In this study, high-tensile steel plates are pierced with a press working (PW) punch and a right-angle (RA) punch in incremental steps. The difference between the hole surfaces formed by these punches is observed to explain why the roughness of fracture surfaces of pierced holes varies with the type of punch used, despite the fact that punches do not come in contact with the fracture surfaces directly. The main results are as follows: (1) For the RA punch, a crack emanating from the corner of the punch and one emanating from the corner of the die meet each other. (2) The fracture surfaces of holes pierced with the RA punch show maximum roughness at the center, or at the junction of the two cracks. (3) The PW punch absorbs the stress at its corner, so cracks do not emanate from the punch side.
