Through the application of ultrasonic impact treatment technology to the surface of S355 steel

this research aimed to investigate the influence of different treatment durations on the material's microstructure

surface residual stresses

and tensile properties. The results show that ultrasonic impact treatment effectively mitigates residual tensile stresses in S355 steel while inducing compressive residual stresses. With an increase in ultrasonic impact treatment duration

the elimination of residual stresses along the

x

-axis and

y

-axis reaches values of 194.81 MPa and 200.46 MPa

respecti

vely

at a treatment duration of 10 minutes. Furthermore

ultrasonic impact treatment prominently elevates the material's tensile strength and yield strength. Specifically

at a treatment duration of 10 minutes

the tensile strength and yield strength experience increments of 16 MPa and 13 MPa. respectivelv. By ultrasonie impact treatment

refinement of grain structure on the sample's surface is observed alongside distinct manifestations of work hardening layers. A comprehensive analysis suggests that post ultrasonic impact treatment

the material's internal dislocation density increases

and grain refinement occurs

serving as pivotal factors in the release of residual tensile stresses and the enhancement of tensile performance. These outcomes provide an experimental foundation for a deeper comprehension of the mechanisms by which ultrasonic impact treatment contributes to the improvement of metallic material properties.