#3DPrintConfSJ

1. Materials for 3D Printing
D.L. Bourell
Temple Foundation Professor
The University of Texas at Austin
Inside 3D Printing – San Jose
September 17, 2013

2. Material Demands for 3D Printing
• Form Proper Feedstock
• Fabricator Processability
• Post-Processability as Needed
• Acceptable Service Properties

3. Categories of 3DP Processes (ASTM F2792)
binder jetting, n—an additive manufacturing process in which a liquid bonding
agent is selectively deposited to join powder materials.
directed energy deposition, n—an additive manufacturing process in which
focused thermal energy is used to fuse materials by melting as they are
being deposited.
material extrusion, n—an additive manufacturing process in which material is
selectively dispensed through a nozzle or orifice.
material jetting, n—an additive manufacturing process in which droplets of build
material are selectively deposited.
powder bed fusion, n—an additive manufacturing process in which thermal
energy selectively fuses regions of a powder bed.
sheet lamination, n—an additive manufacturing process in which sheets of
material are bonded to form an object.
vat photopolymerization, n—an additive manufacturing process in which liquid
photopolymer in a vat is selectively cured by light-activated polymerization.

4. Materials in General, over 3000 “Common” Types
Plastics (Polymers)
Weak
Deformable
Low Melting
Strong
Tough
High Melting
Wear Resistant
Brittle
Very High Melting
Source: Edupack Software, Granta Designs, 2012
Metals Ceramics

5. Polymers in General
Thermoplastics
Melt
Reversibly
Cross Link
Irreversibly
Large Elastic
Deformation
Various Web Sources
Thermosets Elastomers

6. Thermoplastics
Amorphous
• Melts over a range of
temperature
• “Pasty”
• Good for Material
Extrusion (FDM)
• ABS, PLA, PES
Various Web Sources
• Melts at a single
temperature
• “Liquidy”
• Good for LS
• PA (nylon), PEEK
Crystalline

7. Materials for 3D Printing
“Roadmap for Additive Manufacturing: Identifying the Future of Freeform Processing”, D.L. Bourell, M.C. Leu, D.W.
Rosen, eds, The University of Texas at Austin, 2009, 92 pages.
SL
LS, FDM SLM, EBM,
DED

8. Material for Additive Manufacturing
• Composites
• Binders
 Transient
 Permanent
• Support Structures
• Graded Structures
• Multi-Materials
“Roadmap for Additive Manufacturing: Identifying the Future of Freeform Processing”, D.L. Bourell, M.C. Leu, D.W.
Rosen, eds, The University of Texas at Austin, 2009, 92 pages.

9. Materials Grand Challenge in AM
• Quality
• Process Consistency, Repeatability
• Reliability
• Wide Diversity of Compositions
• Superior Structure and Properties
• Low (Feedstock and Processing) Cost

10. Materials Grand Challenge in AM
• Quality
• Process Consistency, Repeatability
• Reliability
• Wide Diversity of Compositions
• Superior Structure and Properties
• Low (Feedstock and Processing) Cost

11. Materials for Fused Deposition Modeling
(Amorphous Thermoplastics)
• ABS [Acryonitrile Butadiene Styrene] $7-115/lb
• Polycarbonate $113/lb
• PC/ABS Blend
• PLA [Polylactic Acid] $7-25/lb
• Polyetherimide (PEI) [Stratasys ULTEM] $220/lb
• Nylon Co-Polymer (new in 2012)
Source: 2012 Wohlers Report

12. Materials for
Stereolithography and Material Jetting
(Proprietary Thermosets, ~$100/lb)
• Acrylics
• Acrylates
• Epoxies
• “ABS-like” (Material Jetting)
Source: 2012 Wohlers Report

13. Materials for Laser Sintering
(Crystalline/Semi-Crystalline Thermoplastics)
• Polyamide (Nylon) 11 and 12 ~$40/lb
Neat
Glass Filled
Carbon Filled
Metal (Al) Filled
• Polystyrene (Lost Wax Patterns)
• Polypropylene
• Polyester (“Flex”)
• Polyetheretherkeytone (PEEK)
• Thermoplastic Polyurethane (new in 2012)
• Nylon 6 (new in 2012)
Source: 2012 Wohlers Report

14. Metals for AM (BJ, DED, PBF, SL)
• Tool Steel ~$50/lb
• Stainless Steel ~$50/lb
• Aluminum Alloys ~$50/lb
• Co-Cr Alloys ~$55-250/lb
• Nickel Alloys ~$95-125/lb
• CP Titanium ~$150-400/lb
• Ti-6Al-4V ~$150-400/lb
• Gold
• Silver
Source: 2012 Wohlers Report
Most Popular:
SLM
EBM
BJ (ExOne)
DED (LENS, POM, etc.)
LOM (UAM)

15. • Common 3DP materials are generally not patent
protected
• Material cost is high for consumers, but new
suppliers do not seem to be entering the
marketplace
• Perhaps the price will come down as material
usage volume increases due to adoption
• My impression is that there is little consumer
loyalty to a specific brand of material
Materials Perspectives

16. • Materials will be demanded in a quantity to justify
volume production with concomitant reduction in
unit cost for the user. Material cost will drop.
• Lower cost will increase usage, engendering
greater demand,…
• Several “mini-suppliers” or niche product
companies have appeared in the last 5-10 years
and seem to be surviving.
Materials Forecast

17. Stress or Strength [Take a load without failing]
Ductility [Permanent elongation at failure]
Stiffness [Measure of springiness]
Fracture Toughness [Ultra-strong or ultra-brittle]
Fatigue [Elastic cyclic loading]
Mechanical Properties

18. Strength
Strength is an intrinsic term.
F

19. Bending is Not Tension!
F
L

20. Strength

21. Strength
• Yield Strength – Stress to start permanent
deformation
• Ultimate Strength – Stress needed to break
the sample into two pieces

22. Strength
Metric Unit of stress is the “megapascal” MPa

23. <0.5 ksi A part “falls apart”
20 ksi Most Woods/Plastics
80 ksi Structural Steel/Aluminum
400 ksi High-Strength Steel
Strength

24. Strength
2012 Edupack Material Selector Software
3000 Commercial Materials

25. Summary of AM Mechanical Behavior
Metals Polymers Non-Metallics
Modulus of
Elasticity
Porosity Driven
(Power Law)
Porosity Driven
(Power Law)
Porosity Driven
Strength/Ductility Porosity Driven
Isotropic (High )
Porosity Driven
Anisotropic (Ductility)
Porosity Driven
Weibull Works
Fatigue e<0.5UTS or no e -
Fracture
Toughness
Less or equal to bulk -
1
th

26. Processing Effects on Porosity in SLM
Processed 17-4 Stainless Steel
A.B. Spierings, K. Wegener, G. Levy, “Designing Material Properties Locally with Additive Manufacturing
Technology SLM”, Proc. SFF Symposium (2012), pp. 447-455.
Power = 190 W
Vscan = 1.30 m/s
Tlayer = 50 m
Power = 190 W
Vscan = 0.80 m/s
Tlayer = 30 m

27. Examples of Porosity in EBM Ti-6Al-4V
Khalid Rafi, H., Karthik N.V., Thomas L. Starr, Brent E. Stucker, “Defect formation in EBM parts built in horizontal
orientation”, Proc. SFF Symposium (2012), pp. 456-467.

28. Khalid Rafi, H., Karthik N.V., Thomas L. Starr, Brent E. Stucker, “Defect formation in EBM parts built in horizontal
orientation”, Proc. SFF Symposium (2012), pp. 456-467.
Examples of Porosity in EBM Ti-6Al-4V

29. Strength
J.P. Kruth, et al., “Binding Mechanisms in Selective Laser Sintering and Selective Laser Melting”, SFF Symposium
Proceedings, Univ. Texas at Austin, 2004, pp. 44-58.
316L Stainless Steel
SLM, As Processed
27.5 ksi
70-100 ksi

30. SLM 316 Metals
316L Stainless Steel (Stress Relieved)
SLM Conventional
Yield Strength, ksi 92.8 45.0
Ult. Strength, ksi 110 89.9
Elongation, % 30 30
15-5 PH Stainless Steel (H900)
SLM Conventional
Yield Strength, ksi 160 170
Ult. Strength, ksi 213 190
Elongation, % 15 10
unpublished results, Tom Starr, U. Louisville

31. SLM of Ti-6Al-4V
Table for AM Ti-6Al-4V (unpublished results, Tom Starr, U. Louisville)

32. Modulus of Elasticity
C.E. Majewski and N. Hopkinson, “Effect of section thickness and build orientation on tensile properties and
material characteristics of Laser Sintered nylon-12 parts”, SFF Symposium Proceedings, Univ. Texas at Austin, 2010,
pp. 422-34.
Nylon 12
200
400
600
0
Stiffness(ksi)

33. Modulus of Elasticity
S. Rüsenberg, L. Schmidt, and H.-J. Schmid, “Mechanical and Physical Properties – A Way to Assess Quality of Laser
Sintered Parts”, SFF Symposium Proceedings, Univ. Texas at Austin, 2011, pp. 239-51.
Virgin PA2200 (Nylon 12) DIN EN ISO 527-1 Test Method
200
400
0
Stiffness(ksi)

34. Strength and Ductility
R.S. Keicher, A.M. Christiansen and K.W. Wurth, “Electron Beam Melted (EBM) Co-Cr-Mo Alloy for Orthopaedic
Implant Applications”, SFF Symposium Proceedings, Univ. Texas at Austin, 2009, pp. 428-36.
66Co-28Cr-6Mo
EBM, HIP, Homogenized
(ksi) (ksi)

35. D.K. Leigh, Harvest Technologies, priv. comm., 2011.
LS Bulk*
Yield (MPa) 3280 8400
Tensile (MPa) 7250 8850
% Elongation 27 350
*CES Edupack Matl Selector, Version 7.0.0, Granta Ltd., 2011
Mechanical Behavior
of LS Nylon

36. Strength
1.5
1.55
1.6
1.65
1.7
1.75
1.8
1.85
1.9
-0.14 -0.12 -0.1 -0.08 -0.06 -0.04 -0.02 0
Log(H)
Log( )
E. Yasa, et al., “Microstructure and Mechanical Properties of Maraging Steel 300 after Selective Laser
Melting”, SFF Symp., 2010, pp. 383-396
SLM Maraging Steel 18Ni300
Various Layer Thicknesses
R.M. German, “Powder Metallurgy
and Particulate Materials
Processing”, MPIF, Princeton
NJ, 2005, p. 385.

37. Strength
M.K. Agarwala, D.L. Bourell, B. Wu, J.J. Beaman, “An Evaluation of the Mechanical Behavior of Bronze-Ni
Composites Produced by Selective Laser Sintering”, SFF Symposium Proceedings, H.L. Marcus, J.J. Beaman, J.W.
Barlow, D.L. Bourell and R.H. Crawford, eds., Austin TX, 193-203 (1993).
Room-Temperature Tensile Strength of Pre-Mixed SLS (90Cu-10Sn) Bronze and
Commercially Pure Nickel Powder as a Function of Relative Density = 1- . (a) As SLS
Processed, (b) SLS Processed and Sintered at 900-1100 C for 1 to 10 hr.

38. Mechanical Properties of AM Parts
Ductility
Relative Ductility as a Function of Fractional
Porosity for Pure Iron. Various Particle Sizes and
Purity. [From Haynes, Powder
Met., 1977, 20, 17-20]
2/12
2/3
1
1
)0(
)0(
CDuctility
Ductility

39. Ductility
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0 0.1 0.2 0.3 0.4 0.5
Elongation
Relative Porosity
LS Polyamide 12
C = 4000
D.K. Leigh, D.L. Bourell, J.J. Beaman, “Basis for Decreased Mechanical Properties of Polyamide in Selective Laser
Sintering” Proc. SFF Symposium, Austin TX, 2011.
R. Haynes, “A Study of the Effect of
Porosity Content on the Ductility of
Sintered Metals”, Powder Metallurgy 20
(1977) pp. 17-20.

40. SLM Ti-6Al-4V Based on Post-Process
Anneals (Furnace Cooled)
Thöne, M., S. Leuders, A. Riemer, T. Tröster, H.A. Richard, “Influence of heat-treatment on Selective Laser Melting
products – e.g. Ti6Al4V”, Solid Freeform Fabrication Proceedings, (2012), pp. 492-498.

41. Ti Ductility
Ti-6Al-4V
SLM, As
Processed
Compared to
Annealed and
Solution Treated
and Aged Ti64.
B. Vandenbroucke and J.P. Kruth, “Selective Laser Melting of Biocompatible Metals for Rapid Manufacturing of
Medical Parts”, SFF Symposium Proceedings, Univ. Texas at Austin, 2006, pp. 148-159.

42. Aging Effects on Mechanical Properties of SL Polymer
Karina Puebla, Karina Arcaute, Rolando Quintana, Ryan B. Wicker, “Effects of environmental
conditions, aging, and build orientations on the mechanical properties of ASTM type I specimens manufactured
via stereolithography”, Rapid Prototyping Journal, 18#5 (2012), pp. 374–388.

43. ASTM Standards wrt
Materials/Properties
Issued Standards
F2924-12 Standard Specification for Additive Manufacturing Titanium-6 Aluminum-4
Vanadium with Powder Bed Fusion
Standards Under Development
WK27752 New Specification for Powder Bed Fusion of Plastic Materials
WK33776 New Specification for Additive Manufacturing Nickel Alloy (UNS N07718) with
Powder Bed Fusion
WK33833 New Specification for Additive Manufacturing Cobalt-28 Chromium-6
Molybdenum with Powder Bed Fusion
WK37654 New Practice for Machine Operation for Directed Energy Deposition of Metals
WK37658 New Specification for Additive Manufacturing Nickel Alloy (UNS N06625) with
Powder Bed Fusion
WK37683 New Specification for Additive Manufacturing Titanium-6 Aluminum-4 Vanadium
with Extra Low Interstitials with Powder Bed Fusion

44. Summary of AM Mechanical Behavior
• Mechanical behavior is predictable based on the
traditional understanding of microstructure and
processing.
• Porosity has a strong influence on the mechanical
behavior.
• Anisotropy is not an issue if parts are built with low
porosity and good layer interface.
• Polymers produced using best practice have isotropic
strength and anisotropic ductility.

45. Overall Summary
• 3DP is hereto stay, and the market is developing
explosively
• Materials for 3DP offers an opportunity for business
venture
• Market timing is a factor for entry into 3DP materials
• 3DP fabricators will continue to proliferate driven by
expiration of founding patents over the next 1-5 years
• There is not much brand loyalty of materials among
users of 3DP materials

47. Mechanical Properties of RM Parts
Fatigue/Fracture
•Strongly Influenced by Residual Porosity
•Morphology Important - Pore Volume Fraction, Size, Spacing, Especially on the
Surface
•Pores Generally Increase Threshold Stress Intensity for Crack Initiation
•Pores Generally Decrease the Resistance to Crack Propagation
•Fatigue Limits in Low-Porosity Materials are Generally 0.35(UTS) Compared to
0.5(UTS) for Fully Dense Materials

48. Fatigue
Reid, Fatigue of Fused Deposition Modeled (FDM) Acrylonitrile Butadiene Styrene (ABS) Stage Three individual
Project MEC 3098, Newcastle University School of Mechanical and Systems Engineering 2011.
Fatigue of FDM Processed ABS polymer

49. Fatigue
P.A. Kobryn and S.L. Semiatin, “Mechanical Properties of Laser-Deposited Ti-6Al-4V”, SFF Symposium
Proceedings, Univ. Texas at Austin, 2001, pp. 179-186.
LENS Processed Ti-6Al-4V, Stress Relieved or HIPped

50. Fracture Toughness
P.A. Kobryn and S.L. Semiatin, “Mechanical Properties of Laser-Deposited Ti-6Al-4V”, SFF Symposium
Proceedings, Univ. Texas at Austin, 2001, pp. 179-186.
LENS Processed Ti-6Al-4V, Stress Relieved or HIPped