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Metals 2017,7, 91
45◦orientedpartsbecauseparticlesadhereonthestrut side facingthepowderbed.OnEBMparts,
thesamephenomenonleads toa lowerroughnessof the45◦orientedparts. Theparticles thatadhere
onthesurfacedecrease theroughnessbecausesomeunevennessgetsfilled.
Foxetal. [44] foundin theirworkashiftbetweensurfacesdominatedbypartiallymeltedpowder
particlesandsurfacesdominatedbymaterial fromthere-solidifiedmelt track.Withadecreaseof the
surfaceangle, theRa value increased.Adecreasedsurfaceangle isequivalent to the45◦ in thiswork.
The0◦ orientation in thisworkmeansahigher surfaceangle. These results are consistentwith the
previous resultsofTriantaphyllouetal. [45]whofounddifferencesbetweenupskinanddownskin
surfacesaswellas theorientationangles. Thedifferences inaverageroughnessRa foundbetweenthe
EBMandtheSLMmethodarealsoconfirmedhere.
There isasignificantdifferencebetweentheSLMparts (HIPandNoHIP) in the0◦orientation
(p<0.001). Inproductionthisdifference,however, is likelytobewithintheaccuracyfluctuationsrange.
TheroughnessRa ofSLM-manufactured(HIPandNoHIP)partsweresignificantly (p<0.001) lower
for the0◦orientation thanfor theEBMparts. In the45◦orientation, theroughnesswasonlydifferent
betweenSLMHIPandEBM(SLMHIP<EBM;p<0.05). These relationships are also seen for the
roughnessRz.
ThevaluesobtainedforSLM-andEBM-manufacturedTi6Al4Vpartscorrespondtothosefromthe
literature.Accordingly, theSLM-partsshowafar lowerdeviationfromatheoretical smoothsurface
thatcanbeconsideredanindicator forastableandaccuratemanufacturingprocess. Besidespowder
sizedistribution, the layer thickness in thepowder feedandthepowderbedsystem, the laserbeam
diameter itself hasan influenceonsurface roughness [13]. Higher roughnessvaluesofEBMparts
are typicallydue to theprocessparameters. Asmoother surface and therefore lower roughness is
thereforepossible throughtheoptimizationofprocessparameters.
3.3.VickersHardness
Thehardnessofpartsmanufacturedinthe45◦orientationweresignificantly(SLM-NoHIPp<0.05;
EBM-NoHIPp<0.001) lower than in thosemanufactured in the0◦orientation. Thiscorrelation isnot
seen in theheat-treatedSLM-manufacturedparts.Heat treatmentof theSLM-manufacturedparts led
toasignificantly lowerhardness (inbothorientationsp<0.001).WhenSLM-andEBM-manufactured
partswithnoheat treatmentwerecompared, theSLMpartshadinbothorientationsasignificantly
(p<0.001) lowerhardness thantheEBMparts. Theresults forhardnessareshowninFigure13.
Figure13.BoxplotsofthemeasuredhardnessHV10. Boxplotsgivethemedianvalue, theinterquartile
range(IQR: intervalbetweenthe25thand75thpercentile,bluerectangle)andtheextremumvalues
(n=40); statistical significance levels (*p<0.05; ***p<0.001).Nosignificantdifferences fromsimilar
otherpossiblemanufacturingsystemswererevealed.
63
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Buch 3D Printing of Metals"
3D Printing of Metals
- Titel
- 3D Printing of Metals
- Autor
- Manoj Gupta
- Herausgeber
- MDPI
- Ort
- Basel
- Datum
- 2017
- Sprache
- englisch
- Lizenz
- CC BY-NC-ND 4.0
- ISBN
- 978-3-03842-592-2
- Abmessungen
- 17.0 x 24.4 cm
- Seiten
- 170
- Schlagwörter
- 3D printing, additive manufacturing, electron beam melting, selective laser melting, laser metal deposition, aluminum, titanium, magnesium, composites
- Kategorien
- Naturwissenschaften Chemie