The correlated mechanism of creep fracture and microstructure evolution for precipitated Nimonic 263 superalloy welding joint

Abstract

The correlated mechanism of microstructural evolution and creep failure of N263 weld joint was studied in this paper. Results show that the creep failure presented in weld metal (WM), which initiated in the solute poor area near coarsened MC and/or M₂₃C₆ where Mo and Ti elements emigrated and merged with small MC/M₂₃C₆ to larger ones. Moreover, the crack propagated along the primary dendrite wall and second dendrite arm in which Mo and Ti are poor due to the precipitation and coarsening of MC/M₂₃C₆, which is caused by the different partition coefficient of main alloy elements during non-equilibrium solidification. However, the transition of decomposed MC to fine η phase during creep in WM is not responsible to crack initiation and propagation.

KEYWORDS:

• Ni-based superalloys
• creep fracture
• microstructural evolution
• elements segregation
• welding joint

Acknowledgements

The authors gratefully acknowledge the financial support by the National Natural Science Foundation of China (No. 51675336) and the experimental supports by Instrumental Analysis Center of SJTU.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors gratefully acknowledge the financial support by the National Natural Science Foundation of China [grant number 51675336] and the experimental supports by Instrumental Analysis Center of SJTU.