Hot-formed steels (here called 'Boron steels') offer a great weight saving potential versus conventional cold-formed steels used for crash relevant structural parts. Boron steels allow complex shaped parts due to the hot-forming process, which can be a direct or indirect process. In the direct hot forming process first the sheet metal with an initial yield strength of around sigma(indy) = 400 MPa is blanked and then heated in an oven up to some 950 deg C. In the next step the 'hot' sheet metal is stamped and at the same time rapidly cooled down (quench hardening process) in the stamping die. During this process the yield strength increases up to approximately sigma y > 1100 MPa in the final stamped part. Due to the enormous strength and the very good dimensional control (nearly no springback), more and more hot-formed parts are used in vehicle design. Especially in the body structure hot-formed steels are used for crash relevant parts. However the quench hardening process causes a significant reduction of the material ductility. The designer has to ensure via crash simulation that the crash impact can be handled without fracture of the Boron steel component. The prediction of the deformation and fracture behavior therefore is one of the major interests during the vehicle development process. The paper will give an overview on: material properties of Boron steels, a failure modeling approach for crash simulation, the validation of the failure modeling approach, application examples that demonstrate the lightweight potential of Boron steels for structural applications and the benefit of the chosen simulation approach.
Failure prediction of hot-formed steels in crash
Versagensbewertung von warmgeformten Bauteilen im Crash
2006
26 Seiten, 22 Bilder, 5 Quellen
Conference paper
English
Failure Prediction of Hot-Formed Steels in Crash
British Library Conference Proceedings | 2006
|Failure prediction of hot formed steels in crash
Automotive engineering | 2006
|Failure prediction of boron steels in crash
Automotive engineering | 2007
|Failure Prediction of Boron Steels in Crash
British Library Conference Proceedings | 2007
|Failure Prediction of Boron Steels in Crash
SAE Technical Papers | 2007
|