EFFECT OF COMPRESSION PRECRACKING ON THE NEAR THRESHOLD FATIGUE CRACK PROPAGATION IN AN AISI 316L STAINLESS STEEL

This work describes an alternative test procedure based on fatigue precracking under compression to mitigate the potential effects of crack closure on near-threshold fatigue data and, thus, to obtain more consistent and reliable.Kth-values. The method relies on performing a compression precracking, in which both maximum and minimum loads are compressive, thereby resulting in a tensile residual stress field at the crack tip. Fatigue crack growth (FCG) tests conducted on an AISI 316L stainless steel provide the experimental data upon which the near-threshold fatigue crack growth rate data for different test techniques can be determined. Overall, the present investigation shows that combining the compression precracking technique with the utilization of non-standard bend specimens having increased span improves evaluation of the near-threshold fatigue crack growth rate data for the tested AISI 316L steel, thereby providing more accurate Delta K-th-values.