Main Physical Phenomena in Metal Powder Bed Fusion

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1 Main Physical Phenomena in Metal Powder Bed Fusion Q. 3 & 8 DC Workshop Oct 7-9, 2015 This work was performed under the auspices of the U.S. Department of Energy by under contract DE-AC52-07NA Lawrence Livermore National Security, LLC LLNL- PRES

2 an us c Figure 8 Hydrogen pore density of SLM samples depending on the scan speed; ds,2 = 1 PL = 910 W M 3.3 Influence of the beam on the hydrogen pore density For SLM samples built up with the two different beam s ds,1 = 0.3 m Defects are born at the single powder layer may seed more defects in subsequent layers ed ds,2 = 1 mm the latter show an approx. 10-fold higher pore density (Figure 9). X. Zhou et al. / Acta Materialia 98 (2015) 1 16 Rough surface, bad wetting Low density part, bad quality W. King, J. Mat. Proc. Tech Ac ce pt X. Zhou et al. / Acta Materialia 98 (2015) 1 16 Pores in Keyhole-mode Incomplete melting X. Zhou, Act. Mat C. Weingarten J. Mat. Proc. Tech Figure 9 Hydrogen pores in AlSi10Mg SLM samples built up with dried powder (at = 90 C) a beam of ds,1 = 0.3 mm (vs = 2250 mm/s P = 0.4%) ds,2 = 1 mm (vs = 250 mm/s P = 9.2%) (right) Selective melting process is complex: It is easy to introduce defects. Our understing of the interplay between process parameters ( /speed, powder is calculated still lacking. temperature distribution of thedistribution/thickness ) melting process in SLM was with an simulation. results are shown in Figure 10. When the beam ds,1 is u 2 higher local temperature Tmax, C is reached. This is caused by the

3 Laser Laser scan speed Substrate dimensions Physics Pore Generation Recommendations 200W 1500mm/s 1000x300x50µm3 What is the driving physics? How do pores form evolve? Guidance for better parameter choice? 3

4 LLNL under project tracking code 13-SI-002. (a) (a) (b) (b) (c) (b) (c) (c) 60 µm FWHM 60 µm FWHM 60 µm FWHM 50 µm FWHM 50 µm FWHM 50 µm FWHM 50 µm FWHM 50 µm FWHM HM!"#"!"$%"&'.515Wcm/s 22.5 W15 cm/s cm/s W 45 W 4530 W cm/s45 W30 cm/s 30 cm/s 22.53W cm/s22.5 W3 cm/s 3 cm/s S#?"#TF!=/64!b@*.267*5!a6,7C25!B6/!R;D*7C0;!Q*7,B*C.,/278bZ!:::F7*CB*4F6/8! y (µm) y (µm) y (µm) y (µm) y (µm) y (µm) y (µm) y (µm) RFQF!X,-07C12K9!OF!HF!S7F;FTF!bI04<0/*.,/0!;0<07;07.!()?W74!5*+0/!*-+6/<.267!-E! /278!8/*;0!*5,427,49!.2.*72,4!*7;!+.005!*556E!+,/B*C0+bF! RFcF!d,+*/6D9!GF!OF!S#?"?TF!bQ6;05278!.10!27.0/*C.267!6B!5*+0/!/*;2*.267!:2.1!<6:;0/! -0;!*.!+050C.2D0!5*+0/! bF!%&'()*(+%,-*./)0!1+"9!$)"W$>%F! RFcF!d,+*/6D9!GF!eF!S#??>TF!bQ6;05!6B!X*;2*.267!*7;!M0*.!I/*7+B0/!27!P*+0/WV6:;0/! LLNL experiment (uncertainty +/-5µm) G7.0/*C.267!f670!*.!O050C.2D0!P*+0/!Q05.278bF!2-3, ,04(6.,!1+:;:9!?(#"?"F! 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F!%,-/3*8)-4+?4@)4..,)4@1+A.(.0,*&+04/+B.C.5-DE.48!1+$9!$&W%&F! a*/6527!h6/70/9!rf!^f!s#?"$tf!b=,7;*407.*5!c67+652;*.267!40c1*72+4+!;,/278! +050C.2D0!-0*4! !6B!<6:;0/+bF!=-/.5)4@+04/+F)E3508)-4+)4+=08.,)05(+04/+ F*).4*.+04/+?4@)4..,)4@!1+G:9!?)&?""F! a*/6527!h6/70/9!if!rf!s#?""tf!bq0+6+c6<2c!+24,5*.267!6b!+050c.2d0!-0*4! ! cm/s 50%15 cm/s 15 cm/s 50% 50% 3 cm/s 50%3 cm/s 3 cm/s100% 100% 30 cm/s 100%30 cm/s 30 cm/s 91 w 380 mm/s </6C0++0+bF!2-3, =08.,)05(+%,-*.(()4@+9.*&4-5-@'!1+G::9!>()W>)(F! a1*7;/*+0k1*/9!of!s">'"tf!h7'/,-/'40e)*(+04/+7'/,-e0@4.8)*+f80i)5)8'hj!nab6/;z! s-sections 6 Fig. Cross-sections 6 Cross-sections of tracks of of ontracks the stainless tracks on the on stainless steel the stainless substrate steel substrate steel with-substrate with- witha5*/07;67f! j*+9!of!s#??$tf!bv1e+2c*5!*+<0c.+!6b!</6c0++!c67./65!27!+050c.2d0!5*+0/!+27.0/278!6b! powder: calculated out powder: calculated phase calculated diagrams phase phase diagrams upper diagrams row upper upper row experimental row experimental miexperimental mi- mi40.*5+bf!k/c04*./+?4@)4..,)4@+=08.,)05(!1+"9!(?"w(""f! ower raphs crographs row lower lower row row =/20;4*79!dF!S#?""9!@6DF!"'TF!bV*.2C50V*CK!k+0/+l!Q*7,*5bF!LLMLNF=N$">#;:!F! P2D046/09!aR9!kORZ!P*:/07C0!P2D0/46/0!@*.267*5!P*-6/*.6/EF! d,9!jf!qf!s#?"#tf!bp*+0/!*;;2.2d0!4*7,b*c.,/278!6b!40.*552c!c64<6707.+z!4*.0/2*5+9! served served agreement between agreement between the experiment between the experiment the experiment the model theshown model theinmodel shown shown in in proximately R, ch </6C0++0+!*7;!40C1*72+4+bF!<48.,408)5+=08.,)05(+A.C).O!1+"!9!"$$W"'%F! which is approximately is equal approximately to equal the to equal the toagreement the served d,/.50/9!=fwgf!hfwmf!s#?"$tf!bo24,5*.267!6b!5*+0/!-0*4! !6b!+.005!<6:;0/+!,+278! Fig. 6 Fig. indicates that6 the indicates that absorptivity thethat absorptivity thedoes absorptivity notdoes significantly not doessignificantly notin-significantly inin half!fwhm".!fwhm".!fwhm". Fig. 6 indicates.10!.1/00w; *5!d65,40!6b!b5,2;!40.16;bf!%&'()*(+%,-*./)0!1+$:9!)(%w)(>f! h/,.19!gfwvf!pf!s#??(tf!hp-4(-5)/08)-4+d&.4-e.40+)4+50(.,+04/+d-o/.,ni./+i0(./+ crease with crease temperature crease with temperature with temperature the contribution the contribution theof contribution the Marangoni of the of Marangoni the Marangon 50'.,./+E04360*83,)4@H!Sc65F!&'TF!aGXV!R77*5+!W!Q*7,B*C.,/278!.0C176568EF! We match theconvection bare plate melt pool well, although convection to heat convection transfer to dimensions heatto istransfer heat low. transfer is low. is low. we consider P0D2C19!cF!^F!S">'#TF!H%&'()*-*&.E)*05+7'/,-/'40E)*(HJ!V/07.2C0!M*55F! QF!X64-6,.+!*7;!PF!=/6E079!RF!dF!S#??&TF!bV16.6<E/6050C./2C!40*+,/0407.!6B! an average value for absorptivity. of thethe ofmaterial the beam of the is beam evaluated is beam evaluated byisitsevaluated traces by itsatby traces its traces at a ults eed obtained with are obtained SLM withmachine SLM with machine SLM machine.10/4*5!c67;,c.2d2.e!6b!40.*552c!<6:;0/+bf!2-3, kdd5)./+%&'()*(!1+q!9!?#%>?&f! reduced. reduced. full. full estimated full estimated from estimated such from ex-such fromexsuch ex QCa*55079!aF!S#?"#9!],5E!")TF!bRPi$jZ!R/-2./*/E!P*8/*780!i,50/2*7!I1/00W!*7;!I:6!!of m 50!W mofnominal 50 of nominal 50 reduced WA.,nominal ying Khairallah, S.A.,W Anderson, Mesoscopic Simulation Model of Selective Laser Melting of Stainless Steel Powder, j *5!q6;05278!*7;!o24,5*2.67!a*<*-252.ebf!llmlnkrfn"s"g:g!f!p2d0/46/09! ofis Materials Technology. periments periments isjournal around periments 100 around !isProcessing m.around However,!m. However, a!slow m. However, dependence a slow adependence slow on the dependence on the on the eter. nal m ar9!korz!p*:/07c0!p2d046/0!@*.267*5!p*-6/*.6/ef!. beam Taking. into Taking account Taking into account into account ssion is possible. is possible. refore, is possible. refore, two values refore, twoofvalues FWHM two values of FWHM of FWHM diamete m, l system, thelawrence the is is is 4 Livermore National Laboratory 60! m!were m 60!tested m60were!inmtested the were calculations. in tested the calculations. in the calculations. differ differ differ of 50!m of 50! ofm50

5 Khairallah, S.A., Anderson, A., Mesoscopic Simulation Model of Selective Laser Melting of Stainless Steel Powder, Journal of Materials Processing Technology. Simulation experiment showing Plateau-Rayleigh instability Melt pool profile H 26um Height 26µm Width 70µm D 20um Depth 20µm W 72um Experiment (uncertainty +/-5µm) H #$%&'()'*+,-&,$./,0+&"#1'"23-,4"+"-0'"3'31562'"2'-1&'3"7$+,-"52'8,.9:',2;'-1&'&<=&%"7&2-'8;:)'>1&'+,3&%' 56&%'"3'$""?',2;'-1&'39,2'3=&&;'"3'$7@3)'>1&'=56;&%'"2'8,:',2;'84:'"3'3"--"2#'52','3$43-%,-&'-1,-'"3' """A7'+52#B'#""A7'6";&',2;'!""A7';&&=)'8,:'"3','-5='C"&6)'89:'"3','3";&'C"&63)'8;:'"3','+52#"-$;"2,+'3+"9&' '-1&'7";;+&'5D'-1&'-%,9E)'>1&'"23-,4"+"-0'1,3','6,C&+&2#-1'"2'-1&'%,2#&'FGG.HGGA7)'8;:'"3'-1&' =&%"7&2-,+'-5='C"&6)'>1&'%&;'+"2&'"2'8;:'3&%C&3',3'39,+&',2;'"-'"3'FIHA7)'*J>'K'LMKNO'PQ'NKL>' SJ/OT simulation can predict well the main characteristics of the powder track eces. This phenomenon is described in the SLM literature (Kruth, 2007) is closely lated to Plateau-Rayleigh instability of a long cylindrical fluid jet breaking up into Lawrence Livermore National Laboratory roplets (Levich, 1962). physics governing this behavior is due to surface tension W D 5

6 Melt pool profile If Absorptivity is 0.4, then Depth is 60um Width is 80um If Absorptivity is 0.3, then Depth is 50um Width is 74um Depth width calculations improved due to added physics 6

7 I would like to apologize for taking out some slides. reason is these were submitted for publication in a journal. 7