Experimental Analysis of the Interaction of “Hot” and “Cold” Volume Elements during Thermal Fatigue of a Cooled Component Made from AISI 3161 Steel

Abstract

Abstract Start-stop and load change procedures of combustion engines result in inhomogenous and instationary temperature fields, which induce cyclic mechanical loadings, e. g., in solid and cooled turbine blades and vanes. The present study shows results of so-called “complex thermal-mechanical fatigue” (CTMF) tests carried out with a two specimen testing system in order to simulate the interaction of the “hot” outer and the “cold” inner side of a cooled turbine blade. The test samples were made from the austenitic steel AISI 316 L. Specimen 1 represents the “hot” and specimen 2 the “cold” side of the blade, respectively. Both specimens were loaded by individual thermal cycles with closed loop control of the temperature. The mechanical interaction of the “hot” and the “cold” side was simulated by keeping the total strains of both specimes at identical values and keeping the sum of the forces at a value of zero at every moment throughout the tests. The results are discussed on the background of the microstructures resulting from the individual loadings of specimen 1 and 2.