Numerical comparison of advanced high strength steels forming limit curve using Banabic and Nakazima tests

With the increase of government regulation, pressure to reduce environmental impact, fuel consumption, and safety improvements, the steelmaking industry has developed Advanced High-Strength Steels. However, the application of these steels depends on the knowledge of mechanical properties and parameters of the forming processes. Forming limit curve (FLC) is an important tool used to evaluate the formability of sheet metal. The aim of this study is to modify and analyze the Banabic method to the standards of DIN EN ISO 12004-2 and then comparing it to the Nakazima test using first generation Dual-phase 600. For this purpose, numerical simulations with experimental data verification, the differences of both methods were performed. Based on finite element simulations the adapted Banabic method resulted in uniform punch force and strain profile than Nakazima specimens. The Banabic test method provides greater strain, stress distribution and maximum strain values ​​closer to the punch pole in their specimens. Therefore, modified Banabic method has advantages over the Nakazima test, as to induce a fracture behavior closer to the punch pole in the same friction conditions and easier machining of specimens.