Superalloys 2024: General Session 10: Additive Manufacturing II
Program Organizers: Jonathan Cormier, ENSMA - Institut Pprime - UPR CNRS 3346
Wednesday 8:45 PM
September 11, 2024
Room: Exhibit Hall
Location: Seven Springs Mountain Resort
Session Chair: Nathalie Bozzolo, Safran; Stephane Forsik, Carpenter Technology Corporation
8:45 PM
A Correlative In-situ, Ex-situ & 3D Analysis of Static Recrystallisation in a New Superalloy for 3D-printing: Yuanbo Tang1; Anh Hoang Pham2; Satoshi Utada1; Jieming Zhang1; Yuhan Zhuge1; Shigekazu Morito2; Kazuto Arakawa2; D. Graham McCartney1; Roger Reed1; 1University of Oxford; 2Shimane University
By making particular use of high temperature confocal laser scanning microscopy, static recrystallisation is studied correlatively both in-situ and ex-situ in an as-fabricated superalloy made by laser-powder bed fusion (L-PBF). In this way, insights are gained into important recrystallisation phenomena with direct observations made – for the first time in this class of material – of phenomena such as nucleation of recrystallisation, subsequent grain growth, jerky flow of boundaries due to pinning and twin formation. The nucleation process – requiring strain-free lattice to be created by grain boundary migration – is visualised and its role in limiting the kinetics of recrystallisation is elucidated. Moreover, it is demonstrated that boundary mobility is initially prevented by Smith-Zener pinning due to a fine dispersion of secondary phases but also with a role played by solute drag caused by cellular micro-segregation. With increasing annealing time, the retarding pressure reduces due to carbide coarsening and/or dissolution as well as matrix compositional homogenisation, eventually allowing recrystallisation to take place. Further work will allow rich quantitative datasets to be gained which will allow for the testing of recrystallisation models.
9:10 PM
Near Single-crystalline CMSX-4 Superalloy Builds with Laser-directed Energy Deposition (L-DED) using Model-informed Experiments: Swapnil Bhure1; Divya Nalajala1; Abhik Choudhury1; 1Indian Institute of Science
Manufacturing of single-crystalline Ni-base superalloy blades is extremely complex due to the intricate geometry of the blade profile and cooling channels. Additive manufacturing provides an excellent alternative to the classical Bridgman solidification, as it significantly reduces the number of steps involved. However, since the solidification conditions differ greatly, it is crucial to identify appropriate process parameters to ensure defectfree single-crystalline builds. In this paper, we present a complementary approach between experiments and numerical simulations of the melt pool shapes that enables the identification of the process parameter window for directional growth. Further, an incremental process optimization approach is developed that allows the gradual reduction of grains, creating conditions for epitaxial growth. Finally, it is revealed that the proposed strategy for achieving single-crystal growth conditions leads naturally towards crack-free builds of rods with the CMSX-4 alloy.
9:35 PM
Eutectic Superalloys for Laser Powder Bed Fusion: Katerina Christofidou1; Jonathon Markanday2; Alison Wilson2; Ed Pickering3; Nicole Church2; James Miller2; Nicholas Jones2; Neil Jones4; Howard Stone2; 1University of Sheffield; 2University of Cambridge; 3University of Manchester; 4Rolls-Royce
Due to the small freezing range of eutectic alloys, the Cotac-type alloys might be viable alternatives to conventional Ni-based superalloys when processed through additive manufacturing. Laser-pass assessment reveals that both Cotac-74 and Cotac-744 display improved cracking resistance when compared to the conventional Ni-based superalloy CM247LC. During laser powder bed fusion Cotac-74 displayed the highest cracking resistance, with no microcracking detected in the as-built or heat-treated microstructure. The promising results presented for Cotac-74 highlight the possible use of this alloy for the additive manufacturing of high-temperature aerospace components.