In order to investigate the effect of tensile prestrain on the corrosion fatigue strength, high cycle fatigue tests were performed on aluminium alloy (2017) sheet specimens prestrained by pulling under completely reversed plane bending stress in laboratory air and in salt water (3.0% NaCl). The conclusions obtained are summarized as follows;
(1) Corrosion fatigue strength for the prestrained specimens decreased in comparison with that for the as-received specimens, and it decreased monotonously with increasing prestrain regardless of the applied stress amplitude level.
(2) Cyclic work hardening and subsequent softening behaviours were observed repeatedly twice for the as-received and 3% prestrained specimens during the corrosion fatigue process. In the specimens prestrained above 3%, the saturation of work hardening took place at about 20% of the fatigue life and thereafter the work softening occured continuously until fracture under subsequent stress cycling.
(3) The number of cycles to crack initiation in corrosion fatigue decreased with increasing tensile prestrain. On the other hand, the number of cycles in the crack propagation period was independent of the tensile prestrain.
(4) It is suggested that the experimental results obtained in this test can be explained from a consideration that the barriers to the motion of dislocations are easily relaxed by the corrosive dissolution of the specimen surface prestrained during the stress cycling and the plastic deformation of grains easily occurs near the specimen surface.
