On the basis of fatigue data of specimen with surface defects

the size parameter of surface defects was proposed

and introduced into the Walker life equation to study the effect of size of surface defects. And the life prediction results of the equation were compared with the calculation results of life prediction method considering the stress gradient. The scatter bands of the results of two models were within ±3

indicating that the method is reliable. Then the equation was used in predicting the fatigue life of powder metallurgy turbine disk and obtaining the influence law of the surface defects with different sizes on the life of turbine disk. Its main engineering significance was that based on the stress characteristics of the dangerous position of turbine disk

the fatigue life with existence of the defect can be acquired. And even if the defects are not detected

it can ensure the safety in service period.