Micromagnetic-Based Fatigue Life Prediction of Single-Lip Deep Drilled AISI 4140

Non-destructive testing based on micromagnetic techniques, for example magnetic Barkhausen noise analysis, are quick and reliable possibilities to detect and classify material parameters like hardness and residual stresses. High-strength steels, like AISI 4140 (42CrMo4 + QT), are commonly used for highly dynamically loaded parts. Increasing requirements on weight, performance and efficiency of automotive industry claim increasing demands on material properties. The aim of this study is to evaluate the surface conditions of deep drilled round specimens due to drilling parameters and to predict the resulting fatigue strength by micromagnetic measurements. Furthermore, modified process parameters should enhance fatigue life without the need for expensive processing steps, e.g. autofrettage.