Fracture characteristics and microstructural factors in single and duplex annealed Ti–4.5Al–3V–2Mo–2Fe

Gunawarman, B.; Niinomi, Mitsuo; Fukunaga, Kei Ichi; Eylon, D.; Fujishiro, S.; Ouchi, Chiaki

doi:10.1016/s0921-5093(00)01986-9

Cited by 26 publications

(15 citation statements)

References 10 publications

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“…XRD analysis was conducted on the longitudinal direction of the specimens using Cu-K a line (lϭ0.15406 nm) under the conditions of voltage and current of 40 kV and 30mA, respectively. Microstructural parameters of primary a, prior b and secondary phases, which were reported completely in separate articles 11,12) showed that volume fraction of primary b phase decreases and volume fraction of prior b phase increases with increasing solution treatment temperature. Prior b grain size increases and grain size of primary a phase is nearly constant with increasing solution treatment temperature.…”

Section: Microstructural Observationsmentioning

confidence: 95%

“…It has been reported that the fine and local acicular a phase cannot deflect a crack and thus cannot increase the fracture toughness. 11,12) In the case of Ti-6Al-4V, it was reported that the low dynamic fracture toughness of this alloy is obtained when the microstructure having b phase with lattice parameter of 0.3239 nm. 7) This indicates that the low dynamic fracture observed in Ti-6Al-4V may also related to the intermediate stability of the b phase.…”

Section: Effect Of Stability Of Bmentioning

confidence: 98%

“…For b-rich aϩb type Ti-4.5Al-3V-2Mo-2Fe alloy, it was found that the fracture toughness, either K IC 10) or J IC , 11) has relatively low value when the alloy is air-cooled from solution treatment temperature of 1123 K. From the viewpoint of the fracture mechanisms, it has been explained that the reasons for the low fracture toughness are decreasing the effects of crack tip blunting and crack deflection due to the presence of fine 11) and local 12) acicular a phase in matrix b phase. Ishikawa et al 13) have reported that the relatively higher amount of retained b phase is obtained when the alloy is water-cooled or air-cooled from the solution treatment temperature at 1123 K. The high content of the "soft" retained b phase may cause the relatively higher damping capacity of the alloy water-quenched from 1123 K as reported by Guan et al 14) This factor may also contribute to the low fracture toughness of the alloy air-cooled from 1123 K. Since retained b phase is well known to have low stability and has a potential to transform to DIM, it is necessary, therefore, to investigate the stability of b phase and its relationship with mechanical properties of the alloy.…”

Section: Introductionmentioning

confidence: 99%

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Effect of .BETA. Phase Stability at Room Temperature on Mechanical Properties in .BETA.-Rich .ALPHA.+.BETA. Type Ti-4.5Al-3V-2Mo-2Fe Alloy.

et al. 2002

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The stability of the b phase at room temperature in various microstructures of a b-rich aϩb type Ti-4.5Al-3V-2Mo-2Fe alloy and its relationship with the fracture toughness, hardness and tensile properties were investigated. A variety of microstructures were established by varying solution treatment temperatures in aϩb field, cooling rate after solution treatment and the condition of subsequent second-step annealing treatment after air-cooling treatment. These microstructures have b phase with lattice parameters of b phase ranging between 0.3244 nm and 0.3221 nm. The stability of b phase, which is indicated by decreasing lattice parameter of b phase, is increased by either lowering cooling rate or formation of diffusional transformation products (secondary phases) in the b phase. The b phase with lattice parameter of b phase around 0.3242 nm is the minimal instability of unstable b phase at room temperature for attaining deformation-induced martensite in tensile specimens. There exists a proper degree of b phase stability for increasing the fracture toughness, J IC . The relatively higher fracture toughness is obtained at low or high stability of b phase. The high fracture toughness at low stability of b phase (unstable b) is mainly due to the deformation-induced martensite. While, the high fracture toughness at high stability of b phase (stable b) is mainly due to the secondary phase in the b phase that produces a prominent crack deflection toughening mechanism. However, the relatively lower fracture toughness is obtained at high stability of b phase when the b phase contains small amount or no secondary phase. This leads to conclude that, if only the b phase stability is taken into account for explaining fracture mechanism, the fracture toughness would decrease monotonously with increasing stability of b phase. The Vickers hardness is nearly independent of stability of b phase.KEY WORDS: mechanical properties; fracture toughness; hardness; tensile properties; stability of b phase; microstructure; b-rich aϩb titanium alloy; Ti-4.5Al-3V-2Mo-2Fe.

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Section: Microstructural Observationsmentioning

confidence: 95%

Section: Effect Of Stability Of Bmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Effect of .BETA. Phase Stability at Room Temperature on Mechanical Properties in .BETA.-Rich .ALPHA.+.BETA. Type Ti-4.5Al-3V-2Mo-2Fe Alloy.

et al. 2002

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“…4,5) High fracture toughness of Ti-4.5Al-3V-2Fe-2Mo (-stabilized þ alloy) has been found to be associated with coarsen acicular or plate-like structures. 6,7) Laser welding is a well-established process for the joining of metals with low heat input, and it has been used to weld titanium alloys extensively for various applications. 8,9) The fracture toughness of Ti-6A1-4V welds in the as-welded condition is shown to be superior to that of the þ processed parent metal.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Preheating on Notched Tensile Strength and Impact Toughness of Ti-6Al-6V-2Sn Laser Welds

2011

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Notched tensile strength (NTS) and impact toughness were determined for Ti-6Al-6V-2Sn laser welds subjected to post-weld heat treatment (PWHT) at distinct temperatures. In this study, the specimens were either preheated at 300 C or maintained at room temperature before laser welding. The preheated weld, associated with a reduced cooling rate, had obviously lower hardness than the non-preheated weld in the as-welded condition. After PWHT at 482 C for 3 h, the preheated weld also exhibited considerably lower hardness than the non-preheated weld. In general, preheating at 300 C could effectively increase the NTS and impact toughness of Ti-6Al-6V-2Sn laser welds. The preheated weld in the as-welded condition had superior NTS to other welds being tested. On the other hand, the welds after PWHT at 704 C possessed the best resistance to unstable impact fracture, regardless of preheating. Usually, the coarse þ structures together with intergranular were responsible for the high NTS and impact toughness of the weld.

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“…The high toughness of Ti-4.5Al-3V-2Fe-2Mo, which contains coarse acicular or plate-like structure, is associated with the increased micro-cracking and crack-branching during fracture toughness tests. 9,10) The morphology of primary also affects the fracture toughness of SP-700 alloy; for example, a low aspect ratio of primary decreases the ability to deform and leads to a low fracture toughness. 11) On the other hand, increasing prior grain size and coarsening acicular of Ti-4.5Al-3V-2Fe-2Mo result in an increased fracture toughness.…”

Section: Introductionmentioning

confidence: 99%

Influence of Microstructures on the Notched Tensile Strength of Ti-4.5Al-3V-2Fe-2Mo Alloy

et al. 2008

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The notched tensile strength (NTS) of Ti-4.5Al-3V-2Fe-2Mo specimens with distinct heat treatment conditions was investigated and correlated to microstructures. The specimens were solution-treated at either 980 or 870 C (above or below the -transus) and then waterquenched prior to aging treatments. After aging at 482, 593, and 704 C, titanium martensite ( 0 or 00 ) decomposed into and with distinct sizes. Additionally, the specimens aged at 482 C were particularly susceptible to notch brittleness, regardless of the solution temperature. As the aging temperature increased, the lower hardness associated with coarsened þ structures resulted in decreased notch brittleness of the alloy. In general, the specimens containing primary in microstructure were prone to brittle fracture and reduced NTS. The alignment of martensite packets (or needles) with respect to the crack growth direction could affect the fracture appearance of the specimens, particularly for the coarsegrained specimens which were solution-treated at 980 C. Furthermore, the existence of grain boundary for the specimens aged at 593 C or higher promoted grain boundary sliding during notched tensile tests.

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Fracture characteristics and microstructural factors in single and duplex annealed Ti–4.5Al–3V–2Mo–2Fe

Cited by 26 publications

References 10 publications

Effect of .BETA. Phase Stability at Room Temperature on Mechanical Properties in .BETA.-Rich .ALPHA.+.BETA. Type Ti-4.5Al-3V-2Mo-2Fe Alloy.

Effect of .BETA. Phase Stability at Room Temperature on Mechanical Properties in .BETA.-Rich .ALPHA.+.BETA. Type Ti-4.5Al-3V-2Mo-2Fe Alloy.

The Effect of Preheating on Notched Tensile Strength and Impact Toughness of Ti-6Al-6V-2Sn Laser Welds

Influence of Microstructures on the Notched Tensile Strength of Ti-4.5Al-3V-2Fe-2Mo Alloy

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