Thermomechanical Fatigue Behavior of a Superalloy
Thermomechanical Fatigue Behavior of a Superalloy
A thermal-mechanical fatigue test facility is described to study the stress-strain behavior and fatigue damage under anisothermal conditions of materials for gas turbine blading applications. Hollow specimens are heated by a radiation furnace; a microcomputer is used to generate simultaneous strain and temperature signals and tests are conducted under closed-loop control of axial strain. A typical mechanical strain-temperature loop has been used from 600 to 1050°C (873 to 1323 K) with peak strains at intermediate temperatures. Application to IN 100, a nickel base superalloy, is reported. Crack initiation and early crack growth are shown which are deduced from a plastic replication technique. The role of oxidation has been emphasized and the life of thermal mechanical fatigue specimens was found to be in good agreement with low-cycle fatigue results at 1000°C (1273 K).
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