Abstract
Eutectoid steels are used for variable kinds of industrial components. In addition, these components are usually pre-strained before use during production process or machining one. The object of this study is to evaluate the effect of pre-strain on the fatigue strength and to investigate the change of microscopic behavior. The main results obtained in this test are as follows (1) All of fatigue limits of different pre-strain ratio are lower than that of the original one. (2) Fatigue limit have no obvious change for different small pre-strain ratio. (3) Fatigue cracks initiate from slip lines or small cracks that are generated in the process of plastic strain.
