An Improved Empirical Constitutive Model for γ'-Strengthened Nickel-Based Superalloys

摘要

Advanced superalloys were developed for high performance systems such as jet engines, internal combustion engines and gas turbines. Nickel-based superalloys are strengthened by the γ'-phase, through various mechanisms, such as lattice parameter mismatch, coherent strain, or anti-phase boundary. Due to the changing of lattice parameters of γ-phase and γ'-phase at various temperatures, the deformation mechanisms perform anomalously. The objective of this paper is to develop a constitutive model for nickel-based superalloys, which could be further implemented in finite element analysis. In order to derive an accurate constitutive model, strain hardening function, thermal sensitivity function, and flow softening function were determined. Also, piecewise method was applied as a function of the temperature ranges. The novel constitutive model proposed for superalloys was compared with material testing data (flow stress) and a good agreement was found for a temperature range from 294K to 1144K.