Some Factors Affecting the Fatigue Strength of Steel Members

DATA from several fatigue-test programs are examined in this paper for corroboration of basic factors which have been proposed for predicting more accurately the fatigue strength of full-scale steel members. Important among these factors are hardness, service loading, range of stress, and sharpness of the stress gradient at the critical zone.

Although the type of steel is often regarded as a primary factor, its hardness may be more basic, as it correlates better with endurance limit than other physical tests. Test results show that this hardness-strength relationship is useful in evaluating the effect of surface treatments on strength improvement in soft and medium-hardness steels.