LAUSR

In thermal spray, grit blasting is the standard method used to prepare the substrate surface before coating deposition. This study examines the effect of the grit blasting parameters on the residual stresses, roughness and hardness of three metal alloys with widely different mechanical properties: low-carbon steel, Ti-6Al-4V and Inconel 718. It also estimates the density of dislocations using the Williamson–Hall method. The dislocation structures of low-carbon steel grit blasted at different grit impingement angles were observed under a transmission electron microscope. The surface dislocation density was found to increase with the blasting time and angle of impact. Moreover, the depth profile of the dislocation density was in good agreement with that of the hardness profile of the blasted specimen. The residual stress depth profiles of each material at different blasting pressure showed an increase in the value and depth of maximum compressive residual stresses. Both surface residual stresses and roughness were found to increase with the grit blasting pressure, angle and, to some extent, with time and stand-off distance. The mechanisms of material erosion were found to be microcutting and indentation at lower and higher angles of abrasive impingement, respectively. The extent of damage of the materials was explained on the basis of the Johnson–Cook flow strength model.