Experimental investigation of the strain rate dependence of SS2506 gear steel

摘要

Gears are commonly shot peened to increase their fatigue strength without adding weight. The correlation between shot peening parameters, target material and its fatigue behavior is still largely empirical. To further increase the knowledge of shot peening on gear steels and decrease costly experimental investigations this paper compared experimental single indents with carbide balls on Almen strip and gear steel test plates with FEM-simulations. The focus of the investigation was to find a strain rate dependence model including material parameter values that could predict the indent depth at velocities commonly used in shot peening. This was successful for an Almen strip steel (SAE1070) which could be modelled using a Johnson-Cook strain rate model with parameter C=0.035. For the gear steel of type SS2506 (EN 20NiCrMo2-2) the behavior was not entirely captured with any strain rate model. A possible explanation for this was the transformation of retained austenite that was present in the gear steel.