Surface integrity is a subject covering the description and control of the many possible alterations produced in the surface of a component during manufacturing. Surface integrity is evaluated by measuring the influence of machined surface layers on component reliability. This is accomplished primarily through fatigue testing under both low-cycle and high-cycle conditions. Considerable data have been developed permitting definition of characteristic changes in fatigue strength of a variety of high-strength structural alloys as a function of several different metal removal methods and also variations within these methods.
High-cycle fatigue data have been developed in the cantilever bending mode at temperatures ranging from ambient to 1400 F. Low-cycle fatigue data have been obtained in four-point bending over the same temperature range following the development of a specialized testing technique.
Data are presented showing fatigue behavior of Inconel 718, René 80, and René 95 using specimens finished by variations of grinding, turning, electrochemical machining, and electrical discharge machining.