Abstract
In order to clarify the impact fatigue characteristics of ADI, impact and conventional fatigue tests were carried out in high cycle region mainly. SEM observation and measuring of retained austenite content using X-ray diffraction method were conducted on fracture surfaces of test specimens. In S-Nf diagram, life of impact fatigue was smaller than that of conventional fatigue, and there was more difference between both tests with lowering maximum stress. It was seen that macroscopical and microscopical roughness of fracture surface in the impact fatigue test were larger than that in the conventional fatigue test. Change of retained austenite content and its variation in the depth direction on fracture surfaces in the impact fatigue test were greater than those in the conventional fatigue test.
