Abstract: A contrast test investigation on the combined fatigue lives of slightly and heavily corroded turbine disc slots has been carried out at high temperature under two vibration frequencies 50 Hz and 100 Hz.In order to estimate the service life from the test life,a new two-frequency-ratio method is proposed to convert the tested combined fatigue loads and life into service ones in the field.The conversion results can be taken as criteria for discarding the corroded turbine disc.