One of the most used manufacturing processes for producing mechanical components with complex geometries in a short time is additive manufacturing (AM). For this reason, thanks to the application of these kind of processes, it is possible to simulate the presence of simulated defects with a particular shape inside the produced material, that represents a powerful tool in the field of non-destructive controls to calibrate the technique and establish the limit in a quantitative way. To do this, without AM, the investigation concerns defects like flat bottom holes, with a geometry and a behavior very far from a real defect. This work is focused on the application of active thermography as non-destructive technique to assess the quality of AISI 316L metal samples produced by means of laser powder bed fusion (L-PBF) process. It is known that one of the most widespread and common defects in steel materials is porosity, diffuse and localized, due to sudden and unexpected changes in process conditions. From a thermal point of view, this type of defect is very far from the one normally simulated with non-destructive techniques, that are flat bottom holes or delaminations. More in general, sub-superficial defects, like porosities, affect the quality of the signal and the detection limit. For this reason, a complete experimental plan has been carried out to print sub-superficial spheres of different size (depth and diameter) in different specimens, for a total of about 150 defects, including replications at fixed nominal aspect ratio and shape factor. In particular, these spheres have non-melted powder of the same material inside. A reflection set-up with two flash lamps and a MWIR-cooled sensor has been used to perform different tests and to define the limits and the advantages of the proposed technique. To improve the quality of the thermal signal and the signal-to-noise ratio, post-processing algorithms have been used to process the raw thermal data. The study is a preliminary research activity aimed to calibrate the technique for the quantitative estimation of porosity in steel components.
Detection Analysis for Sub-Superficial Defects in Additive Manufactured Metal Samples by Means of Flash Thermography / D'Accardi, E.; Palumbo, D.; Errico, V.; Fusco, A.; Angelastro, A.; Addante, G. D.; Galietti, U.. - (2023), pp. 43-54. (Intervento presentato al convegno Conference and Exposition on Experimental and Applied Mechanics, 2022 tenutosi a Pittsburgh, PA - United States nel 13-16 june 2022) [10.1007/978-3-031-17475-9_7].
Detection Analysis for Sub-Superficial Defects in Additive Manufactured Metal Samples by Means of Flash Thermography
D'Accardi E.
;Palumbo D.;Errico V.;Fusco A.;Angelastro A.;Addante G. D.;Galietti U.
2023-01-01
Abstract
One of the most used manufacturing processes for producing mechanical components with complex geometries in a short time is additive manufacturing (AM). For this reason, thanks to the application of these kind of processes, it is possible to simulate the presence of simulated defects with a particular shape inside the produced material, that represents a powerful tool in the field of non-destructive controls to calibrate the technique and establish the limit in a quantitative way. To do this, without AM, the investigation concerns defects like flat bottom holes, with a geometry and a behavior very far from a real defect. This work is focused on the application of active thermography as non-destructive technique to assess the quality of AISI 316L metal samples produced by means of laser powder bed fusion (L-PBF) process. It is known that one of the most widespread and common defects in steel materials is porosity, diffuse and localized, due to sudden and unexpected changes in process conditions. From a thermal point of view, this type of defect is very far from the one normally simulated with non-destructive techniques, that are flat bottom holes or delaminations. More in general, sub-superficial defects, like porosities, affect the quality of the signal and the detection limit. For this reason, a complete experimental plan has been carried out to print sub-superficial spheres of different size (depth and diameter) in different specimens, for a total of about 150 defects, including replications at fixed nominal aspect ratio and shape factor. In particular, these spheres have non-melted powder of the same material inside. A reflection set-up with two flash lamps and a MWIR-cooled sensor has been used to perform different tests and to define the limits and the advantages of the proposed technique. To improve the quality of the thermal signal and the signal-to-noise ratio, post-processing algorithms have been used to process the raw thermal data. The study is a preliminary research activity aimed to calibrate the technique for the quantitative estimation of porosity in steel components.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
