Effect of laser shock peening on austempered ductile iron

In this study, laser shock peening (LSP) has been applied on austempered ductile iron (ADI) to determine the optimum laser power and spot overlapping rate required for automotive gear applications. The surface roughness and phases present were studied to understand the effect of the laser shock wave application on the material. An increase in the mean surface roughness was achieved when the laser spot overlap increased from 20% to 60%. A significant increase in the microhardness was obtained in the surface and sub-surface, indicating an increased dislocation density of the material. Compressive residual stress depth and magnitude characterized by X-ray Diffraction (XRD) and Incremental Hole Drilling (IHD) were found to increase with laser power density. This work significantly identifies the pathway toward the engineering manufacture of austempered ductile iron and the application of LSP for the automotive drive-train industries.