Influence of the γ/γ′ misfit on the strain-age cracking resistance of high-γ′ Ni and CoNi superalloys for additive manufacturing

DOI: 10.1007/978-3-031-63937-1_84

Authors: Stephane A. J. Forsik (Carpenter Technology Corporation) , Austin D. Dicus (Carpenter Technology Corporation) , Gian A. Colombo (Carpenter Technology Corporation) , Tao Wang (Carpenter Technology Corporation) , Mario E. Epler (Carpenter Technology Corporation) , Eamonn T. Connolly (Diamond Light Source) , Jiraphant Srisuriyachot (University of Bath) , Alexander Lunt (University of Oxford) , Ning Zhou (Carpenter Technology Corporation)
Co-authored by industrial partner: Yes

Type: Conference Paper
Conference: Superalloys 2024
Peer Reviewed: Yes

State: Published (Approved)
Published: August 2024
Diamond Proposal Number(s): 31442

Abstract: A series of new printable Ni and Co–Ni high γ′ superalloys designed for additive manufacturing have been evaluated for strain-age cracking (SAC) resistance. Printability studies and heat treatment experiments were conducted to identify processing windows and characterize the overall resistance to SAC. High-resolution synchrotron X-ray diffraction experiments were performed to measure the γ and γ′ lattice parameters as a function of the temperature. All the superalloys tested were found to have a positive γ/γ′ misfit at room temperature which decreases as the temperature increases. The misfit of a SAC-prone alloy, 247LC, decreases rapidly and turns negative at about 600 °C, whereas the misfit of superalloys with intermediate resistance to strain-age cracking remains slightly positive. In the three most SAC-resistant superalloys, the misfit remains larger than 0.05% until at least 883 °C. The results show that a critical aspect for designing SAC-resistant alloys is ensuring that the misfit between γ and γ′ remains positive at all temperatures to generate compressive stresses on grain boundaries. Furthermore, the work also highlights a critical positive misfit value of 0.05% to prevent cracking.

Diamond Keywords: Additive Manufacturing; Alloys

Subject Areas: Materials, Engineering


Instruments: I11-High Resolution Powder Diffraction

Added On: 25/08/2024 08:37

Discipline Tags:

Materials Engineering & Processes Materials Science Engineering & Technology Metallurgy

Technical Tags:

Diffraction