Diamond pressing versus shot peening

Shot peening and diamond pressing are cold working processes available for modifying surface properties of metals, thus, making a comparison between them in terms of improvement the surface integrity is especially crucial. This paper reports the results of experimental study of different pressing and peening variables on surface roughness, microhardness, and microstructure of heat treated alloy steel (D2): namely, pressing force and feed rate, and shot peening air pressure, stand-off distance, and exposure time. The results showed that diamond pressing could increase the surface hardness under the selected specified conditions by 62%, whereas a slight improvement, when compared with diamond pressing, could be achieved by shot peening (about 70%). Contrary to shot peening, diamond pressing significantly improves the smoothness of the steel surfaces. Average peening treatment was result in roughness of 2.2 μm to 3.6 μm, whereas the obtained by diamond pressing average roughness was ranged from 0.1 μm to 0.26 μm.