Abstract:The fracture characteristics of high cycle fatigue slick samples of FGH 95 powder superalloy was observed, and the fracture feature law was put forward. The fatigue crack expanding peculiarity was analyzed using fractography quantitative analysis, and the fatigue expanding life was also calculated. On the basis of above research work, the internal relation between crack expanding peculiarity and fracture characteristics was analyzed. For 120 high cycle fatigue slick samples, the relation between fracture feature parameter ac and test fatigue life Nf was studied through statistical and inductive method. There is rough linear relation between logac and logNf, all of the data under the same temperature and stress ration R distribute among a disrupt strap with a certain width, and there are a top limit and below limit for the disrupt strap, the top limit line is approximately parallel to the below limit line. The critical crack length ac maybe used to evaluated the fatigue life using the top limit and below limit equations.