0
Research Papers

Pore Formation in Laser-Assisted Powder Deposition Process

[+] Author and Article Information
L. Wang

Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, MS 39762

P. Pratt

Department of Mechanical Engineering, Mississippi State University, Mississippi State, MS 39762

S. D. Felicelli, H. El Kadiri, J. T. Berry, P. T. Wang, M. F. Horstemeyer

Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, MS 39762; Department of Mechanical Engineering, Mississippi State University, Mississippi State, MS 39762

J. Manuf. Sci. Eng 131(5), 051008 (Sep 08, 2009) (9 pages) doi:10.1115/1.3184087 History: Received November 25, 2008; Revised May 18, 2009; Published September 08, 2009

Pore formation remains a concern in the area of rapid manufacturing by the laser engineered net shaping process. Results usually conflict on the origin of these pores; whether it should stem from an effect due to the physical/mechanical properties of the material or from an effect purely related to the processing parameters. We investigated this problem spanning a range of process parameters for deposition and using three different material powders, namely, an AISI 410 grade stainless steel, AISI 316L grade stainless steel, and AISI 4140 grade medium-carbon low alloy steel. The volume fraction, number density, and size distribution of pores were quantified using X-ray computed tomography and optical microscopy. Pores formed both at the interface between the adjacent layers and within the bulk of the layer. They were systematically sensitive to both the powder material composition and the process parameters.

FIGURES IN THIS ARTICLE
<>
Copyright © 2009 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 5

Optical photography of AISI 410 thin plate for sample S4 showing gas porosity: (a) transverse direction and (b) longitude direction

Grahic Jump Location
Figure 9

Porosity distribution in sample C6: (a) 2D XRCT snapshot of sample C6 and (b) visual representation of the presence of porosity using the results of X-ray computed tomography for sample C6

Grahic Jump Location
Figure 10

LENS deposited AISI 316L sample C7 from LENS 850 system shows both interlayer porosity and internal gas porosity

Grahic Jump Location
Figure 11

(a) SEM image of LENS deposited AISI 316L sample C7, (b) high magnification (700×) view of interlayer porosity, (c) SEM image shows the unmelted powder in the interlayer porosity, and (d) EDX analysis of the defect showing the presence of oxygen

Grahic Jump Location
Figure 12

2D XRCT snapshots of LENS samples (a) AISI 316L sample (C1), (b) AISI 4140 sample (C8), and (c) AISI 410 sample (C9)

Grahic Jump Location
Figure 13

(a) Overall fracture surface inspected with SEM for LENS deposited AISI 4140 sample (C8) and (b) a higher magnification view of the image (300×) showing the unmelted powder

Grahic Jump Location
Figure 14

Photo micrographs of as-polished LENS powders (a) AISI 316L, (b) AISI 4140, and (c) AISI 410

Grahic Jump Location
Figure 1

LENS-produced single-walled AISI 410 plate

Grahic Jump Location
Figure 2

Optical photography of AISI 410 thin plate for sample S1 showing gas porosity in the transverse direction: (a) gas pores about 50 μm in diameter and (b) gas pores about 100 μm in diameter

Grahic Jump Location
Figure 3

Optical photography of AISI 410 thin plate for sample S2 showing gas porosity: (a) transverse direction and (b) longitude direction

Grahic Jump Location
Figure 4

Optical photography of AISI 410 thin plate for sample S3 showing gas porosity: (a) transverse direction and (b) longitude direction

Grahic Jump Location
Figure 6

Visual representation of the presence of porosity using the results of X-ray computed tomography for LENS deposited AISI 316L cylinder samples: (a) geometry of sample (L=3–8 mm, D=3–5 mm, depends on specimens), (b) C1, (c) C2, (d) C3, and (e) C4

Grahic Jump Location
Figure 7

Visual representation of the presence of porosity using the results of X-ray computed tomography for different locations of sample C5: (a) bottom, (b) center, and (c) top

Grahic Jump Location
Figure 8

Distribution of calculated sphericity coefficient plotted as a function of the calculated equivalent diameter for each pore in each LENS specimen

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In