Development of a surface engineering strategy to quantify the sensitivity of surface integrity features in fatigue performance

Abstract

The fatigue performance of a metallic component is strongly correlated with several surface integrity features (surface roughness, residual stresses, microstructure). It is commonly characterised using ISO tests. However, conventional procedures for manufacturing fatigue samples influence all the surface integrity features simultaneously. So, standard fatigue testing procedures do not discriminate between each feature’s sensitivity. This paper aims to show how an advanced combination of various processes (finish turning, belt finishing, roller burnishing) leading to complementary process signatures determines which surface integrity features are the most sensitive and how two features can be coupled. This methodology is applied to a martensitic stainless steel 15-5 PH (precipitation-hardening). It highlights that this steel is very sensitive to the presence of a nanosized white layer and that there is a synergy effect by combining a thick compressive layer and a very low surface roughness.