Abstract
Fatigue strength of high-strength sheet steel is deteriorated by piercing, and coining to the pierced hole improves the fatigue strength, which makes an edge of hole smooth and introduces compressive residual stress at the edge of hole. In this report, using FEM analysis, the behavior of material at the edge of hole during coining is investigated. As a result, radial deformation of the hole has a large effect on the behavior of residual stress after coining and improvement of fatigue strength can be explained by this compressive residual stress.
