摘要：In this work, an ultrasonic fatigue technique is presented to study the fatigue behavior on an austenitic steel at high temperatures under fully reverse loading (R=-1) in the lifetime range from 105 to 109 cycles. This material is employed in internal combustion engine valves. To carry out the fatigue tests at high temperatures, an induction coil heating equipment was employed to achieve temperatures as high as 600C and 700C on the specimens. Since Young modulus is a function of temperature, its value changes when the specimen is heated. We analyzed with a numerical methodology (finite element method, FEM), the effects of the variation in the Young modulus due to temperature from the measurement of the ultrasonic resonance frequency. Thermal, thermo-mechanical and modal analysis by FEM was used for designing the specimens at test temperatures. The commercial software was employed for the numerical simulations.
