Impacts of Machining Practices on Residual Stresses in Engineering Alloys

This paper is part of a larger study on the effects of different machining practices on the formation of residual stresses at the bulk, grain, and atomic level inside creep resistant titanium-based aerospace alloys. This portion aims to approximate the kinds of residual stresses that are introduced during milling operations on aerospace components. Currently there exist concerns about the understanding and the ability to control residual stresses and distortion while machining aerospace components. The aim of this research is to better understand the relationship between machining methods and the creation of these stresses to allow for the development of better machining and heat treating practices. Samples will be solutionized and fitted with strain gauges before undergoing computer-controlled machining experiments. CNC machining with flood coolant is utilized to minimize unintended variation in cut path and temperature. The effects of differing radial feeds and speeds, during more traditional climb cutting operations and newer peel cutting operations, are investigated, and the resulting distortion and residual stresses in the work piece are examined. Characterization methods include optical light microscopy, SEM, XRD, and EBSD. The results of this study provide insight into the importance of utilizing standardized machining parameters in the machining of aerospace components.