The fatigue life of flawed materials such as cruciform joints with lack of penetration (LOP) defects may be separated into two portions: that fraction of the life in which flaws sharpen to become active fatigue cracks (initiation), and that fraction in which the sharpened cracks steadily enlarge until fracture occurs (propagation). A two-stage propagation model for life prediction based on fracture mechanics approach incorporating near-threshold crack growth data has been offered. The experimental part consists of fatigue tests for cruciform joints of AISI 304L stainless steel. Constant amplitude fatigue tests with stress ratio, R = 0 have been carried out with a frequency of 30 Hz. This study suggests that the life prediction using the proposed two-stage propagation model was simple, accurate and requires limited and known parameters.