In situ monitoring of direct laser metal deposition of a nickel-based superalloy using infrared thermography
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ORIGINAL ARTICLE
In situ monitoring of direct laser metal deposition of a nickel-based superalloy using infrared thermography Marco Mazzarisi 1 & Sabina Luisa Campanelli 1
&
Andrea Angelastro 1 & Fania Palano 2 & Michele Dassisti 1
Received: 15 May 2020 / Accepted: 2 November 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract Metal additive manufacturing is growing its impact on high-tech industrial sectors so far. The capability to recover and repair worn components, with costs that are gradually more affordable, is giving a boost to the development of these technologies. The direct laser metal deposition (DLMD) technology is taking a leading role in this domain. Manufacturing components, with high mechanical properties, require a careful process design and a continuous control. The monitoring of the thermal field thus assumes a crucial role in processes in which high-power sources are involved. Thermal treatments influence the microstructure, morphology and the grain size of the depositions indeed, which determine high-performance standards. In this work, an ytterbium fibre laser source was used to build singletrack depositions of a nickel-based superalloy powder on a substrate of the same material. Temperature field monitoring was performed using a high-frequency (100 Hz) IR thermal camera, allowing an accurate monitoring of peeks temperature, thermal cycles and thermal gradients. Thermal data and process parameters were compared with metallographic analysis to capture the relation between the geometrical and microstructural characteristics of clads. The study focuses on the influence of the powder feed rate and energy density on thermal parameters. An innovative approach to the solidification map method, commonly implemented with numerical simulations of welding and additive manufacturing, has been successfully applied to experimental data giving results consistent with the literature. Keywords Direct laser metal deposition . Nickel-based superalloy . IR thermography . In situ monitoring . Thermal camera . Thermal gradient
1 Introduction The direct laser metal deposition (DLMD) is an innovative technology used typically to repair and/or manufacture metal components. The DLMD uses a laser beam focused on a substrate in order to create a melting pool in which the powder stream is carried in by means of an inert gas flow, which is coaxial or lateral with respect to the laser beam, to create a thick clad. In this process, the designed geometry is obtained layer by layer, through a series of adjacent depositions, as programmed in a tool path compiled by a specific CAM * Sabina Luisa Campanelli [email protected] 1
Department of Mechanics, Mathematics and Management, Politecnico di Bari, Via Orabona, 4, 70125 Bari, Italy
2
ENEA, Centro Ricerche di Brindisi c/o Cittadella della Ricerca, S.S.7 Appia km 706, 72100 Brindisi, Italy
software [1–3]. The capability to produce thin-walled metal parts and complex geometries is one of the key features of the technology. The DLMD is
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