally cast colony microstructure and reduced the basal slip τ crss. Furthermore, silicides were not formed in α p (high Al, Ti and low Zr areas) in the forged duplex microstructure that promoted superior mechanical performance and ductility over the cast alloy.

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Influence of thermal exposure on the tensile properties and microstructures of Ti60 titanium alloy

Cited by 59 publications

References 15 publications

Effects of heat treatments on microstructure and tensile properties of as-extruded TiBw/near-α Ti composites

Effects of heat treatments on microstructure and tensile properties of as-extruded TiBw/near-α Ti composites

Experimental study and numerical simulation of high temperature (1100–1250 °C) oxidation of prior-oxidized zirconium alloy

The hierarchy of microstructure parameters affecting the tensile ductility in centrifugally cast and forged Ti-834 alloy during high temperature exposure in air

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