Direct observation of crack formation mechanisms with operando Laser Powder Bed Fusion X-ray imaging
Hossein Ghasemi‐Tabasi, Charlotte de Formanoir, S. Van Petegem, Jamasp Jhabvala, Samy Hocine, Éric Boillat, Navid Sohrabi, Federica Marone, Daniel Grolimund, H. Van Swygenhoven, Roland E. Logé
Abstract
Laser powder bed fusion (L-PBF) is a versatile additive manufacturing process that can print geometrically complex metal parts for a variety of applications. However, poor control of defect formation during processing hampers its widespread industrial adoption. Many materials suffer from a high crack susceptibility during L-PBF, which results in degraded mechanical properties, and is an obstacle to the certification of critical parts. In order to unveil the mechanisms of crack formation in a prone-to-cracking nickel-based superalloy, we employ high-speed synchrotron X-ray imaging in combination with a miniaturized L-PBF set-up that reproduces real processing conditions. This unique set-up provides operando imaging of crack formation during L-PBF. Complementary post-mortem inspection of crack morphology and thermal simulations supported by operando X-ray diffraction-based measurements of the temperature evolution allow to identify the cracking mechanism and to differentiate solidification cracking from liquation.