Microstructural Changes of 22Cr-9Mo-3Fe-4Nb Ni-Base Superalloy during Creep

2017 Korean Journal of Metals and Materials  
A new Ni based superalloy is considered as bucket material because of high fatigue resistance with fine grain. However a bucket is usually exposed to high temperature for a long time, so creep rupture tests were conducted to understand the microstructure evolution during creep deformation under various stresses at temperatures of 566, 593, 621, 649 and 670 ℃. The hardness applied to the crept specimen of these alloys increased until the value of LMP reached 25, and decreased while the value of
more » ... MP exceeded 25. The microstructure analysis with TEM, SEM and OM were conducted on ruptured specimen to observe the changes of γ″ morphology, carbides, and fracture mode. As a result of investigating microstructural changes and creep properties, it can be concluded that the effect of grain size on creep properties is dominant regardless of the size of γ″. † (
doi:10.3365/kjmm.2017.55.7.486 fatcat:7om65vu3qbglrhn5q7h6zgaphe