There are many situations where structural components are subjected to combined impact and fatigue loading. It is evident that the impact strength of metallic materials changes following a history of fatigue loads. Similarly, the fatigue behaviour of metallic materials (fatigue strength and fatigue life) changes after the application of impact loads, i.e. for the same fatigue load, the corresponding fatigue life of metallic materials will be different with and without the presence of impact loads. Predicting the fatigue life of metallic materials, when, they have been subjected to a history of impact loading, is very complicated. This is mainly due to the complexity of the mathematical analysis for the transient stress history and the effect of stress waves reflected on the specimen boundaries. 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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