Abstract: In the present study,experimental investigations are carried out or the effects of the waveforms( including triangular, postitive sawtooth,negative sawtooth.scuare and negative pulse) and the frequencies (including 1, 5, 20Hz) of cyclic loading on the fatigue crack propaga-tion(FCP) for GC-4(40CrMnSiMoVA) steel.in the neutral solution of 3.5% NaCl.Test results show that the wavefrom and frequency have great effect on FCP rates of GC-4 steel in 3.5% NaCl solution.Moreover,the analysis of experimental results also show that the static stress corrosion cracking(SSCC) and the dynamic stress corrosion cracking(DSCC) can occur simultaneously in the corrosion fatigue(CF) process and that the DSCC may occur when Kmax

Key words: corrosion fatigue, stress corrosion cracking, crack propagation, waveform, fre-quency