Constant stress creep and apparent activation energy analysis of a Ni-base superalloy between 1023 and 1123 K

New steady stale creep data of Inconel 738 Ic at 1023, 1073 and 1123 K at stresses between 250 and 580 MPa are reported. At each temperature analyzed, two regions of different slope in the log sigma vs log epsilon diagram were obtained related to different deformation mechanisms. The data were interpreted in terms of the Dorn's relationship and the Brown and Ashby's approach. Apparent activation energy were also measured and analyzed considering the variation with temperature of all the parameters of the Dorn's equation. This kind of approach could explain the high values of apparent activation energies obtained in precipitation hardened alloys.