MICRO-INCLUSIONS AND LOADS EFFECT ON METAL FATIGUE: A MODIFIED LIFE ESTIMATION MODEL THROUGH EXPERIMENTAL AND ANALYTICAL INVESTIGATION

Fatigue life calculation of a metal component accounts for different phenomena. External factors, such as load type, as well as internal microstructure, play a major role in determining fatigue failure. The present paper explores the relationship between micro-inclusions in hard steels and fatigue behaviour. Tension- compression and rotating bending tests were performed on two steel alloys with different grades. Micro- inclusions presence and characteristics are quantified by a non- destructive SEM technique. The stress field around micro- inclusions is quantified by Eshelby’s model. A microstructural study is applied to relate failure and microinclusion parameters. This approach leads to the identification of a modified life model and stress intensity factor in the two loading cases.