Low ΔK faceted crack growth in titanium alloys

Pilchak, Adam L.; Bhattacharjee, Anup Kumar; Rosenberger, A. H.; Williams, James C.

doi:10.1016/j.ijfatigue.2008.03.036

Cited by 69 publications

(64 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The grains fracture near the (0002) plane, which has been documented [24,22,20]. The misorientation is reported to be smaller in facets formed by continuous cycling than dwell facets, but the difference in misorien-325 tation found here was too small for a clear distinction between the load regimes.…”

supporting

confidence: 51%

Influence of complex LCF and dwell load regimes on fatigue of Ti–6Al–4V

et al. 2016

View full text Add to dashboard Cite

Real components are usually subjected to variable amplitude fatigue, and yet the deformation micromechanisms that occur due to such load changes have barely been the subject of study. Here, unidirectionally rolled equiaxed Ti6Al-4V plate was subjected to mixed dwell and variable amplitude low cycle fatigue (LCF), with the finding that overloads near the yield stress were found to retard subsequent fatigue crack growth, whilst elastic underloads were found to accelerate subsequent growth. Dwell intervals were found to be especially damaging, to a far greater extent than either dwell or LCF alone. Dwell facets were found to initiate subsurface and to be smoother than LCF facets, but were otherwise similar in orientation (∼ 30 • to the loading axis) and crystallographic plane, 2-13 • from (0002). However, no alteration of the slip bands underlying striations was observed at the point of load changes using TEM. In failure investigation, striation counting is an important tool; the loading changes used were not found to affect the number of striations formed. Dislocation networks were found between similarly oriented grains in the as-received material, which disintegrated under dwell loading and at high stresses.

show abstract

supporting

confidence: 51%

Influence of complex LCF and dwell load regimes on fatigue of Ti–6Al–4V

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Moreover, crack propagation occurs on or near basal planes [20] at small-crack lengths, so tilt boundaries offer resistance to crack propagation through deflection of the crack path and the development of roughness-induced closure. Basal twist boundaries, on the other hand, offer no such similar resistance to small fatigue-crack growth as evidenced by previous marker band studies [21].…”

Section: Microscopymentioning

confidence: 68%

A dataset for the development, verification, and validation of microstructure-sensitive process models for near-alpha titanium alloys

Pilchak

Shank²,

Tucker

et al. 2016

Integr Mater Manuf Innov

View full text Add to dashboard Cite

Near-alpha titanium alloys are used for moderate-temperature applications in the early stages of the compressor in gas turbine engines. The quasi-static and fatigue properties of these alloys depend heavily on microstructure due to the absence of hard second phases and inclusions which can nucleate voids or cracks. Moreover, these alloys are known to exhibit a significant reduction in fatigue life when subjected to high mean stress or upon the application of dwell-fatigue cycles. Previous analysis has elucidated the microstructural features that drive these properties; the most important features are the volume fraction, size, and shape of clusters of similarly oriented alpha particles or microtextured regions (MTRs). To date, there have been few efforts to elucidate in a quantitative fashion the evolution of MTRs during thermomechanical processing (TMP). To meet this need, we have performed hot-compression tests on Ti-6Al-2Sn-4Zr-2Mo-0.1Si billet material with high-aspect-ratio MTRs at 0°, 45°, and 90°to the direction of primary metal flow during manufacture (i.e., the billet axis), thoroughly characterized the initial and final microstructures, and quantified field variables via finite-element method (FEM) process simulations for each experiment. These data can be used for a variety of purposes including the development, verification, and validation of models for microstructure/texture/microtexture evolution and defect formation.

show abstract

“…Pilchak et al [141] addressed non-dwell facet growth in Ti-6Al-4V with large colonies and observed facets growing along basal planes, finding that many thousands of cycles can contribute to the creation of a facet inclined close to 45 • to the loading axis. Crack growth occurred over differently oriented α lamellae if the colonies shared a common basal plane orientation.…”

Section: (C) Cold Dwell Facet Nucleation Fatigue and Crack Growth Inmentioning

confidence: 99%

On the mechanistic basis of deformation at the microscale in hexagonal close-packed metals

2015

View full text Add to dashboard Cite

This is an overview of micromechanical deformation mechanisms in hexagonal close-packed metals. We start with an in-depth discussion of single-crystal behaviour concerning crystallographic slip, plastic anisotropy and deformation twinning. We move on to discuss some complexities involved in polycrystalline deformation and modelling approaches, focusing on rate effects in titanium alloys that are thought to play a significant role in dwell fatigue. We finish our review with a brief commentary on current understanding and state-of-the-art techniques, and outline some key areas where further study is recommended.

show abstract

Low ΔK faceted crack growth in titanium alloys

Cited by 69 publications

References 30 publications

Influence of complex LCF and dwell load regimes on fatigue of Ti–6Al–4V

Influence of complex LCF and dwell load regimes on fatigue of Ti–6Al–4V

A dataset for the development, verification, and validation of microstructure-sensitive process models for near-alpha titanium alloys

On the mechanistic basis of deformation at the microscale in hexagonal close-packed metals

Contact Info

Product

Resources

About