The Effect of Surface Micropits upon the Fatigue Strength of High-Strength Steel

A study has been made of the influence of artificial semispherical surface flaws with diameters of 25 to 175 μm upon the fatigue limit of high-strength steel. This has been done to better understand the origin of the harmful effect of hard inclusions on the fatigue resistance of high-strength steel in which hard inclusions are poorly bonded to the matrix microstructure. An attempt has been made to estimate the true fatigue limit of the ideal inclusion-free microstructure of the steel, and the effect of inclusions on the fatigue strength of the steel has also been discussed quantitatively on the basis of the results of such an estimation of the true fatigue limit.