THE EFFECT OF REST PERIODS ON THE FATIGUE STRENGTH OF Ti‐6A1‐4V

Abstract The monitoring of fatigue crack initiation mechanisms and short fatigue crack growth usually involves interrupting otherwise continuous load cycling for examination of the test‐piece. This permits attainment of high resolution over a large area of surface where the fatigue cracks could initiate. However, breaks in the fatigue cycling can affect the fatigue endurance of the test‐piece and in the present study of Ti‐6A1‐4V this has been shown to depend on the duration of the rests, the number of cycles between rests, the type of examination employed and the hydrogen content of the material. The results of the work are discussed in terms of the possible influence of the monitoring technique on the fatigue process.