Synergy effect of shear angle and anisotropic material ductility on hole-expansion ratio of high-strength steels

•The piercing punch with the dull rooftop improved the hole-expansion ratio.•The sharp rooftop deteriorated the hole-expansion ratios.•The hole-expansion ratio increased when the anisotropic material ductility redeemed the weakest point of the sheared surface.•Narrow clearances and high-tensile strength of the workpiece diminished the effects of rooftop piercing punch on the hole-expansion ratio.•Material anisotropic ductility was evaluated by the in-plane stretch bending test for the sheared edge.