Prediction of the growth of fatigue cracks taking environmental factors into account

Abstract A model of corrosion fatigue is proposed which takes into account the main phenomena of a mechanical nature, namely, the transfer of the active agent from the month of the crack to its tip, the accumulation of mechanical damage due to cyclic loads and the breakdown of the stability conditions in the body-with-cracks — load — environment system as the reason for the propagation of the crack tip. Particular attention is devoted to the mechanism by which active agent is transferred. In addition to diffusion, convective transfer as a consequence of the change in the shape and dimensions of the crack cavity is taken into account. The results of modelling are supplemented with diagrams, which relate the rate of growth of the crack with the range of the stress intensity factor, the concentration of the agent at the mouth of the crack and the characteristics of the cycle, equal to the ratio of the extremal values of the applied stresses in each cycle. The results are compared with experimental data.