Assessment of Deep-Drawability and Stretchability by Bulge Test of Concentrically Grooved Metal Disks

In order to obtain new parameters available for assessing deep-drawability and pure-stretchability of sheet metals, a bulge test employing concentrically grooved disks is investigated. Both the limiting polar height and the thickness strain measured at a designated point near the groove in a burst specimen are useful for the assessment of pure-stretchability. Moreover, the foregoing two formabilities can be assessed relatively well in terms of the oil pressure and the geometry of specimens at burst initiation. These three parameters can be obtained by a single-blank test.