Direct observation of crack formation mechanisms with operando Laser Powder Bed Fusion X-ray imaging

A quantitative study of thermal cycling along the build direction of Ti-6Al-4V produced by laser powder bed fusion

“…During past years, several in situ synchrotron X-ray diffraction and imaging experiments have been performed to study the microstructure evolution during metal 3D printing. The melt pool dynamics can be studied in detail by fast radiography experiments [26][27][28][29][30][31]. The evolution of the crystallographic phases, stress and temperature has been investigated by in situ X-ray diffraction [28,[32][33][34][35].…”

Operando tomographic microscopy during laser-based powder bed fusion

“…In particular, operando techniques for LPBF process studies have been developed worldwide at synchrotrons, providing direct "live" insight into this complex manufacturing process 33 . This is re ected by numerous recent publications from such facilities, as the Swiss Light Source (SLS) [34][35][36][37] , Stanford Synchrotron Radiation Light source (SSRL) [38][39][40] Diamond Light Source (DLS) [41][42][43][44] , European Synchrotron Radiation Facility (ESRF) 44,45 and the Argonne National Laboratory's Advanced Photon Source (APS) 33,46 . Operando and in situ diffraction studies performed during LPBF allow for observation of phase transformations occurring prior and after melting and solidi cation as well as evaluation of temperature pro les and cooling rates 35 34,37,47 , while in situ X-ray radiography provides invaluable knowledge about melt pool dynamics [47][48][49][50] and formation of defects such as cracks 37,51 and porosity 49,52−54 .…”

“…This is re ected by numerous recent publications from such facilities, as the Swiss Light Source (SLS) [34][35][36][37] , Stanford Synchrotron Radiation Light source (SSRL) [38][39][40] Diamond Light Source (DLS) [41][42][43][44] , European Synchrotron Radiation Facility (ESRF) 44,45 and the Argonne National Laboratory's Advanced Photon Source (APS) 33,46 . Operando and in situ diffraction studies performed during LPBF allow for observation of phase transformations occurring prior and after melting and solidi cation as well as evaluation of temperature pro les and cooling rates 35 34,37,47 , while in situ X-ray radiography provides invaluable knowledge about melt pool dynamics [47][48][49][50] and formation of defects such as cracks 37,51 and porosity 49,52−54 . Thanks to the rapid progress in detector and synchrotron development, X-ray radiography bene ts from a high temporal resolution allowing frame rates up to 400 kHz 31,50 suitable for observing uctuations of the keyhole, sputtering or powder particles ejection 55 .…”

Miniature laser powder bed fusion system for in situ synchrotron x-ray micro-computed tomography experiments at the European Synchrotron Radiation Facility

“…High-speed optical cameras were first used for in situ process monitoring to estimate the density of spatters, [1][2][3][4][5] but this approach suffers from a major limitation since only the top surface can be observed. This limitation was recently overcome with the development of different L-PBF replicators [6][7][8][9][10] allowing time-resolved x-ray images to be collected during 3D printing. MHz-frame rate x-ray radiography has recently enabled to shed light on the fundamental mechanisms involved in the melt pool dynamics while melting a single track.…”

“…MHz-frame rate x-ray radiography has recently enabled to shed light on the fundamental mechanisms involved in the melt pool dynamics while melting a single track. 6,[9][10][11][12][13][14][15] Different materials, such as Ti-alloys, 7,9,15,16 Fe-alloys, 11,13,14 Ni-alloys, 10 Review of Scientific Instruments ARTICLE scitation.org/journal/rsi and also Al-alloys, 8,11,12,15 have been characterized using such an approach. Even more recently, L-PBF replicators offering the possibility to monitor the process using x-ray diffraction to collect information regarding phase transitions were also developed.…”