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 M 23 C 6 where Mo and Ti elements emigrated and merged with small MC/M 23 C 6 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/M 23 C 6 , 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.