seyedebrahim moussavi torshizi - Department of mechanical engineering, Shahid Beheshti University
mohammad hamisi - Deparrmenr of mechanical engineering, Shahid Beheshti University

The microstruetural changes in an austenite stainless steel exposed to temperatures in the 750 °C to 950 °C range for 72 hours were investigated. The purpose of this study is to investigate the effect of structural changes on natural frequencies aI1d damping coefficients of samples of AISI 310S stainless steel. Intense carbide precipitation occursin all conditions. Sigma phase precipitation nucleates at the grain boundaries and becomes more intense with the increase of time and temperature. Sigma phase and chromium carbides cause severe sensitization, but healing is observed in specimens aged at 750 °C, 850 °C and 950 °C. Time to healing decreases with the increase of agingtemperature. With increasing structural changes. it was found that the natural frequencies of the ten modulus increase significantly. These promising results are the elaboration of a non-destructive new method for estimating the remaining life for components of different generations under long-term overheated operation conditions.

Damping Capacity, Aging, Microstructural change. Natural Frequency. AISI 3105