Miniature Mechanical Testing to Infer Damage from Accidental and Complex Thermal Exposure for Single Crystal Superalloys

Mechanical testing featuring miniaturized specimens are resource-efficient alternative to standardized testing that can offer unparalleled insights. In this work, the established electro-thermal mechanical testing procedure was used for evaluating potential damage to microstructure given by unexpected thermal/mechanical load. Two conceptualized scenarios were considered. The first case concerns property deterioration given long-term complex exposure of temperature and stress, using specimens directly extracted from turbine blades. The second case concerns an ‘accidental’ solution treatment at near-incipient melting temperature. Quasi-static and dynamic tests were carried out to pick up potential property change against the reference condition. For the reference microstructure, low cycle fatigue was shown successful in yielding reproducible fatigue life and pick up location-dependent strain hardening response between suction vs. pressure side of a turbine blade. The property difference, given each scenario, was benchmarked accordingly and rationalized with microscopic evidence.