Effects of Recently Developed Severe Shot Peening Treatment on Mechanical and Tribological Properties of AISI 304 Steel

This study investigates the effects of a newly developed gradient severe shot peening treatment (GSSP) on the mechanical properties and tribological behavior of AISI 304 steel. Some experimental tests, including microhardness and ball-on-disc wear tests, were conducted to evaluate the mechanical and tribological properties of both treated and untreated samples. The microstructure of the tested materials was analyzed using X-ray diffraction, optical microscopy, and scanning electron microscopy. Specimens treated with GSSP exhibited a reduction in mean crystallite size and an increase in hardness compared to specimens treated with conventional shot peening at a constant pressure. Samples treated by both conventional and gradient shot peening processes exhibited 50% to 75% of the wear experienced by non-treated steel specimens. An important finding of this study is that while the microhardness improvement in conventional shot pinning diminishes at a depth of 0.3 mm, it is sustained at depth of 0.4 mm and beyond in the GSSP. This study demonstrates the potential of the gradient severe shot peening technique to improve the mechanical properties of AISI 304 steel, primarily by reducing crystallite size and increasing hardness.