Shot peening, a commonly used method of fatigue and surface enhancement, is a critical process in many of the components in the aerospace industry. When it comes to small holes and/or slot geometries in these components, the process can become a challenge when these features are smaller than a conventional size Almen strip. In these cases, a decision must be made about how to process this type of geometry. Oftentimes, the method to apply the shot peen process is already defined in a process specification or part print so we must adhere to that method. If a method is not defined however, there are a few different strategies we can use to apply the shot peen process to the hole/slot geometry as accurately as possible. These methods involve using full size Almen strips, partially shaded strips and mini sized Almen strips. Along with the various strip configurations, we will use a conventional nozzle peening process as well as deflector lance peening processes to the strips and then to coupons. By manufacturing identical coupons made from a commonly used aerospace alloy, we can apply each of these different shot peen strategies which are described in this study. After shot peening the coupons, they will be sent for x-ray diffraction (XRD) analysis. This will allow us to compare the compressive residual stress (CRS) profiles of each method to discern if there are any measurable differences between the methods.
James T. Hoffman (Wed,) studied this question.