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Materials 2016, 9(12), 975; doi:10.3390/ma9120975

Performance of High Layer Thickness in Selective Laser Melting of Ti6Al4V

1
School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
2
Beijing Institute of Astronautical Systems Engineering, Beijing 100076, China
*
Author to whom correspondence should be addressed.
Academic Editor: Guillermo Requena
Received: 22 October 2016 / Revised: 13 November 2016 / Accepted: 22 November 2016 / Published: 1 December 2016
(This article belongs to the Special Issue Metals for Additive Manufacturing)
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Abstract

To increase building rate and save cost, the selective laser melting (SLM) of Ti6Al4V with a high layer thickness (200 μm) and low cost coarse powders (53 μm–106 μm) at a laser power of 400 W is investigated in this preliminary study. A relatively large laser beam with a diameter of 200 μm is utilized to produce a stable melt pool at high layer thickness, and the appropriate scanning track, which has a smooth surface with a shallow contact angle, can be obtained at the scanning speeds from 40 mm/s to 80 mm/s. By adjusting the hatch spacings, the density of multi-layer samples can be up to 99.99%, which is much higher than that achieved in previous studies about high layer thickness selective laser melting. Meanwhile, the building rate can be up to 7.2 mm3/s, which is about 2 times–9 times that of the commercial equipment. Besides, two kinds of defects are observed: the large un-melted defects and the small spherical micropores. The formation of the un-melted defects is mainly attributed to the inappropriate overlap rates and the unstable scanning tracks, which can be eliminated by adjusting the processing parameters. Nevertheless, the micropores cannot be completely eliminated. It is worth noting that the high layer thickness plays a key role on surface roughness rather than tensile properties during the SLM process. Although a sample with a relatively coarse surface is generated, the average values of yield strength, ultimate tensile strength, and elongation are 1050 MPa, 1140 MPa, and 7.03%, respectively, which are not obviously different than those with the thin layer thickness used in previous research; this is due to the similar metallurgical bonding and microstructure. View Full-Text
Keywords: selective laser melting; high layer thickness; coarse powders; Ti6Al4V; microstructure; mechanical properties; defects selective laser melting; high layer thickness; coarse powders; Ti6Al4V; microstructure; mechanical properties; defects
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MDPI and ACS Style

Shi, X.; Ma, S.; Liu, C.; Chen, C.; Wu, Q.; Chen, X.; Lu, J. Performance of High Layer Thickness in Selective Laser Melting of Ti6Al4V. Materials 2016, 9, 975.

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