2012 11-15-high-value-manufacturing-sirris-verlee

le centre collectif de l’industrie technologique belge

le centre collectif de l’industrie technologique belge

High Value Manufacturing

Density/porosity control of sintered 316L stainless steel parts shaped by additive manufacturing

15-11-2012

Table of contents

• Porous metallic parts • 3D-printing Prometal process • Sintering cycle • Characterization • Property ranges of 316L powders • Examples

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Porous metallic parts

• Shaping by powder metallurgy lots of parameters • Porosity range from a few % to 90%

• Application list: • Filtration • Distributing/dispersing/damping • Airing/cooling • Lightening • Catalysts supports • Prosthesis

• But simple geometries (Pressing, MIM)

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Porous metallic parts

• Additive manufacturing no limit in shape + integrated functionalities

• SLM 1 step no control of porosity • 3D-printing indirect route: shaping + sintering possibility to control porous characteristics

R10:

1000x500x280mm RXD: 60x40x15mm

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3D- Printing Prometal Process

1. Curing (green part)

2. Debinding - presintering (brown part)

3. Sintering Complete Partial (3’. Infiltration)

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Sintering cycle

• From a powder tap to full dense material • Passing by porous state

• Opened to 92% density, then closed

• Evolution functions of: • Initial state

• Packing density • Particle size distribution • Particle shape

• Sintering conditions • Temperature • Time • (Atmosphere)

• Stop at different stage to keep or eliminate porosity following

target application

Characterization

• Density – porosity (opened and closed) Archimedes (3 weightings) • Permeability k Darcy (flux Q through thickness L and surface A under DP)

• Pore size (bubble point and Hg porosimetry) Washburn


PALQk∆

=.

.. µ

Pd θγ cos..4−=

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Property ranges for 316L powders

0

5

10

15

20

25

30

35

40

60

65

70

75

80

85

90

95

100

1180 1200 1220 1240 1260 1280 1300 1320 1340 1360 1380 1400 1420 1440

Ope

ned

poro

sity

(%)

Rel

ativ

e de

nsity

(%)

Temperature (°C)

22µm 31µm 20-53µm 45-90µm

0,81 0,82 0,83 0,84 0,85 0,86 0,87 0,88 0,89

0,9

0 50 100 150 200 250 300 350

Den

sity

(-)

Time at sintering temperature (min.)

1315°C 1335°C 1345°C

• Effect of sintering T° (90min at T°) for 4 spherical powders

• Effect of sintering time at 3 T° for 31µm powder

Porous part Dense part

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• Pore size and permeability functions of opened porosity for 4 spherical powders

• Link between parameters:

• Powder size sets pore size • Thermal cycle sets final

density/porosity • all defines permeability

• Main challenge: shrinkage

control!

1,00E-16

1,00E-15

1,00E-14

1,00E-13

1,00E-12

0

5

10

15

20

25

30

35

0 5 10 15 20 25 30 35 40

Per

mea

bilit

y (m

²)

Mea

n po

re s

ize

(µm

)

Opened porosity (%)

22µm

31µm

20-53µm

45-90µm

Pore mean size Permeability



Gas atomised particles Water atomised particles

Sintered 90min at 1395°C

45-90µm powder

65% density – 35% opened porosity Mean pore size 35µm Permeability 10-12m²

47% density – 53% opened porosity Mean pore size 30µm Permeability 10-12m²

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Examples

Ø 50mm Pores 30µm

Perméa. 10-12 m² L 30mm

Ø 300mm Pores 35µm

Perméa. 10-12 m²

Ø 70mm Pores 30µm

Perméa. 10-12 m²

L 90mm Pores 35µm

Perméa. 10-12 m²

L 270mm Pores 17µm

Perméa. 5.10-13 m²

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Thank you for your attention !

[email protected]

2012 11-15-high-value-manufacturing-sirris-verlee

Technology