FATIGUE CRACK INITIATION AND CRYSTALLOGRAPHIC CRACK GROWTH IN AN AUSTENITIC STAINLESS STEEL

摘要

In the classical (crack growth) concepts used to predict the lifetime of specimens or components under cyclic loading, initiation and early growth are neglected. Instead, fictitious starter cracks are prescribed. Experiments with specimens made of the austenitic stainless steel with the german designation X6 CrNiNb 18-10 (approximately steel 316) showed that a significant part of the lifetime is spent for the initiation and crystallographic growth of microstructurally short cracks. In the present work the crack growth behaviour was studied with the classical fracture mechanics concept and with an effective crack length approach. Models for crack initiation and crack growth in the first grains of a polycrystalline aggregate are proposed.