In situ tailoring microstructure in additively manufactured Ti-6Al-4V for superior mechanical performance

Xu, Wei; Lui, Edward; Pateras, Aaron; Qian, Ma; Brandt, Milan

doi:10.1016/j.actamat.2016.12.027

Cited by 537 publications

(211 citation statements)

References 29 publications

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“…Moreover, the processing parameters that have been used for the fabrication of the test coupons are listed in Table 2. The improvement in elongation achieved with a lamellar (α + β) is evidenced in the results obtained by Xu et al [9] (Xu 1) and Xu et al [15] (Xu 2), which is presented in Figure 4. What is also observed in Figure 4 is the significant scatter in the results obtained from α' martensite coupons, suggesting that defects have an appreciable impact on the mechanical properties.…”

Section: Behaviour Under Tensionsupporting

confidence: 59%

“…• α martensite [1,4,6,8,20,26,32,[40][41][42][43][44][45]; • Coarse lamellar (α + β) [9,17]; • Ultrafine lamellar (α + β) [15,16].…”

Section: Behaviour Under Tensionmentioning

confidence: 99%

“…Further improvements efforts in the in situ transformation of α martensite have been achieved by Xu et al [9] towards overcoming the difficulties associated with the FOD adjustment and the high microstructure sensitivity to FOD. In their work, transformation was achieved by employing a scanning strategy which uses the residual heating of new layers on previous layers to maintain the temperature profile in order to ensure α martensite transformation into α + β.…”

Section: Introductionmentioning

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

171

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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: Behaviour Under Tensionsupporting

confidence: 59%

“…• α martensite [1,4,6,8,20,26,32,[40][41][42][43][44][45]; • Coarse lamellar (α + β) [9,17]; • Ultrafine lamellar (α + β) [15,16].…”

Section: Behaviour Under Tensionmentioning

confidence: 99%

Section: Introductionmentioning

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

171

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“…5 Recent developments have shown that SLM Ti6Al-4V in the as-built state can achieve a fully lamellar a + b microstructure via in situ martensite decomposition by manipulating SLM variables, including the focal off-set distance, energy density, inter-layer time and hatch spacing (the layer thickness was fixed at 60 lm). [7][8][9][10] In addition, tunable microstructural length scales and superior mechanical properties were achieved in SLM Ti-6Al-4V in the as-built state. These developments have made SLM of Ti-6Al-4V essentially similar to selective electron beam melting (SEBM) in terms of both the as-built microstructures and tensile properties.…”

Section: Introductionmentioning

confidence: 98%

New Development in Selective Laser Melting of Ti–6Al–4V: A Wider Processing Window for the Achievement of Fully Lamellar α + β Microstructures

Lui

Pateras

et al. 2017

JOM

Self Cite

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Recent progress has shown that Ti-6Al-4V fabricated by selective laser melting (SLM) can achieve a fully lamellar a + b microstructure using 60 lm layer thickness in the as-built state via in situ martensite decomposition by manipulating the processing parameters. The potential to broaden the processing window was explored in this study by increasing the layer thickness to the less commonly used 90 lm. Fully lamellar a + b microstructures were produced in the as-built state using inter-layer times in the range of 1-12 s. Microstructural features such as the a-lath thickness and morphology were sensitive to both build height and inter-layer time. The a-laths produced using the inter-layer time of 1 s were much coarser than those produced with the inter-layer time of 12 s. The fine fully lamellar a + b structure resulted in tensile ductility of 11% and yield strength of 980 MPa. The tensile properties can be further improved by minimizing the presence of process-induced defects.

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“…The second one, produced by the SLM method, is an α' martensitic-type structure, which is the consequence of diffusionless processes. Because α martensite contained in columnar prior-β grains is often linked to poor ductility and low toughness, some processing variables were investigated for martensite decomposition [64]. The Ti-6Al-4V microstructure after EBM is fine when compared to the conventional wrought Ti-6Al-4V [65].…”

Section: Microstructures Of the Ti-6al-4v Alloysmentioning

confidence: 99%

Laser and Electron Beam Additive Manufacturing Methods of Fabricating Titanium Bone Implants

et al. 2017

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Featured Application: This work is a detailed comparison of the direct laser and electron additive manufacturing methods, which could help scientific research institutes and companies choose the best 3D printer system for the fabrication of titanium implants.Abstract: Additive Manufacturing (AM) methods are generally used to produce an early sample or near net-shape elements based on three-dimensional geometrical modules. To date, publications on AM of metal implants have mainly focused on knee and hip replacements or bone scaffolds for tissue engineering. The direct fabrication of metallic implants can be achieved by methods, such as Selective Laser Melting (SLM) or Electron Beam Melting (EBM). This work compares the SLM and EBM methods used in the fabrication of titanium bone implants by analyzing the microstructure, mechanical properties and cytotoxicity. The SLM process was conducted in an environmental chamber using 0.4-0.6 vol % of oxygen to enhance the mechanical properties of a Ti-6Al-4V alloy. SLM processed material had high anisotropy of mechanical properties and superior UTS (1246-1421 MPa) when compared to the EBM (972-976 MPa) and the wrought material (933-942 MPa). The microstructure and phase composition depended on the used fabrication method. The AM methods caused the formation of long epitaxial grains of the prior β phase. The equilibrium phases (α + β) and non-equilibrium α' martensite was obtained after EBM and SLM, respectively. Although it was found that the heat transfer that occurs during the layer by layer generation of the component caused aluminum content deviations, neither methods generated any cytotoxic effects. Furthermore, in contrast to SLM, the EBM fabricated material met the ASTMF136 standard for surgical implant applications.

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In situ tailoring microstructure in additively manufactured Ti-6Al-4V for superior mechanical performance

Cited by 537 publications

References 29 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

New Development in Selective Laser Melting of Ti–6Al–4V: A Wider Processing Window for the Achievement of Fully Lamellar α + β Microstructures

Laser and Electron Beam Additive Manufacturing Methods of Fabricating Titanium Bone Implants

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