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Metals 2017,7, 64
isattributed to thefine-grainmicrostructuresobtained in thecompletedparts resulting inahigher
dislocationdensityofaustenitecells [49]. Thismakesslipmotionalongthegrainboundariesdifficult,
thus increasing its strengthandresistance todeformation.Althoughthere is someporositycontent in
theSLMsamples inthisstudy, thedefect isnotexpectedtohaveasignificant impactonthemechanical
propertiesof thefinalpart since theSLMprocessingwasable toyieldhighdensification levels (>99%)
and the average porositywas also very low (~0.33%). Nevertheless, the porosity-microhardness
relationship isan importantaspect toconsiderwhenSLMisusedtomanufacture functionalpartssuch
asbone implantsandindustrial tools.
Figure11.Averagemicrohardness (HV)values forSLMandWMspecimens.
4.Conclusions
TheSLM-built316LSSsampleswereable toachievehighdensification levels (>99%)witha low
averageporositycontent (~0.82%). Eventhoughtheporositycontent in theSLM-builtpartswasvery
low, theporeswerenotevenlydistributedthroughout thesamples. Thehighestporositycontent in
theconcentratedregionswas foundtobe~1.68%whichwashigher thantheoverall average. Such
lowporositycontentdoesnotshowanobvious impactonthemechanicalpropertiesof theAM316L
SSsamplesproducedinthisstudy. Thehigheraveragemicrohardnessvaluesof theSLM-fabricated
316LSSpartscomparedto theirwroughtmanufacturedcounterpartwereprimarilyattributedto the
localisedmeltingof thepowder layers, and the rapidheating/coolingcycle involvedduringSLM
contributedto thefine-grainmicrostructures in thecompletedparts.
AuthorContributions:ShahirMohdYusufanalysedthedataandwrote themanuscript;YifeiChencarriedout
theexperimentsandanalysedthedata;RichardBoardmanpreparedandcarriedout theXCTscan;ShoufengYang
andNongGaoareexperts inadditivemanufacturing(AM)andmetallurgy, respectively,andtheyalsomanaged
andsupervisedtheproject.
Conflictsof Interest:Theauthorsdeclarenoconflictof interest.
References
1. Cherry, J.A.;Davies,H.M.;Mehmood,S.;Lavery,N.P.;Brown,S.G.R.; Sienz, J. Investigation into theeffectof
processparametersonmicrostructuralandphysicalpropertiesof316Lstainlesssteelpartsbyselective laser
melting. Int. J.Adv.Manuf. Technol. 2014,76, 869–879. [CrossRef]
2. Yusuf, S.M.; Gao, N. Influence of energy density on metallurgy and properties in metal additive
manufacturing.Mater. Sci. Technol. 2017. [CrossRef]
3. Guo,N.;Leu,M.C.Additivemanufacturing: Technology,applicationsandresearchneeds.Front.Mech. Eng.
2013,8, 215–243. [CrossRef]
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book 3D Printing of Metals"
3D Printing of Metals
- Title
- 3D Printing of Metals
- Author
- Manoj Gupta
- Editor
- MDPI
- Location
- Basel
- Date
- 2017
- Language
- English
- License
- CC BY-NC-ND 4.0
- ISBN
- 978-3-03842-592-2
- Size
- 17.0 x 24.4 cm
- Pages
- 170
- Keywords
- 3D printing, additive manufacturing, electron beam melting, selective laser melting, laser metal deposition, aluminum, titanium, magnesium, composites
- Categories
- Naturwissenschaften Chemie