ABSTRACT
The early stage of fatigue crack propagation, where fatigue cracks initiate at defects and propagate to various crack geometries, can be evaluated by using L E F M models and F C P R data acquired under Kmax constant testing condition. Depending on the physical appearance of the initial defect (a single loose grain, a series of loose grains, inclusions, single and multiple initiation sites etc.), the fatigue crack growth has to be studied in at least two to three phases. This is necessary to apply appropriate L E F M models individually during a specific phase. As the evaluation demonstrates, most fatigue life is consumed in the first phase.
