Mapping of distortion in EB-PBF produced components and its remedies
2022 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE credits
Student thesis
Abstract [en]
Metal components that would not have been possible before are made possible to be produced using Additive manufacturing (AM). AM is no longer used only for prototyping instead can be successfully employed to produce actual functional metal components. VBN Components AB, a material development company, is founded in 2008 and is working in the field of AM producing functional parts used in wear-resistant applications. VBN Components AB has achieved this by developing several different highly alloyed metal powders called the Vibenite® series that are processed using AM. High carbide content (1-65 vol. %) that varies in each Vibenite® material makes these materials highly wear-resistant. Vibenite® materials require high processing temperatures which makes the EB-PBF process suitable to manufacture components in near-net-shape. Manufacturing components using such highly alloyed material is a challenging task as sometimes defects occur due to specific part geometry, build settings or melt strategy that leads to the loss in dimensional accuracy called distortion. In the current study, the phenomenon of distortion is investigated in Vibenite® 280 components. Different strategies are suggested in the design of the build preparation to reduce such distortion effects. The first part of the study revealed that the printed hole diameter comes out to be smaller in diameter in comparison to the corresponding design diameter. In other words, the material surrounding the hole feature shrinks less than the other surfaces of the component geometry. The difference in the material shrinkage around holes and other surfaces of the parts is due to the differential in the rate of conductive heat transfer of different part surfaces to the surrounding sintered powder. A formula has been presented as a result of this study to compensate for variations in hole sizes during the CAD process. The second part of the study addresses the phenomenon of warpage. When there are large continuous overhang melt areas in the component, significantly more energy is required for melt. During the cooling, non-uniform heat dissipation results in a non-uniform strain in the melt layer. This causes deformation which results in the curling up of flat overhang surfaces. Different strategies have been designed and tested to reduce the effect of warpage. A new type of support is proposed with good results to mitigate the warpage.
Place, publisher, year, edition, pages
2022. , p. 44
Series
MATVET Materialteknik
Keywords [en]
Electron Beam Melting, Additive Manufacturing, Laser powder Bed Fusion, Powder Metallurgy, Powder Bed Fusion Processes, Standard Tessellation Language, Hot Isostatic Pressing, Electron Beam – Powder Bed Fusion, Computer-Aided-Design, Shrinkage Compensation Factor, Diameter Shrinkage Compensation Factor, Updated Diameter Shrinkage Compensation Factor
National Category
Materials Engineering
Identifiers
URN: urn:nbn:se:uu:diva-488983OAI: oai:DiVA.org:uu-488983DiVA, id: diva2:1713369
External cooperation
VBN Components AB
Supervisors
Examiners
2022-12-132022-11-242022-12-13Bibliographically approved