抄録
Out-of-phase thermo-mechanical fatigue (TMF) tests and low cycle fatigue (LCF) tests were performed on Nibase single crystal superalloy, CMSX-4. LCF tests were performed at 800℃ and TMF tests were performed under 200-800℃ out-of-phase conditions. In both tests, tests were performed under fully reversed, total mechanical strain controlled conditions, and specimens whose axial orientations were [100] and [011] were used for evaluating the influence of crystal orientation on deformation behavior and fracture life. As the results, deformation behavior and fracture life were strongly influenced by specimen crystal orientation and temperature-strain range. To evaluate these effects, γ/γ' unit-cell finite element (FE) analysis were performed. Simulations revealed that even if macroscopic inelastic strains in hysteresis loops were small, inelastic strains were clearly occurred in γ phase microscopically. And the simulations under TMF conditions revealed that microscopic deformation shows tension/compression asymmetry and these asymmetric deformation causes ratcheting deformation in γ and γ' phases.
