Evaluating the GMR-Limiting Dome Height Test as a new measure of press formability near plane strain

Abstract

A number of tests have been proposed as predictors of press shop formability. The most common of these are the Olsen cup, tensile, and hardness tests. However, none of these tests are very successful. Recently, A.K. Ghosh proposed the Limiting Dome Height test (LDH) to predict formability since this test modifies specimens to produce the same strain state at failure as found in a particular stamping. This report describes a correlation study in which specimens were collected from lots of steel and aluminum which exhibited either good or bad press performance in automotive stampings. The failure mode, in all cases, was splitting which initiated within ± 2 pct of plane strain. These specimens were evaluated by the LDH, Olsen, and tensile tests and compared to the actual press performance. Only the LDH test adequately separated the acceptable sheets from the bad.