FCP Report No. 132

An Investigation into Isothermal and Thermo-mechanical Fatigue Damage at Elevated Temperatures


Mark L. Karasek



Thermo-mechanical fatigue problems are encountered in many engineering applications. Temperature and load cycling may occur in turbine blades, piping, pressure vessels, railroad wheels due to brake shoe action and other components which experience high temperatures in service. Fatigue damage (crack initiation and growth) under thermo-mechanical loading has not been examined as extensively as fatigue damage under isothermal loading. As a result, while isothermal tests at high temperatures have been performed and results are available for many materials, conditions exist where isothermal data fails to adequately predict thermo-mechanical damage. Further work is needed to establish the differences in material behavior for the two cases and provide a better understanding of the problem.

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