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A large set of bending fatigue data on carburized steels has been statistically analyzed to quantitatively describe the effects of process and microstructural variables. Increasing demands on gear steels require a broad examination of past bending fatigue research to reveal the primary factors that determine fatigue performance and guide future gear steel design. Fatigue performance was correlated to specimen characteristics such as retained austenite content, case and core grain size, extent of intergranular oxidation, surface roughness, and the case profiles of residual stress, hardness, and carbon content. Prior austenite grain size in the case and surface residual stress were found to most strongly influence bending fatigue endurance limit. A multiple regression model to predict endurance limit achieved an R-squared value of 0.56.

The quasi-static denting behavior of sheet steels has been analyzed in a systematic FEA study, which considers material properties, panel radius, sheet thickness, panel length and boundary conditions. Results from a full factorial experimental matrix have been analyzed statistically to identify those variables and variable interactions that influence dent performance. The primary factors which control dent performance are material properties, panel radius and sheet thickness, while panel length and boundary conditions are not significant. Based on the results of this study, two commonly used dent criteria (loading energy and visible dent load) are analyzed, and previously reported opposite effects of radius of curvature on dent performance are clarified.