Abstract
In order to examine the mechanism of so-called fish eye-pattern fatigue failure, usually being caused by initiation and growth of internal small crack, uniaxial push-pull fatigue tests were carried out on a high strength low alloy steel in vacuum, for modifying the environment during internal crack initiation and growth on specimen surface. The test results showed that the fatigue life was elongated and the crack growth rate was delayed in vacuum. Furthermore, the results of fractographic observation of crack initiation at inclusions revealed that the surface type crack initiation in vacuum resembles the internal fish eye-type crack initiation in atmosphere. Finally the fish eye-type fatigue life was well evaluated in terms of small crack growth law in vacuum.
