Three-Dimensional Stress Fields and Slip Systems for Single Crystal Superalloy Notched Specimens

<p>Single crystal superalloys have become increasingly popular for turbine blade and vane applications due to their high strength and creep and fatigue resistance at elevated temperatures. The crystallographic orientation of a single crystal material greatly affects its material properties including elastic modulus shear modulus and ductility. These directional properties along with the type of loading and temperature dictate an anisotropic response in the yield strength creep resistance creep rupture ductility fatigue resistance etc. A significant amount of research has been conducted to determine the material properties in the <001> orientation yet the material properties deviating from the <001> orientation have not been assessed for all cases. Based on the desired application and design criteria a crystal orientation is selected to yield the maximum properties. Currently single crystal manufacturing is able to control the primary crystallographic orientation within 15 of the target orientation which is an acceptable deviation to meet both performance and cost guidelines; the secondary orientation is rarely specified. A common experiment is the standard load-controlled tensile test in which specimens with different orientations can be loaded to observe the material response. The deformation behavior of single-crystal materials under tension and compression is known to be a function of not only material orientation but also of varying microdeformation (i.e. dislocation) mechanisms. The underlying dislocation motion causes deformation via slip and affects the activation of specific slip systems based on load and orientation. The slip can be analyzed by observing the visible traces left on the surface of the specimen from the slip activity within the single crystal material.</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>