Multi-physics modeling of single/multiple-track defect mechanisms in electron beam selective melting. (1st August 2017)

• Record Type: Journal Article
• Authors: Yan, Wentao; Ge, Wenjun; Qian, Ya; Lin, Stephen; Zhou, Bin; Liu, Wing Kam; Lin, Feng; Wagner, Gregory J.
• Is Part Of: Acta materialia. Volume 134(2017)
• Page Start: 324
• Page End: 333
• Publication Date: 2017-08-01
• Subjects: Electron beam selective melting -- Powder-scale modeling -- Computational heat transfer and fluid dynamics -- Single track -- Balling effect and nonuniformity; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2017.05.061
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: Metallic powder bed-based additive manufacturing technologies have many promising attributes. The single track acts as one fundamental building unit, which largely influences the final product quality such as the surface roughness and dimensional accuracy. A high-fidelity powder-scale model is developed to predict the detailed formation processes of single/multiple-track defects, including the balling effect, single track nonuniformity and inter-track voids. These processes are difficult to observe in experiments; previous studies have proposed different or even conflicting explanations. Our study clarifies the underlying formation mechanisms, reveals the influence of key factors, and guides the improvement of fabrication quality of single tracks. Additionally, the manufacturing processes of multiple tracks along S/Z-shaped scan paths with various hatching distance are simulated to further understand the defects in complex structures. The simulations demonstrate that the hatching distance should be no larger than the width of the remelted region within the substrate rather than the width of the melted region within the powder layer. Thus, single track simulations can provide valuable insight for complex structures. Graphical abstract: