Creep Lifetime Prediction for Polycrystalline Nickel-Based Superalloys

Creep lifetimes of polycrystalline nickel (Ni) based superalloys with given chemical compositions were predicted using the Larson-Miller parameter (LMP) and chemical composition, which reflects the effects of solid -solution strengthening and precipitation strengthening. Herein, the former effect is denoted as a delta parameter representing the amount of strengthening by multiple elements; the latter effect is a lattice misfit between gamma and gamma' phases: xi. These parameters respectively generate vertical and parallel translations of an LMP plot. The solid solution affects strengthening, i.e., vertical translation. The precipitate affects heat resistance in the alloys, i.e., parallel translation. After the trends were formulated in the first order, the amount of translation was evaluated quantitatively. The prediction worked well in the solid -solution strengthened Alloy 600 and Alloy 617 and in the solid -solution strengthened and precipitation strengthened gamma + gamma' TMP alloy. Creep lifetimes of Ni-based alloys and superalloys can be predicted well using the simple formulae.