Tensile and High Cycle Fatigue Properties of a Minor Boron-Modified Ti&amp;ndash;22Al&amp;ndash;11Nb&amp;ndash;2Mo&amp;ndash;1Fe Alloy

Hagiwara, Masatoshi; Kitaura, Tomoyuki; Ono, Yumie; Yuri, Tetsumi; Ogata, Tsutomu; Emura, Satoshi

doi:10.2320/matertrans.m2012043

Cited by 9 publications

(17 citation statements)

References 24 publications

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“…6), and accordingly, it was found that the addition of 0.1 mass% B had no effect on VHCF behavior. However, contrary to these results, the authors have previously reported that the HCF strength of 0.1 mass% B-modified Ti6Al4V alloy 17) and Ti22Al11Nb2Mo1Fe 18) at room temperature increased compared to the B-free counterparts. These results are shown in Fig.…”

Section: Hcf Propertiescontrasting

confidence: 58%

“…It is well documented in the literature 18) that when components and systems are operated at applied stresses well below the conventional fatigue limit of 10E+7 cycles, damage at the microstructural length scale accumulates, leading to subsequent fatigue failure in the very high-cycle fatigue (hereinafter abbreviated to VHCF) regime of 10E+6 to 10E+9 cycles. Such a failure in the VHCF regime is a serious issue, especially for the auto components such as spring coils, cylinder heads and engine blocks, where very low alternating or cyclic stresses operate constantly and the service life extends well into the VHCF regime.…”

Section: Introductionmentioning

confidence: 99%

“…811) One concern regarding B-modified titanium alloys is that the TiB formed in titanium could cause early initiation of fatigue crack, which would lead to the degradation of fatigue properties. However, Hagiwara et al demonstrated in 0.1 mass% B-modified Ti6Al4V 17) and Ti22Al11Nb2Mo1Fe alloys 18) that the fatigue cracks originated neither from the TiB/matrix interface nor from the TiB itself but rather from shear fractures across microstructural units such as colonies or spherical ¡ phases, and that these B-modified alloys exhibit considerably higher high-cycle fatigue (hereinafter abbreviated to HCF) strength than those of B-free alloys. The reduced colony size and the inhibitory effect of TiB against the expansion of the fatigue initiation area were thought to be responsible for the improved HCF properties of these two alloys with lamellar and equiaxed microstructures, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Very High-Cycle Fatigue and High-Cycle Fatigue of Minor Boron-Modified Ti–6Al–4V Alloy

et al. 2019

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A refined fully lamellar microstructure with a prior ¢ grain size of ³100 µm was obtained for a 0.1 mass percent (%) B-modified Ti6Al 4V alloy. On the other hand, there were no morphological differences in equiaxed microstructures between the B-free and B-modified alloys; both had ¡ grain sizes of about 8 µm.The very high-cycle fatigue (VHCF) lifetimes in the regime from 10E+6 to 10E+10 cycles were measured for these microstructures by using hourglass-shaped specimens and an ultrasonic fatigue test machine at a frequency of 20 kHz, while high-cycle fatigue (HCF) lifetimes in the regime from 10E+4 to 10E+7 cycles were measured using smooth cylindrical specimens and a hydraulic servo fatigue test machine at 10 Hz and a fatigue ratio R of 0.1. The VHCF and HCF behaviors of B-modified alloys were found to be highly dependent on both microstructures and the level of applied stress. In the VHCF regime, where applied stress is well below the conventional fatigue threshold, the B-free and B-modified alloys exhibited the same fatigue strength, in other words, the same fatigue lifetime within the same microstructure. A set of fatigue lifetime data for B-free and B-modified alloys with equiaxed microstructures indicated that these alloys had higher fatigue strength than the alloys with lamellar microstructures in the VHCF diagram in the whole cycle range of up to 10E+10 cycles. The overall trend in the HCF lifetime or strength was that the addition of 0.1 mass% B had either a favorable effect or no influence on the fatigue life, depending on the level of applied stress. Above a certain level, which corresponded to a cycle regime up to about 10E+6 cycles for a lamellar microstructure and up to about 10E+7 cycles for an equiaxed microstructure, the fatigue lifetime was remarkably prolonged by the addition of 0.1 mass% B. However, in the regime beyond these cycles, when the stress level decreased, the favorable effect of B was gradually diminished and the HCF lifetime of the B-free and 0.1 mass% B-modified alloys were coincident in both lamellar and equiaxed microstructures; this coincidence was maintained thereafter. The mechanism for the dependence of the VHCF and HCF strength of the B-modified alloy on microstructures and the level of applied stress is proposed and discussed. [

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Section: Hcf Propertiescontrasting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Very High-Cycle Fatigue and High-Cycle Fatigue of Minor Boron-Modified Ti–6Al–4V Alloy

et al. 2019

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“…showed that the prior ¢-grain sizes of as-cast Ti6Al4V and Ti6Al2Sn4Zr2Mo0.1Si are reduced by about an order of magnitude from 1200 to 200 µm by the addition of 0.1 pct B. 18) Since then, it has been reported that grain-refined B-modified Ti6Al4V, 1834) Ti6Al2.75Sn4Zr0.4Mo 0.45Si (Ti-1100), 35) ¢-type Ti, 3638) Ti22Al11Nb2Mo 1Fe 39) and £ -TiAl 16) exhibited significant improvement in strength, stiffness, fatigue resistance and fracture toughness. By referring to those positive results, we tried to add a minor amount of B (0.1 mass pct) to the three derivative alloys and the baseline Ti27.5Al13Nb alloy.…”

Section: Introductionmentioning

confidence: 99%

Microstructure, Tensile and Creep Properties of Minor B-Modified Orthorhombic-Type Ti–27.5Al–13Nb Alloy and Its Nb-Replaced Mo- and Fe-Containing Derivatives

2022

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Ti27.5Al13Nb is an intermetallic alloy that incorporates the orthorhombic Ti 2 AlNb phase (O phase) and the ¡ 2 phase, and was previously developed by the authors for high-temperature applications. The aim of the present study was to develop less expensive orthorhombic alloys. For this purpose, a portion of the cost-prohibitive Nb in this baseline Ti27.5Al13Nb alloy was replaced with an equivalent amount of Fe and/or Mo, yielding three new derivative alloys: Mo-replaced Ti27.5Al8.7Nb1Mo, Fe-replaced Ti27.5Al5.5Nb1Fe and (Mo and Fe)replaced Ti27.5Al4.9Nb1Mo0.5Fe. Further, a minor amount of B (boron), i.e., 0.1 pct B, was added to these derivative alloys and baseline alloy. The microstructures and corresponding tensile and creep properties were examined in four cases: B-free and B-modified alloys with fully lamellar microstructures, and B-free and B-modified alloys with duplex microstructures. With the addition of 0.1 pct B, the prior B2 grain size of each ingot was drastically reduced by about one order of magnitude, from 600³1000 µm for the B-free alloy to 100³250 µm, and thereby a refined fully lamellar microstructure was obtained. However, this high degree of grain refinement did not markedly improve ductility at room temperature. A duplex microstructure consisting of a globular ¡ 2 -phase and a lamellar microstructure led to the improved ductility and tensile strength. The addition of B exerts either a positive or negative effect on the creep properties depending on the compositions and microstructures, creep test temperature and applied stress. The Mo-replaced alloys had better creep properties than the baseline alloy, whereas creep properties of the Fe-replaced and (Mo and Fe)-replaced alloys were considerably inferior to those of the baseline alloy. Among the four alloys, the 0.1 pct B-modified Mo-replaced alloy with a duplex microstructure exhibited the highest ductility of 4.7 pct at room temperature and higher tensile strength up to 1073 K and better creep properties than the other two derivative alloys and the baseline alloy.

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“…Since then, new efforts have been directed towards property optimization of different O þB2 alloys with the objectives of optimizing strength, toughness and creep. Minor additions of boron (0.1 at%) improve significantly the resistance to HCF crack initiation [18]. Quaternary additions of Zr, Mo, Nb and Si have been attempted with beneficial effects [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Monotonic and low cycle fatigue behavior of an O+B2 alloy at high temperatures

Srinivasulu¹,

Ghosal²,

Singh³

et al. 2014

Materials Science and Engineering: A

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Tensile and High Cycle Fatigue Properties of a Minor Boron-Modified Ti–22Al–11Nb–2Mo–1Fe Alloy

Cited by 9 publications

References 24 publications

Very High-Cycle Fatigue and High-Cycle Fatigue of Minor Boron-Modified Ti–6Al–4V Alloy

Very High-Cycle Fatigue and High-Cycle Fatigue of Minor Boron-Modified Ti–6Al–4V Alloy

Microstructure, Tensile and Creep Properties of Minor B-Modified Orthorhombic-Type Ti–27.5Al–13Nb Alloy and Its Nb-Replaced Mo- and Fe-Containing Derivatives

Monotonic and low cycle fatigue behavior of an O+B2 alloy at high temperatures

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