Graduate Studies
First Advisor
Michael Sealy
Date of this Version
12-9-2021
Document Type
Article
Citation
Avegnon K. L. M. and Sealy M. P. (2021) Mapping Defect Formation in Laser Powder Bed Fusion on a Hybrid Matsuura Lumex Avance-25. Master's Thesis. University of Nebraska Lincoln
Abstract
Additive manufacturing continues to have problems with porosity, surface quality, and residual stress. This two-part study focuses on (1) employing a non-detrimental technique to measure the resulting mechanical properties in additive manufacturing, namely residual stress and microhardness, and (2) improving the print quality in metal additive manufacturing by analyzing porosity formation and surface roughness, especially for overhanging structures. This work presents the first known study utilizing hybrid additive manufacturing as a machining-based sensor to measure mechanical properties. Also, this work investigates the effects of print process parameters within Lumex CAM (Matsuura Lumex Avance-25) on porosity formation and surface topography. The results indicated that the variation of the net cutting specific energy correlated with the residual stress in the first millimeter as well as the microhardness across the build. X-ray CT results and laser profilometry revealed that porosity formation and surface topography were controlled by the melt pool dimensions and the print strategy. In addition, one mechanism explaining the alignment of pores across the build was the position of the recoater according to the gas flow during printing.
Advisor: Michael P. Sealy
Comments
A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Mechanical Engineering and Applied Mechanics, Under the Supervision of Professor Michael P. Sealy. Lincoln, Nebraska: December, 2021
Copyright © 2021 Kossi Loic Mawunyegan Avegnon