Simulation of Multi-step Tube Hot Gas Forming Process of a UHSS Torsion Beam

Abstract

AbstractUltra-high strength steel can significantly improve the safety and lightweight of vehicles, especially for the closed-profile components. In this study, a novel process simulation of multi-step tube hot metal gas forming (HMGF) of a V-shape torsion beam is conducted. The aim of this paper is to provide the insight into the influence of process variables, such as pre-heating condition, gas pressure and tool temperature, on the formability, hardening and component behavior. The press hardening steel used is hot-rolled BR1500 steel and the stress-strain relationships under different temperatures are investigated for the thermo-mechanical simulation. A consistent simulation model with all relevant sub-stages is then established in LS-DYNA software. Component geometry, wall thinning, hardness and microstructure distributions are achieved in the simulation and the forming parameter dependency is analyzed. And the forming equipment is introduced. The hot gas forming step is the most complicated process, and is carried out in a nitrogen gas environment, which prevents oxidation of the parts after heating.KeywordsUltra-high strength steelTube hot gas formingTorsion beamMulti-step forming