Initiation and propagation of short fatigue cracks in forged Ti6Al4V

Knobbe, Helge; Köster, Philipp; Christ, Hans‐Jürgen; Fritzen, Claus‐Peter; Riedler, Martin

doi:10.1016/j.proeng.2010.03.101

Cited by 52 publications

(29 citation statements)

References 17 publications

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“…In fact, this effect (linked to the creation of surface compressive stresses) suppresses the propagation of surface-initiated cracks to the subsurface [43,47]. In the event that a surface crack progresses to the interior, it can otherwise cross grain boundaries unhindered, by changing from one slip system to another according to the new grain orientation [48]. Despite these beneficial effects, when strains are too high the mismatch in Young's moduli, E, between the substrate and the nitride layer (as reported in Table 3) may lead to early crack formation in the brittle nitride case [47].…”

Section: Rotating-bending Fatigue Testingmentioning

confidence: 99%

Evaluating the effects of PIRAC nitrogen-diffusion treatments on the mechanical performance of Ti–6Al–4V alloy

Bonello

Wilson

Housden

et al. 2014

Materials Science and Engineering: A

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a b s t r a c tPowder Immersion Reaction Assisted Coating (PIRAC) is a relatively simple nitrogen diffusion based process which has been proposed as a technique capable of considerable improvements in the tribological performance of ceramics and metals alike; however, the necessary exposure of the substrate material to high temperatures for several hours may have an adverse effect on the bulk properties of materials such as titanium alloys. The effect of PIRAC treatments on the bulk metallography and mechanical properties of Ti-6Al-4V has been studied. Following PIRAC nitrogen-diffusion treatment, studies using X-ray diffraction and cross-sectional microscopy have shown evidence of the formation of a thin ( $ 1.4 mm) TiN/Ti 2 N layer, together with the presence of some Ti 3 Al intermetallic phase. Semilogarithmic S-N plots show a deleterious effect after PIRAC treatment in terms of material cyclic fatigue strength, particularly at higher treatment temperatures. Samples processed at 800 1C for 4 h however exhibit better fatigue performance than others treated at lower temperatures for longer nitriding times. Fractographic inspection has shown that fatigue cracks originate at (or near) the surface for the untreated Ti-alloy and from the subsurface regions following diffusion treatment, owing to the build-up of compressive stresses in the latter, which hinder crack propagation.

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Section: Rotating-bending Fatigue Testingmentioning

confidence: 99%

Evaluating the effects of PIRAC nitrogen-diffusion treatments on the mechanical performance of Ti–6Al–4V alloy

Bonello

Wilson

Housden

et al. 2014

Materials Science and Engineering: A

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“…), titanium components (particularly Ti-6Al-4V) are often used for manufacturing critical systems such as airfoils, undercarriage components, and airframes [1][2][3][4] instead of heavy steel components. During these applications titanium structures are often exposed to fatigue loading [1].…”

Section: Introductionmentioning

confidence: 99%

“…Depending on the thermomechanical treatment or heat treatment of the (α + β) titanium alloy, such as Ti-6Al-4V, the microstructure and mechanical properties can vary in a wide range [3,6]. Such influences have been documented in numerous reports in the literature [4,[7][8][9][10][11]. However, due to experimentation limitations, experimental results are not always reproducible, and thus it is difficult to compare among fatigue properties obtained from different tests, even for a same microstructure.…”

Section: Introductionmentioning

confidence: 99%

Effect of microstructure on the fatigue properties of Ti–6Al–4V titanium alloys

Shi

Sha

et al. 2013

Materials & Design (1980-2015)

178

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Publisher rights This is the author's version of a work that was accepted for publication in Materials & Design. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Materials & Design, Vol. 46, 04/2013 General rights Copyright for the publications made accessible via the Queen's University Belfast Research Portal is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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“…36 The explanation of the presence of markings on facets in these experiments, and the absence of these markings in similar publications, 3,7,8,10,11,17,20 can be sought in the crystallographic texture of the alpha phase, which is different for the wire-drawn samples in this study compared to the forged rods used in other studies. It has been reported that facets are parallel to certain crystallographic planes, in most cases the basal plane 7,12,27,32,37,38 or the prismatic plane, 7,27 which means that the spatial angles of the facet planes are linked to the texture. The alpha phase texture of the wire used in this study is shown in Figure 8.…”

Section: Experimental Methodsmentioning

confidence: 99%

Internal fatigue crack initiation in drawn Ti–6Al–4V wires

Everaerts

Verlinden

Wevers

2016

Materials Science and Technology

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Fatigue cracks in titanium alloys are often found to initiate at faceted alpha grains. In the very high cycle fatigue regime, crack initiation tends to shift from the surface towards the interior of the material, and more initiation facets can be found on the fracture surface. In this study, fatigue tests were performed on drawn and heat-treated Ti-6Al-4V wires. Only a few samples fractured due to interior initiation. The facets at the initiation sites of these samples were not flat, but had markings on the nano-scale, and were highly inclined. A possible explanation for these aspects is the crystallographic texture of the wire, and a reflection is made on the suggested mechanisms of facet formation.

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Initiation and propagation of short fatigue cracks in forged Ti6Al4V

Cited by 52 publications

References 17 publications

Evaluating the effects of PIRAC nitrogen-diffusion treatments on the mechanical performance of Ti–6Al–4V alloy

Evaluating the effects of PIRAC nitrogen-diffusion treatments on the mechanical performance of Ti–6Al–4V alloy

Effect of microstructure on the fatigue properties of Ti–6Al–4V titanium alloys

Internal fatigue crack initiation in drawn Ti–6Al–4V wires

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