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Research Papers

Densification of Porous Stainless-Steel SLS Components During Cold Isostatic Pressing

[+] Author and Article Information
Wei Qingsong, Du Yanying, Qu Bingbing

State Key Laboratory of Materials Processing and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China

Shi Yusheng1

State Key Laboratory of Materials Processing and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, Chinawqs_xn@163.com

1

Corresponding author.

J. Eng. Mater. Technol 132(1), 011015 (Dec 01, 2009) (7 pages) doi:10.1115/1.4000218 History: Received October 27, 2008; Revised July 26, 2009; Published December 01, 2009; Online December 01, 2009

The process that combines selective laser sintering (SLS) and cold isostatic pressing (CIP) can manufacture nearly fully dense metal components with complex geometries. However, the SLS component will shrink to a significant extent during the CIP process. The modified cam-clay model was used to describe the constitutive equation of porous stainless-steel SLS components. The densification process of SLS porous components was simulated using the finite element method. The visual distributions of shape change, displacement, density, and stress were obtained, which showed that SLS components shrank with the same shape as the original design over the CIP process. In addition, a relative uniform density distribution appeared in cold isostatic pressed components. The experiment measurements displayed that the shrinkage rate of SLS components during the CIP process in height direction was a little higher than that on the forming plane due to the layer-by-layer manufacturing process of SLS. On the forming plane, the dimensional errors between simulations and experiments for the cuboid and the gear components are lower than 1% and 3%, respectively. However, the errors in height direction of the two components increase to the range of 6% and 9%.

Copyright © 2010 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

The molecular structure of epoxy resin

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Figure 2

The sketch of bonding between epoxy resin and metal surface

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Figure 3

The flow chart of the SLS/CIP composite technique

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Figure 4

SEM of the fracture appearance of degreasing SLS components: (a) magnification of 200× and (b) magnification of 1000× for area I of (a)

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Figure 5

Geometry sketches and dimensional parameters of the studied components: (a) cuboid and (b) gear

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Figure 6

The symmetry schematic diagram and the simplified model of the gear component: (a) symmetry schematic diagram and (b) simplified model

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Figure 7

The mesh model for numerical simulations: (a) 1/8 of the cuboid component and (b) one single concave tooth of the gear component

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Figure 8

Deformations of SLS components after CIP by simulations: (a) cuboid and (b) gear

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Figure 9

Displacements of SLS components after CIP by simulations: (a) cuboid, (b) gear, (c) the symmetric section parallel to the axis direction, and (d) the symmetric section perpendicular to the axis direction

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Figure 10

Density distributions of SLS components after CIP by simulations: (a) cuboid and (b) gear

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Figure 11

Stress distributions of SLS components after CIP by simulation: (a) cuboid and (b) gear

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Figure 12

Relations between pressure and relative density of the cuboid components

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Figure 13

Micrograph appearances by means of the optical metallography method (magnification of 100×) for the SLS porous cuboid component after CIP processing with different pressures: (a) 200 MPa, (b) 300 MPa, (c) 400 MPa, (d) 500 MPa, (e) 600 MPa, and (f) 650 MPa

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Figure 14

SLS components before and after the CIP process: (a) cuboid and (b) gear

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Figure 15

The scanning of the laser beam during the SLS process: (a) scanning path of the laser beam, (b) sintering action of laser beam in area I, and (c) sintering action of the laser beam in area II

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