Evaluation of Corrosion Fatigue Crack Initiation Life of 13Cr Steel
In this research, corrosion fatigue crack initiation tests using 13 Cr stainless steel were conducted in synthetic seawater to investigate the corrosion fatigue crack initiation life (Nc). In addition, a corrosion fatigue crack initiation and propagation model was suggested also. Until now, corrosion fatigue crack initiation life was treated ambiguously. The important point of this model is the suggestion of the moment of the corrosion fatigue crack initiation life at which the critical size of the corrosion pit changes to the crack. As the crack which emanates from the pit is usually small, accordingly it is treated as a small crack. In addition, the observation of the corrosion fatigue fracture surfaces using SEM were conducted. And the fracture mechanics analysis using an intrinsic crack model was conducted for the treatment of the small crack. Finally, the following were obtained. In the case without a clear stress concentration point which seems to fall into a corrosion fatigue crack initiation, as the meaning to define the number of cycles, at which the fatigue crack propagation rate becomes faster than the corrosion pit growth rate so that the fatigue crack initiates from the pit and its propagation starts in earnest, as the reasonable and universal corrosion fatigue crack initiation life (Nc) has been clarified.
Soon-Bok Lee and Yun-Jae Kim
W. B. Kim et al., "Evaluation of Corrosion Fatigue Crack Initiation Life of 13Cr Steel", Key Engineering Materials, Vols. 326-328, pp. 1007-1010, 2006