There are many situations where structural components are subjected to combined impact and fatigue loading such as railway shaft, any rotator shaft which subjected to shock loade, wheel shaft of airplane on the landing and …, It is evident that for the same fatigue load, the corresponding fatigue life of metallic materials will be different with and without the presence of impact loads. This paper presents the results of an experimental investigation carried out using a steel forged material, EA4T, to firstly explore the interaction of impact and fatigue loading conditions, and secondly to examine then influence of the sequence of impact /fatigue loading steps (i.e. reversing the order of loading steps without changing the load magnitude) on the fatigue behaviour of the steel. Finally, the experimental results of Charpy test and fatigue test according to ASTM E23 and ASTM E399-08 are compared with the results of finite element analysis of the combined impact /fatigue loading of the test sample.

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