Understanding of process and material behaviours in additive manufacturing of Invar36/Cu10Sn multiple material components via laser-based powder bed fusion
Journal
Additive Manufacturing
Journal Volume
37
Start Page
101683
ISSN
22148604
Date Issued
2021-01
Author(s)
Abstract
Bimetallic components and functionally graded material (FGM) samples manufactured by additive manufacturing reported in previous publications generally have macro defects such as insufficient powder melting, cracking, and porosity at the interfaces of dissimilar materials. There is little understanding of the causes of these defects. The motivation of this research was to explain why the un-melted particles and cracks were always present at the materials' interface when using laser-based powder bed fusion (PBF-LB) to process powder mixtures composed of two materials with significant different thermo-physical properties. In this study, the influence of laser volume energy density (VED) and material composition ratio on the melting status of laser-processed powder layers was investigated both experimentally and theoretically. Experimental results show that VED, sufficient to melt the high melting point Invar36 alone, is insufficient to melt the Invar36/Cu10Sn mixture. This phenomenon is because Cu10Sn copper alloy has lower laser beam absorptivity, higher thermal conductivity and lower melting temperature. When the Cu10Sn powder partially covers the surface of a powder layer, the laser energy absorption is reduced. Its high thermal conductivity causes heat to dissipate more quickly. These two factors make it difficult for Invar36 located below Cu10Sn to reach its melting point. Computational fluid dynamic and discrete element method simulation is conducted to understand this phenomenon, and it shows that increasing VED can improve the melting of the Invar36/Cu10Sn powder mixture.
Subjects
Additive manufacturing
Bimetallic material
Cu10Sn
Functionally graded material
Invar36
Laser volume energy density
Laser-based powder bed fusion
SDGs
Publisher
Elsevier B.V.
Type
journal article