Font Size: 

Even after consecutive decades of intensive activities, fatigue remains thesubject of great interest due to its critical role on structural integrity aspects regardless theapplication scale. As such, significant efforts have been continuously devoted to cycliclading on various scientific/engineering interfaces. The current study is centered on theultra long fatigue life regime which might stress the beneficial role of local vs. globalapproaches, particularly in terms of the fatigue threshold concept. Beside informationconcerning the mechanical response under cyclic loading up to the giga cycles regime inhigh strength Cr-Mo steel, fine scale features visualization and surface analysis weresupplemented. The study explores some of the basic elements in the sub critical micro crackstability behavior. In addition the inherent cyclic dependency of fatigue damage evolutionis emphasized. Experimentally based, relevant arguments emerged regarding the possiblerole of embrittling species in terms of mechanical/chemical interactions on the ultra longfatigue life behavior.