Bendability evaluation of sheet metals in three-point bending test by using acoustic emission features

In this work, bendability evaluation of three sheet metals, a galvanized steel (JAC780Y), a stainless steel (SUS304) and a cold rolled steel (SPCC) was precisely investigated using an acoustic emission (AE) technique. A three-point bending test, with three different punch plate radii, was performed to evaluate the formability of the metal sheets in bending and hemming processes. Bending force–displacement curves were derived from the results of the tests and were correlated with AE features (Root Mean Square and Peak-to-Peak) that were extracted from data obtained during those tests. These correlations showed for the first time that AE techniques could be used to detect an intercrystalline fracture from bending behavior and also to evaluate the bendability of the given materials.