Formability Evaluation and Strain Distribution at the Limit Dome Height Test of Dual-Phase Steel

The article deals with the formability testing of dual-phase steel DP800 that is used for the production of parts used in the rear deformation zone of the car body. The thickness of the steel was 1.6mm, and the Limit Dome Height test was performed on an Erichsen 145-60 testing machine. Specimens of different widths were stretched up to the fracture, and the punch path and force were measured. Specimens were etched to create a deformation grid of dots in order to measure the strain distribution using the photogrammetric system Argus. Then, the simulation model of the LDH test was created, and the punch path was set to calculate the strain distribution when constitutive equations Hill 48 and the Hollomon model described the material. The results of strain distribution measured experimentally were compared to those numerically simulated using both explicit and implicit simulation software. Limit Dome Height (LDH=23.5±1.5mm) was reached for specimen 108 mm, and measurements of strain distribution confirmed the plain strain state. A better description of principal strain distribution was reached at numerical simulation by the implicit simulation software, where the relative error of both the maximum stretching force and principal strains was lower.