Analysis of forming capacity of HCT490X and DX57D depending on strain rate

Abstract

To evaluate the forming capacity in sheet metal forming, experimentally determined Forming Limit Curves (FLC) are often used. These curves represent the forming limits of a material. The most widely used approach to experimentally determine the onset of necking of sheet metals is formulated in EN ISO 12004-2. The first goal of this work is to investigate the limit strains for dual-phase steel HCT490X (commonly referred to as DP500) with a nominal thickness of 0.6 mm and deep drawing steel DX57D with a nominal thickness of 0.7 mm. The second goal is to evaluate the influence of punch speed (resulting in strain rate) on the position of forming limit curve for materials HCT490X and DX57D. The FLC curve is measured with the Nakajima test on a universal testing machine BUP 600. The test setup and the shape of the specimens follow EN ISO 12004-2. The stochastic, isotropic, and high contrast pattern was applied on the specimens and was measured using a 3D photogrammetric system ARAMIS by GOM. The punch movement velocity was gradually changed, and the experimentally measured results are compared with numerical simulation in AutoForm Forming R8.