The effects of the ultrasonic impact treatment on the residual stress

impact toughness

and microhardness of 316L stainless steel was analyzed. By comparing the microstructure and fracture morphology of 316L stainless steel before and after UIT

the regularity of the mechanical properties by UIT is explored. The results indicate that after UIT

the surface residual tensile stress of 316L stainless steel is transformed into the residual compressive stress

with the average conversion rates of 204.97% in the x-axis direction and 198.74% in the y-axis direction

respectively. Additionally

the fibrous region increases

and the size and depth of the dimples become significantly larger

leading to the absorption of more energy in the Charpy impact fracture of 316L stainless steel

thus enhancing its impact toughness. UIT leads to severe plastic deformation on the surface of 316L stainless steel

thereby regulating the distribution of surface residual stress

refining the surface grains

and increasing the microhardness

thus comprehensively improving the impact toughness.