Crack formation in blanking and piercing

In recent experiments on blanking and piercing, it was found that cracks occurred in the region of maximum hardness gradient and that cracking could be eliminated by radiusing the punch and die edges. In this paper, a simple stress analysis is made of the corresponding plane strain deformation, account being taken of the strain-hardening property of the work material. The above experimental observations are then shown to be compatible with the predicted stress distributions.