Trending Topics in Edge Ductility Research

Advanced High Strength Steels (AHSS) often exhibit issues in so-called edge ductility. The residual deformation available in a cut edge is limited by the cutting operation. And although better edge preparation methods are available they are not economically viable and hence shearing/cutting remains the preferred option. After years of research many influences on cut edge formability are known. For instance that the optimal clearance in AHSS is larger than that prescribed in the ISO TS16630 test standard. That sharp tools make a difference. It is also still seen that the test shows considerable scatter and difference between labs. 

But there are also a number of lesser known phenomena. The delay time between cutting and forming sometimes makes a difference. The speed of cutting can make a difference. A second cut of only a fraction of material (so-called shaving) can make a significant difference but the difference depends strongly on sharpness of tools. The gradient of strain in radial direction is thought to have an influence on the results. Alternative tests to HEC may yield different ranking of materials. Links are being found between fracture toughness and HEC, and between local ductility and HEC. These links, however, do not necessarily apply to all materials. 

This paper aims to give an overview of the newer findings from projects that the author is involved in as well as recent literature that has come to the attention of the author.