Fatigue Performance of the Novel Titanium Alloy Timetal 407

Davey, W.G.; Bache, M.R.; Davies, Helen; Thomas, Matthew

doi:10.1051/matecconf/201816504001

Cited by 8 publications

(11 citation statements)

References 10 publications

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“…The chemical compositions of the three titanium alloys [20,21] are given in analysis [22]. When the long striker is used, the incident and reflected waves superimpose.…”

Section: Introductionmentioning

confidence: 99%

Rate dependent behaviour and dynamic strain localisation of three novel impact resilient titanium alloys: Experiments and modelling

Zhang

Gour

Petrinić

et al. 2020

Materials Science and Engineering: A

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The tensile behaviour of three ductile titanium alloys, Ti0.7Al4V, Ti1Al4V and Ti3Al2.5V, conceived for impact containment applications, is characterized at quasi-static, intermediate and high strain rates. Tests have been performed using a screw driven mechanical system and a bespoke in-house developed split Hopkinson tension bar equipped with ultra-high speed photographic equipment 1. The three alloys present noticeable strain rate sensitivity. Ti1Al4V is characterised by the lowest flow stress and highest ductility of the three alloys. Ti3Al2.5V higher flow stress but lowest strain to failure while Ti0.7Al4V has similar flow stress but larger engineering failure strain compared to Ti3Al2.5V. The dynamic true strain rate, determined by measuring the time history of the minimum cross-section diameter during necking, reaches values up to one order of magnitude higher than the nominal strain rate. This phenomenon, occurring during dynamic strain localisation, is of fundamental importance for understanding and modelling the dynamic behaviour of ductile alloys designed to withstand impact loading. The experimental results are used to determine the material parameters of the Johnson-Cook (JC) and Khan-Huang-Liang (KHL) models, which are incorporated in the ABAQUS/explicit code for finite element simulations of the dynamic tensile tests. It is found that the KHL model predicts the experimentally measured strain field, deformed geometry, effective strain rate and macroscopic force-displacement response during the high strain rate experiments with significantly better agreement than the JC model.

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“…The chemical compositions of the three titanium alloys [20,21] are given in analysis [22]. When the long striker is used, the incident and reflected waves superimpose.…”

Section: Introductionmentioning

confidence: 99%

Rate dependent behaviour and dynamic strain localisation of three novel impact resilient titanium alloys: Experiments and modelling

Zhang

Gour

Petrinić

et al. 2020

Materials Science and Engineering: A

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“…In conclusion, the novel α + β titanium alloy Ti-407 has shown good HCF strength, relative to yield properties, and provided better HCF strength compared to previous forms of Ti-6-4 assessed by this laboratory [27], without compromising ductility, machinability and manufacturing properties. The relatively high HCF strength of Ti-407 can be viewed as an encouraging outcome for what is recognised as a comparatively low static strength alloy.…”

Section: Discussionmentioning

confidence: 75%

Microstructural Control of Fatigue Behaviour in a Novel α + β Titanium Alloy

Bache

Davies

Davey

et al. 2019

Metals

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The novel titanium alloy TIMETAL® 407 (Ti-407) has been developed as an alternative to Ti-6Al-4V (Ti-6-4), for applications that demand relatively high ductility and energy absorption. Demonstrating a combination of lower strength and greater ductility, the alloy introduces a variety of cost reduction opportunities, including improved machinability. Thermo-mechanical processing and its effects on microstructure and subsequent mechanical performance are characterised, including a detailed assessment of the fatigue and crack propagation properties. Demonstrating relatively strong behaviour under high-cycle fatigue loading, Ti-407 is nevertheless susceptible to time-dependent fatigue effects. Its sensitivity to dwell loading is quantified, and the associated deformation and fracture mechanisms responsible for controlling fatigue life are explored. The intimate relationship between thermo-mechanical processing, micro-texture and fatigue crack initiation through the generation of quasi-cleavage facets is highlighted. Consistent fatigue crack growth kinetics are demonstrated, independent of local microstructure.

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“…The rate and magnitude of strain accumulation during load-controlled dwell fatigue experiments have been shown to exceed that achieved under fast cycles [25] and is consistent with the time dependency inherent in the dislocation Dwell fatigue failures in α/β and near α titanium alloys are often (but not exclusively) reported to initiate at sub-surface sites. In contrast with classical fatigue crack initiation models [26] both low and high cycle fatigue failures in these alloy variants have also been reported to initiate sub-surface [27,28]. The quasi-cleavage facet mechanism relies on the probabilistic distribution of weak and strong grains in juxtaposition to each other.…”

Section: Discussionmentioning

confidence: 86%

“…Invoking the Stroh model [14], Evans and Bache previously promoted this process to explain the formation of quasi-cleavage facets, reliant on time dependent planar slip, dislocation pile up and progressive opening of a facet on the basal plane of the neighbouring "strong" grain [15]. Subsequent studies of finer grained near α and α/β variants containing MTRs has recently led to a modification of the Evans-Bache model to account for highly textured microstructures on a regional scale [16].…”

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confidence: 99%

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Novel Experimentation for the Validation of Mechanistic Models to Describe Cold Dwell Sensitivity in Titanium Alloys

Sackett

Bache

2021

Metals

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Previous mechanistic models, proposed to explain the process of damage accumulation and stress redistribution between strong and weak regions inherent within the microstructure of α/β and near α titanium alloys, are validated through a matrix of experiments employing a non-standard variant of the alloy Ti 685. The grain size of the model material was deliberately processed to offer grains up to 20 mm in diameter, to facilitate constitutive measurements within individual grains. A range of experiments were performed under static and cyclic loading, with the fatigue cycle conducted under either strain or load control. Data will be reported to demonstrate significant variations in elastic and plastic properties between grains and emphasise the role of time dependent strain accumulation. Implications for the “dwell sensitive fatigue” or “cold creep” response of conventional titanium alloys will be discussed.

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Fatigue Performance of the Novel Titanium Alloy Timetal 407

Cited by 8 publications

References 10 publications

Rate dependent behaviour and dynamic strain localisation of three novel impact resilient titanium alloys: Experiments and modelling

Rate dependent behaviour and dynamic strain localisation of three novel impact resilient titanium alloys: Experiments and modelling

Microstructural Control of Fatigue Behaviour in a Novel α + β Titanium Alloy

Novel Experimentation for the Validation of Mechanistic Models to Describe Cold Dwell Sensitivity in Titanium Alloys

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