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Effects of Melt Pool Variables and Process Parameters in Laser Direct Metal Deposition of Aerospace Alloys

Shah, Kamran and Pinkerton, Andrew J. and Salman, Ahmad and Li, Lin (2010) Effects of Melt Pool Variables and Process Parameters in Laser Direct Metal Deposition of Aerospace Alloys. Materials and manufacturing processes, 25 (12). pp. 1372-1380. ISSN 1042-6914

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Abstract

Despite considerable advances in of laser direct metal deposition (LDMD) process optimization, there is rather limited work reported on the effects of melt pool variables on the final deposit characteristics. This article considers the effects of process parameters and melt pool characteristics on the deposition of Inconel 718 powder on a Ti-6Al-4V thin wall. A 1.5kW diode laser and LDMD system is used to produce a series of deposits. Images of the process are captured using Cu-vapor laser illumination and a high speed camera with long range microscopy optics, and quantitative results are extracted via image analysis. Process parameters such as carrier gas flow rate, powder mass flow rate and laser operating mode (CW and pulsed) and in process variables such as quantified melt pool disturbance, and final part characteristics are correlated and discussed. Scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and energy dispersive X-ray spectroscopy (EDS) are used to analyze deposited clads in terms of elemental composition and flow characteristics in the deposition melt pool. Melt pool disturbance is found to be a vital parameter in determining the surface roughness of the final part. An inverse relation between the mean surface disturbance of the melt pool and the surface roughness of the part is observed, and carrier gas flow rate and powder mass flow rate both affect the overall melt pool size. The work has implications for the selection of process parameters for commercial laser deposition processes-the speed with which powder is delivered to the melt pool as well as the mass flow rate may need to be taken into account when calculating build rate and for a good surface finish requiring minimum post process finishing a stable melt pool may actually be the worst situation.

Item Type: Article
Journal or Publication Title: Materials and manufacturing processes
Uncontrolled Keywords: Cladding ; Deposition ; Laser ; Inconel ; Ti-6Al-4 V
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Departments: Faculty of Science and Technology > Engineering
ID Code: 59509
Deposited By: ep_importer_pure
Deposited On: 26 Oct 2012 15:21
Refereed?: Yes
Published?: Published
Last Modified: 24 Jan 2014 05:34
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/59509

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