Influence of surface topography and needle size on surface quality of steel plates treated by ultrasonic peening

• Fold defects were a key factor determining surface quality and fatigue life.
• Widths of surface topography and indentations were critical to fold defect formation.
• The depth of surface morphology D determines the dimension of fold defects.

Five groups of D36 steel plates with different surface topographies were prepared to evaluate the influence of topography and needle size on the surface quality after ultrasonic peening treatment. Factors such as the stress distribution, micro-hardness, and fold defects were studied to quantify the surface quality. In addition, ABAQUS/Explicit finite element modeling was employed to simulate the peening process. The numerical results revealed that fold overlapping was dependent on the initial surface topography and the size of the peening needle could influence the morphology of the fold defects. The results further indicated that fold defects were closely related to the initial surface topography, with the aspect ratio being a key determining factor for the dimensions of fold defects.