Fatigue life estimation of pre-corroded 42CrMo4 subjected to accelerated pitting corrosion method

Abstract

One of the main causes of failure of the components and structures used by Oil&Gas and offshore industries is associated with pitting corrosion. In this work, two main objectives have been defined. Firstly, the main variables to perform accelerated pitting corrosion on 42CrMo4 steel under laboratory conditions are defined. These accelerated corrosion tests have been performed to obtain pitting defects as similar as possible to the real ones observed in offshore environments. Secondly, fracture mechanics has been applied to predict the fatigue propagation of pitting defects until the final fracture, and a sensitivity analysis has been performed to determine the influence of geometric parameters on the fatigue failure predictions. Finally, a series of fatigue tests were carried out to obtain the S-N curves of the pre-corroded steel specimens and the results have been compared with the fatigue predictions. The main conclusion of the paper is that fracture mechanic approaches can be used to predict the fatigue life of 42CrMo4 subjected to corrosive environments in a reasonably conservative way.