EFFECT OF SHOT PEENING ON RESIDUAL STRESS AND FATIGUE LIFE OF A SPRING STEEL

Abstract

Abstract This study describes shot peening effects such as shot hardness, shot size and shot projection pressure, on the residual stress distribution and fatigue life in reversed torsion of a 60SC7 spring steel. There appears to be a correlation between the fatigue strength and the area under the residual stress distribution curve. The biggest shot shows the best fatigue lie improvement. However, for a shorter time of shot peening, small hard shot showed the best performance. Moreover, the superficial residual stresses and the amount of work hardening (characterised by the width of the X‐ray diffraction line) do not remain stable during fatigue cycling. Indeed they decrease and their reduction rate is a function of the cyclic stress level and an inverse function of the depth of the plastically deformed surface layer.