Fatigue Behavior of Nodular Cast Iron after Gas Nitriding

摘要

The paper presents and discusses the structural characterization, the fatigue behavior andrnthe fracture mechanisms of gas nitrided nodular cast irons (NCIs). Fatigue behavior is stronglyrndependent on structure but also on defects and inhomogeneity. Results of fatigue behavior onrnnitrided NCIs show a significant increase in fatigue limit and a different trend in the S/N curve inrndependence of type matrix. A link between microstructure and fracture mechanisms is found inrnfactors such as structure of NCIs, content of carbides, penetration depth and concentration ofrnnitrogen on the boundaries of ferritic grains below the white layer. The Murakami’s statisticalrnlargest size description of casting defects (pores) and inhomogeneities (nodules) is proposed andrnassessed using the present fatigue data.