Department of Mechanical Engineering, Islamic Azad University, Doroud Branch, Iran
Department of Mechanical Engineering, University of Zanjan, Zanjan, Iran
In this study, the pitting type of corrosion growth characteristics, fatigue crack initiation and propagation behavior; axial fatigue tests were carried out on precipitation hardened martensitic Custom 450 steel in the air and 3.5wt% NaCl solution. Using the ratio of the depth to the half-width of the pits; (a/c)= 1.5±0.2 the corrosion pit depth growth law was obtained as a function of stress amplitude and elapsed time, t. Fatigue crack growth rates were determined in the near threshold stress intensity factors regime (∆kth). A model was presented for estimation of corrosion fatigue life based on the time to reach critical pit depth (as crack initiation) and crack propagation life. Then. S-N curves were obtained both in air and NaCl solution from axial fatigue testing. Comparison of data from the proposed model and the experimental results (S-N curves) showed good agreement.