Surface Integrity – Definition and Importance in Functional Performance

This chapter presents an overview of the nature of the surface that results from manufacturing processes, as this nature has long been recognized as having a significant impact on the product performance, longevity and reliability. Surface alterations may include mechanical, metallurgical, chemical and other changes. These changes, although confined to a small surface layer, may limit the component quality or may, in some cases, render the surface unacceptable. A basic understanding of the changes in the condition of the surface is very much required if improvement in product quality is to be attained. Surface integrity (SI) reveals the influence of surface properties and condition upon which materials are likely to perform. It has long been known that the method of surface finishing and the complex combination of surface roughness, residual stress, cold work, and even phase transformations strongly influence the service behavior of manufactured parts as fatigue and stress corrosion.