Predicting Formability of Sheared Holes in a Variety of Sheet Steels

摘要

In 1986, Adamczyk and Michal developed an equation for predicting the deformation limits during hole-expansion for finished holes in HSLA steels. These researchers found that the r-value plays an important role in determining the limits of this type of deformation in sheet steel. As the tensile strength increases into the range of current advanced high strength steels, formability of the sheared edge can decrease dramatically. Elongated inclusions can also cause the toughness of sheared edges to be orientation dependent, and limit formability. The current work investigates the impact of steel mechanical properties and sulfur content on the formability of sheared holes for a wide variety of sheet steels. These include interstitial free, bake hard, HSLA, structural, dual phase, ferritic stainless and austenitic stainless. Special attention is paid to the dual phase steels. The predictive equations developed will aid the initial material selection process for parts containing expanded or extruded holes.