Effect of Microstrains and Particle Size on the Fatigue Properties of Steel

Fatigue tests were run on notched SAE 86B45 specimens in bending at three hardness levels to determine the influence on fatigue of the X-ray measured parameters of microstrain and particle size. Changes in these quantities were produced by shot peening. The attendant macro residual stresses were shown to be equivalent to mechanically applied stresses and were compensated for by appropriate values of mean mechanical stress. Peening of the soft material produced large changes in microstrain and particle size and enhanced the fatigue limit. Peening did not alter the microstrain and particle size in the hard material.