Fatigue crack growth behavior and microstructural mechanisms in Ti-6Al-4V manufactured by laser engineered net shaping

Zhai, Yuanliang; Lados, Diana A.; Brown, Eric J.; Vigilante, Gregory N.

doi:10.1016/j.ijfatigue.2016.08.009

Cited by 122 publications

(57 citation statements)

References 24 publications

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“…The currently available crack growth data on AM Ti-6Al-4V has been limited to long cracks, however, fatigue cracks can exist as also physically-small cracks, and microstructurally-small cracks [56]. The difference lies on their crack length and width [57].…”

Section: Micro-mechanism Contributionmentioning

confidence: 99%

“…A long crack has a crack length and width much larger than the characteristic microstructural size scale. A physically-small crack once again has crack length and width larger than the characteristic microstructural size scale but has a crack length less than the equilibrium shield zone [region which is associated with crack closure effects [56,57]. Microstructurally-small cracks are those which have a crack length and width smaller than the shield zone and characteristic microstructural size scale.…”

Section: Micro-mechanism Contributionmentioning

confidence: 99%

“…The fatigue crack growth behaviour of all these cracks can be different. This is why it is important to improve our understanding of the fatigue crack growth behaviour of all types of cracks in the material, so as to develop a broader understanding of fatigue resistance capabilities of the material [56].…”

Section: Micro-mechanism Contributionmentioning

confidence: 99%

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A Review of the As-Built SLM Ti-6Al-4V Mechanical Properties towards Achieving Fatigue Resistant Designs

Agius

Kourousis

Wallbrink

2018

Metals

172

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Ti-6Al-4V has been widely used in both the biomedical and aerospace industry, due to its high strength, corrosion resistance, high fracture toughness and light weight. Additive manufacturing (AM) is an attractive method of Ti-6Al-4V parts' fabrication, as it provides a low waste alternative for complex geometries. With continued progress being made in SLM technology, the influence of build layers, grain boundaries and defects can be combined to improve further the design process and allow the fabrication of components with improved static and fatigue strength in critical loading directions. To initiate this possibility, the mechanical properties, including monotonic, low and high cycle fatigue and fracture mechanical behaviour, of machined as-built SLM Ti-6Al-4V, have been critically reviewed in order to inform the research community. The corresponding crystallographic phases, defects and layer orientations have been analysed to determine the influence of these features on the mechanical behaviour. This review paper intends to enhance our understanding of how these features can be manipulated and utilised to improve the fatigue resistance of components fabricated from Ti-6Al-4V using the SLM technology.

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Section: Micro-mechanism Contributionmentioning

confidence: 99%

Section: Micro-mechanism Contributionmentioning

confidence: 99%

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A Review of the As-Built SLM Ti-6Al-4V Mechanical Properties towards Achieving Fatigue Resistant Designs

Agius

Kourousis

Wallbrink

2018

Metals

172

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“…17,19 In both studies, the authors attributed the inferior fracture toughness in the as-built form to the fine and brittle acicular martensitic structure caused by rapid solidification of the material. In terms of the FCGR, the EBM Ti64 exhibited slower crack growth rates in the Paris law region than that in the wrought condition, in both orientations, 16 whereas FCGR in the SLM Ti64 in the as-built condition was faster in the lower ΔK region (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) and slower in the higher ΔK region (30-80 MPa√m) at load ratio of 0.1. 17 Similar trend was found by another study, 19 in which SLM Ti64 had slower FCGR than the wrought alloy in all three orientations at load ratio 0.1.…”

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confidence: 99%

Fracture toughness and fatigue crack growth rate properties in wire + arc additive manufactured Ti‐6Al‐4V

Zhang

Martina

Ding

et al. 2016

Fatigue Fract Eng Mat Struct

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A B S T R A C T This paper presents an experimental investigation of the fracture and fatigue crack growth properties of Ti-6Al-4V produced by the Wire + Arc Additive Manufacture (WAAM®) process. First, fracture toughness was measured for two different orientations with respect to the build direction; the effect of wire oxygen content and build strategy were also evaluated in the light of microstructure examination. Second, fatigue crack growth rates were measured for fully additive manufactured samples, as well as for samples containing an interface between WAAM® and wrought materials. The latter category covers five different scenarios of crack location and orientation with respect to the interface. Fatigue crack growth rates are compared with that of the wrought or WAAM® alone conditions. Crack growth trajectory of these tests is discussed in relation to the microstructure characteristics.Keywords fatigue crack growth; fracture toughness; microstructure; titanium; wire + arc additive manufacture. N O M E N C L A T U R Ea = Crack length B = Compact tension specimen thickness K IC = Plane-strain fracture toughness K Q = Conditional fracture toughness value P max = Applied load at fracture P Q = Conditional load value at fracture determined by ASTM Standard W = Compact tension specimen width σ ys = Material yield strength under tension load I N T R O D U C T I O NTitanium alloy Ti-6Al-4V (Ti64) has been used in the aerospace and other industries owing to its high specific strength, excellent resistance to fatigue and corrosion, and good performance at elevated temperature. With the increasing use of carbon fibre polymer composites in the airframes, titanium will be increasingly used because of its good compatibility with this material. However, titanium alloys are extremely expensive and very difficult to machine, if compared with other aerospace alloys such as aluminium. Therefore, using the Additive Manufacture (AM) technology to build titanium parts has become very attractive owing to the significant reduction in material waste, machining and tooling cost, manufacturing energy and time to market. Conventional powder bed AM also makes it possible to easily produce complicated parts. However, the cost of material powder is usually particularly high, which affects the overall cost of the process. This drawback is counterbalanced by the reduced material waste. Studies have shown that AM can be an economically and environmentally superior option to the traditional methods of machining from cast or forged billets for production in small batches.

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“…These properties may be also brought by the TiC carbides, formed with titanium which is also a '-former element and which can be used as base element as in the wellknown Ti-6Al-4V [21] . Hf, which led to the high performance directionally solidified DS200-Hf alloy [22] and which may serve to configure microstructures and properties of some alloys [23,24] , allow obtaining script-like MC carbides especially stable at elevated temperature in term of both morphology and volume fraction [9][10][11][12] , whatever the base element among cobalt, nickel and iron.…”

Section: Introductionmentioning

confidence: 99%

Microstructures and hardness of as-cast {C, Ta or Ti or Hf of Zr}-containing Cr-rich Niobium-based alloys candidate for uses at elevated temperatures

Berthod¹

2018

TSE

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Four alloys based on niobium and containing about 33wt.%Cr, 0.4wt.C and, in atomic content equivalent to the carbon one, Ta, Ti, Hf or Zr, were elaborated by classical foundry under inert atmosphere. Their as-cast microstructures were characterized by X-ray diffraction, electron microscopy, energy dispersion spectrometry and while their room temperature hardness was specified by Vickers indentation. The microstructures are in the four cases composed of a dendritic Nb-based solid solution and of an interdendritic NbCr2 Laves phase. Despite the MC-former behavior of Ta, Ti, Hf and Zr usually observed in nickel or cobalt-based alloys, none of the four alloys contain MC carbides. Carbon is essentially visible as graphite flakes. These alloys are brittle at room temperature and hard to machine. Indentationshows that the Vickers hardness is very high, close to 1000HV10kg. Indentation lead to crack propagation through the niobium phase and the Laves areas. Obviously no niobium-based alloys microstructurally similar to high performance MC-strengthened nickel-based and cobalt-based can be expected. However the high temperature mechanical and chemical properties of these alloys remain to be investigated.

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Fatigue crack growth behavior and microstructural mechanisms in Ti-6Al-4V manufactured by laser engineered net shaping

Cited by 122 publications

References 24 publications

A Review of the As-Built SLM Ti-6Al-4V Mechanical Properties towards Achieving Fatigue Resistant Designs

A Review of the As-Built SLM Ti-6Al-4V Mechanical Properties towards Achieving Fatigue Resistant Designs

Fracture toughness and fatigue crack growth rate properties in wire + arc additive manufactured Ti‐6Al‐4V

Microstructures and hardness of as-cast {C, Ta or Ti or Hf of Zr}-containing Cr-rich Niobium-based alloys candidate for uses at elevated temperatures

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