X-Ray Investigation on the Prediction of Fatigue Life : On the Changes in Half-Value Breadth of Age Hardenable Alloy under Constant and Varying Stress Amplitude

Abstract

As a continuation of previous investigation concern with prediction of fatigue life of steels under constant or varying stress amplitude, the fatigue process in age-hardenable Al-Cu alloy is studied by observing the half-value breadth of intensitity distribution curves taken from X-ray diffraction lines. It is found that the fatigue process of Al-Cu alloy is similar to that of annealed carbon steel from the stand point of the change of half-value breadth, namely, the relation between b/B and log n/N or log Σ n/N, where b and B are the current and the initial value of half-value breadth and n/N and Σ n/N are the cycle ratio or summation of cycle ratio respectively, is represented by a liner relation of magnitude or history of alternate stress amplitude. This relation offers a certain method of the prediction of fatigue life.