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Melt Pool characteristics on surface roughness and printability of 316L stainless steel in laser powder bed fusion (in EN)

Journal Article · · Rapid Prototyping Journal
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Purpose

Surface quality and porosity significantly influence the structural and functional properties of the final product. This study aims to establish and explain the underlying relationships among processing parameters, top surface roughness and porosity level in additively manufactured 316L stainless steel.

Design/methodology/approach

A systematic variation of printing process parameters was conducted to print cubic samples based on laser power, speed and their combinations of energy density. Melt pool morphologies and dimensions, surface roughness quantified by arithmetic mean height (Sa) and porosity levels were characterized via optical confocal microscopy.

Findings

The study reveals that the laser power required to achieve optimal top surface quality increases with the volumetric energy density (VED) levels. A smooth top surface (Sa < 15 µm) or a rough surface with humps at high VEDs (VED > 133.3 J/mm3) can serve as indicators for fully dense bulk samples, while rough top surfaces resulting from melt pool discontinuity correlate with high porosity levels. Under insufficient VED, melt pool discontinuity dominates the top surface. At high VEDs, surface quality improves with increased power as mitigation of melt pool discontinuity, followed by the deterioration with hump formation.

Originality/value

This study reveals and summarizes the formation mechanism of dominant features on top surface features and offers a potential method to predict the porosity by observing the top surface features with consideration of processing conditions.

Research Organization:
Savannah River National Laboratory (SRNL), Aiken, SC (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
89303321CEM000080
OSTI ID:
2582669
Journal Information:
Rapid Prototyping Journal, Journal Name: Rapid Prototyping Journal; ISSN 1355-2546
Publisher:
Emerald Group Publishing
Country of Publication:
United States
Language:
EN

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Related Subjects

Engineering
Materials Science