Creep data analyses of a columnar-grained nickel-base superalloy by conventional and Β-envelope methods

Creep-rupture properties of a columnar-grained nickel-base superalloy have been evaluated over a wide temperature range (1033 to 1311 K) and stress levels (80 to 850 MPa). Creep data analyses based on the conventional approach as well as on a new graphical method—the Β-envelope method (Ref 1)—have been carried out for creep strain and life estimation purposes. The relation between minimum creep rate of the alloy with the applied stress obeys simple power law, whereas the rupture data of the alloy fits well to the Larson-Miller parameter. Also, the Monkman-Grant relation between the minimum creep rate and the rupture life produces a trend with some degree of scatter in the data. The latter relation in its generalized form by the Β-envelope method exhibited the best correlation with significantly reduced scatter in the data.