Microstructure and Mechanical Properties of Direct Metal Laser Sintered Ti-6al-4v

Becker, Thorsten Hermann; Beck, Margit; Scheffer, Cornie

doi:10.7166/26-1-1022

Cited by 51 publications

(36 citation statements)

References 21 publications

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“…It has previously been reported that SLM-produced Ti-6Al-4V comprises martensitic microstructures with evidence of acicular α' phases and no β phase [13,18,20,16]. Given that this starting microstructure is vastly different from conventional forms, standard heat treatments will not necessarily provide the desired result.…”

Section: Heat Treatmentmentioning

confidence: 99%

“…In particular, the fast cooling rates and layer-wise building in the LaserCUSING process result in a fine, non-equilibrium phase and anisotropic behaviour [16][17][18][19][20]. This martensitic microstructure manifests in high hardness and high strength/low ductility material behaviour, requiring the use of heat treatments to obtain a balance of properties similar to those of the bulk materials.…”

Section: Introductionmentioning

confidence: 99%

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Heat Treatment of Ti-6al-4v Produced by Lasercusing

Becker¹,

Rooyen²,

Dimitrov³

2015

sajie

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LaserCUSING® is a selective laser melting (SLM) process that is capable of manufacturing parts by melting powder with heat input from a laser beam. LaserCUSING demonstrates potential for producing the intricate geometries specifically required for biomedical implants and aerospace applications. One main limitation to this form of rapid prototyping is the lack of published studies on the material performance of the resulting material. Studies of the material's performance are often complicated by dependence on several factors, including starting powder properties, laser parameters, and post-processing heat treatments. This study aims to investigate the mechanical properties of LaserCUSINGproduced Ti-6Al-4V and its performance relative to the conventional wrought counterpart. A combination of conventional and LaserCUSING-tailored heat treatments is performed. The resulting microstructures are studied and linked to the properties obtained from hardness tests. The findings highlight that LaserCused Ti-6Al-4V is competitive with traditional materials, provided that optimal parameters are chosen and parts are subject to tailored post-processing. In the as-built condition, LaserCused Ti-6Al-4V displays superior strength and hardness as a result of a martensitic microstructure, and a poorer performance in ductility. However, the material performance can be improved using tailored heat treatments. Careful consideration must be given to suitable post-processing before application in critical components in the aerospace or biomedical industry can occur. OPSOMMINGLaserCUSING® is 'n selektiewe lasersmeltproses met die vermoë om onderdele te vervaardig deur die smelt van poeier met hitte inset van 'n laserstraal. LaserCUSING toon die potensiaal om ingewikkelde geometrieë benodig vir biomediese implantate en lugvaart toepassings, te produseer. Een van die hoof beperkings tot hierdie vorm van blits prototipering is die tekort aan gepubliseerde studies oor die materiaaleienskappe van die gevolglike materiaal. Studies van die materiaaleienskappe is dikwels verder gekompliseer as gevolg van die invloed van verskeie faktore, soos die aanvanklike poeier eienskappe, die laser parameters en hittebehandelings na die lasersmeltproses. Hierdie studie beoog om die meganiese eienskappe van Ti-6Al-4V wat met LaserCUSING geproduseer is, en die vertoning daarvan relatief tot 'n konvensionele bewerkte eweknie, te ondersoek. 'n Kombinasie van konvensionele en aangepaste hittebehandelings is toegepas. Die resulterende mikrostrukture is ondersoek en verwantskappe tot die resultate van hardheidstoetse is gevind. Die resultate toon dat die Ti-6Al-4V met tradisionele materiale kan kompeteer mits optimale parameters vooraf gekies word en dat onderdele aangepaste hittebehandelings ondergaan. Die Ti-6Al-4V toon beter sterkte en hardheid, maar het swakker smeebaarheid. Noukeurige oorweging vir verwerking na die lasersmelt is nodig voor die toepassing daarvan op kritiese komponente. #This article is an extension of a paper presented at

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Section: Heat Treatmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Heat Treatment of Ti-6al-4v Produced by Lasercusing

Becker¹,

Rooyen²,

Dimitrov³

2015

sajie

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“…The process uses a scanning laser beam to form three dimensional objects in a layer-upon-layer build-up, based on three-dimensional computer aided design (CAD) model data input [3]. DMLS of Ti6Al4V is increasingly used in the biomechanical, aerospace, and automotive industries because of its ability to produce custom geometrically complex designs to high tolerances and with minimal material waste [4]. Ti6Al4V is used in the aforementioned industries because it is corrosion resistant, has a good strength-to-weight ratio and is bio-compatible [5,6].…”

Section: Sources Of Fatigue Failure In As-built Dmls Of Ti6al4v (Eli)mentioning

confidence: 99%

High Cycle Fatigue Properties of as-Built Ti6al4v (Eli) Produced by Direct Metal Laser Sintering

Malefane

Preez

Maringa

2017

SAJIE

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The high cycle fatigue (HCF) properties of direct metal laser sintering (DMLS) of Ti6Al4V (ELI) in three mutually orthogonal build directions were investigated by cycling specimens under load control, in a tension-tension fatigue testing machine. Semi-log graphs of maximum stress (S) against life (N) of the specimens produced along the respective three build directions were plotted, and the displayed endurance limits compared. Optical and scanning electron microscopy were used to compare and analyse the crack initiation and propagation characteristics of the specimens. The influence of the build direction on the fatigue properties of the tested specimens is discussed here. OPSOMMINGDie hoësiklus vermoeidheidseienskappe van direkte metaallaser sintering van Ti6Al4V in drie onderlinge ortogonale bourigtings is ondersoek deur monsters te onderwerp aan beheerde sikliese ladings met behulp van ŉ trek-trek vermoeidheidstoetsmasjien. Semi-log grafieke van maksimum spanning teen leeftyd (S-N grafieke) is vir die monsters saamgestel, saam met die onderskeie bou rigtings. Sodoende kon die vermoeidheidslewe vergelyk word. Optiese-en skandeer elektronmikroskopie is gebruik om die kraakvorming en -voortplanting te vergelyk en te analiseer. Die invloed van die bourigting op die vermoeidheidseienskappe van die monsters is bespreek. INTRODUCTIONWork done by the Centre for Rapid Prototyping and Manufacturing (CRPM) of the Central University of Technology Free State on the manufacture of parts using direct metal laser sintering (DMLS) of Ti6Al4V (ELI) powder has thus far been based on the static mechanical properties of such DMLS parts that have been stress-relieved. These static mechanical properties were found to conform to the properties of standard wrought Ti6Al4V (ELI) [1,2]. However, for DMLS Ti6Al4V (ELI) parts that are expected to experience cyclic loading, there is uncertainty that they will last their full operational life. This is due to limited available fatigue life data for the DMLS-produced alloy.This study presents baseline data and analyses on as-built DMLS Ti6Al4V (ELI), as a precursor to studies of DMLS Ti6Al4V (ELI) that is heat treated in order to tailor its microstructure to give the best high cycle fatigue (HCF) properties possible.

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“…A large degree of shrinkage occurs during liquid -solid transformation, thus accumulating considerable tensile residual stresses on the surface of the SLM produced components. The complex residual stresses (RS) that arise during cooling are regarded as key factors responsible for the distortion and even delamination of the final parts [9,10,[15][16][17]. These residual stresses may even cause process failure during the building phase [18].…”

Section: Introductionmentioning

confidence: 99%

“…However, although the mechanical properties have become close to those of bulk materials [3][4][5][6][7][8][9][10][11][12][13][14], SLM has some inherent drawbacks such as warping, cracking and detrimental tensile residual stresses (TRS). A large degree of shrinkage occurs during liquid -solid transformation, thus accumulating considerable tensile residual stresses on the surface of the SLM produced components.…”

Section: Introductionmentioning

confidence: 99%

Tailoring residual stress profile of Selective Laser Melted parts by Laser Shock Peening

Kalentics

Boillat

Peyre

et al. 2017

Additive Manufacturing

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Selective laser melting Laser shock peening 3D Laser shock peening Residual stress profile 15-5 PH stainless steel 316L stainless steel a b s t r a c t The paper describes a new approach in controlling and tailoring residual stress profile of parts made by Selective Laser Melting (SLM). SLM parts are well known for the high tensile stresses in the as -built state in the surface or subsurface region. These stresses have a detrimental effect on the mechanical properties and especially on the fatigue life. Laser Shock Peening (LSP) as a surface treatment method was applied on SLM parts and residual stress measurements with the hole -drilling method were performed. Two different grades of stainless steel were used: a martensitic 15-5 precipitation hardenable PH1 and an austenitic 316L. Different LSP parameters were used, varying laser energy, shot overlap, laser spot size and treatments with and without an ablative medium. For both materials the as-built (AB) residual stress state was changed to a more beneficial compressive state. The value and the depth of the compressive stress was analyzed and showed a clear dependence on the LSP processing parameters. Application of LSP on SLM parts showed promising results, and a novel method that would combine these two processes is proposed. The use of LSP during the building phase of SLM as a "3D LSP" method would possibly give the advantage of further increasing the depth and volume of compressive residual stresses, and selectively treating key areas of the part, thereby further increasing fatigue life.

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Microstructure and Mechanical Properties of Direct Metal Laser Sintered Ti-6al-4v

Cited by 51 publications

References 21 publications

Heat Treatment of Ti-6al-4v Produced by Lasercusing

Heat Treatment of Ti-6al-4v Produced by Lasercusing

High Cycle Fatigue Properties of as-Built Ti6al4v (Eli) Produced by Direct Metal Laser Sintering

Tailoring residual stress profile of Selective Laser Melted parts by Laser Shock Peening

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