The Effect of Elevated Temperature on the Fretting Fatigue Behavior of Nickel Alloy IN-100

<p>This thesis studied the effect of elevated temperature (600 C) on the fretting fatigue behavior of IN-100. First fretting and plain fatigue S-N curves were determined over a large range of applied stress at an identical stress ratio of 0.03 at 600 C and for fretting tests with a constant contact load. The partial slip condition was verified by using hysteresis between shear force and axial stress techniques. The contact width and the crack initiation location were observed for all of the fretting specimens. The contact widths were consistent with expected values and the crack initiation location was at the trailing edge of contact for all fretting specimens. This study compared its high temperature results to room temperature testing accomplished by this study as well as room temperature data from a previous study using IN-100 with an identical microstructure and another room temperature study of IN-100 with a coarser microstructure. It was found that fretting fatigue reduces the cycles to failure compared to plain fatigue at elevated temperature but a more pronounced reduction was noticed than with room temperature. It was also found that the elevated temperature environment increased the both the plain and fretting fatigue life as compared to similar stress levels at room temperature. The study found that elevated temperature does have an effect on crack initiation and crack propagation as compared to room temperature environment. The higher temperature allowed a longer initiation and crack propagation time which strongly suggests the fatigue life increases with temperature up to 600 C. The creation of oxide films and temperature induced softening or plasticity were both found to act as crack closure mechanisms in another nickel based superalloy IN-718 when fatigued in the high temperature environment. It is therefore likely that these oxidation and plasticity crack closure mechanisms are the reasons for the improved performance at elevated tempera<br>These find</p><p>This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it. This work was reproduced from the original artifact and remains as true to the original work as possible. Therefore you will see the original copyright references library stamps (as most of these works have been housed in our most important libraries around the world) and other notations in the work.</p><p>This work is in the public domain in the United States of America and possibly other nations. Within the United States you may freely copy and distribute this work as no entity (individual or corporate) has a copyright on the body of the work.</p><p>As a reproduction of a historical artifact this work may contain missing or blurred pages poor pictures errant marks etc. Scholars believe and we concur that this work is important enough to be preserved reproduced and made generally available to the public. We appreciate your support of the preservation process and thank you for being an important part of keeping this knowledge alive and relevant.</p>