Corrosion fatigue crack growth rate (CFCGR) of Mn-Ni-Cr steel at low cyclic frequencies is estimated via a novel method called frequency shedding method. The results show that the CFCGR increases an order of magnitude with decreasing frequency, from 5 Hz to 0.01 Hz, at a given constant stress intensity factor. Application of a cathodic potential (-900 mV SCE) reduces the CFCGR close to fatigue crack growth rate in lab air over the frequency range (5-0.1 Hz). Results of an one dimensional model of mass transport of corrosion species (Fe2+, FeOH+, Na+, Cl-, H+, OH- ions) within a crack present in a steel specimen under NaCl solution simulated using time dependent Nernst-Planck equation is presented. © 2017 Chinese Society of Theoretical and Applied Mechanics. All Rights Reserved.