Development Of An Invar Strengthened By Ni3Nb-Gamma” Phase Precipitation Suitable For Additive Manufacturing

Authors:

Tiphaine Giroud (1), Philippe Egea (1), Peter Vikner (2), Solange Vivès (2), Charlotte Mayer (1)

1- Aubert & Duval, Les Ancizes-Comps, France

2- Aubert & Duval, Paris, France

Abstract:

Stellar® InvHard is a Nb-enriched Invar designed for additive manufacturing (Laser Powder Bed Fusion). It will be launched on the market in 2023. Compared to Invar 36, Stellar® InvHard exhibits increased mechanical strength while maintaining a low coefficient of thermal expansion. The hardening of this alloy is inspired by superalloys 706 and 718 strengthened by Ni3Nb-γ” phase that precipitates in the austenitic matrix; also containing carbides and Nb-rich δ phase. The precipitation of the γ” phase can be controlled through annealing and aging treatment’s optimization, leading to a hardness in a range: 300-420 HV and the effect on coefficient of thermal expansion increase is limited thanks to the small size of such precipitates. Insights on microstructure and processability will also be presented along to coefficient of thermal expansion.

DOI:

https://doi.org/10.59499/EP235749781