The Relation between Fracture Ductility and Low Cycle Fatigue Life

A low cycle fatigue test and a microcrack propagation test were carried out under push-pull loading on low carbon steel and on pure iron, with special interest in the relation between the fracture ductility and the low cycle fatigue life. Results show that the low cycle fatigue life is not sensitive to the change in fracture ductility of the material for the ordinary low cycle regime in which the development of small surface cracks leads to the fracture of the specimen, and that this is closely related to the evidence showing that the rate of microcrack extension is not appreciably affected by the fracture ductility of the materials. Calculation of low cycle fatigue life on the basis of the law of small crack growth proposed in recent years revealed that only a small difference in fatigue life appears in the high and low ductility materials. Low Cycle Fatigue, Fatigue Life, Fracture Ductility, Manson-Coffin Law, Law of Small Crack Growth, Low Carbon Steel, Pure Iron.