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Residual formability of preformed and subsequently welded advanced high strength steels (Reform)

Final Report
Restumformbarkeit vorgeformter und anschließend geschweißter hochfester Mehrphasenstähle (Reform)
: Standfuß, Jens; Jahn, Axel; Weber, P.; Neges, J.; Wischmann, S.; Höfemann, M.; Sierlinger, R.; Cretteur, L.; Veldt, T. van der; Veit, R.; Trattnig, G.; Pickett, A.; D'Aiuto, F.

Fulltext (PDF; )

Luxembourg: Office for Official Publications of the EU, 2014, 142 pp.
ISBN: 978-92-79-38567-4
European Commission EC
FP7; RFSR-CT-2009-00016
Residual formability of preformed and subsequently welded adavnced high strength steels (Reform)
Report, Electronic Publication
Fraunhofer IWS ()
resistance of materials; Metalworking; steel; materials technology

The research project Reform was situated within the scope of research and technological development of steel and its utilisation. The central point of investigation was the determination of the load capability of preformed and subsequently welded parts made of high-strength steels. In order to cover a wide spectrum of automotive steel applications and with respect to the current development of modern high-strength steels, - two dual phase steels (HCT780X, HCT980X), - one trip steel (HCT690T), and - one complex phase steel (HDT780CD) were selected for the investigations at a sheet thickness of 1.5 mm. For comparison, the micro-alloyed steel HX340LAD acts as the low-strength reference and the press hardening steel 22MnB5 (quenched) represents the maximum hardening state. For the experimental verification of the material behaviour for different forming conditions, all selected materials (except 22MnB5) were preformed by stretching, biaxial stretching, deep drawing and rolling with two different strain levels each. The main result of the Reform project was to demonstrate the 'modus operandi in principle' for the assessment of the residual formability under crash loading conditions of subsequently welded high-strength steel components. Based on the experimental results, a closed loop simulation of the chain 'cold-forming - welding - crash load' for the prediction of the crash behaviour of car body components was evaluated at U-channel profiles as well as at crash bumper reinforcement demonstrator parts. Guidelines for the consideration of the influences of cold forming and subsequently welding on the behaviour under static, cyclic and crash loads are also given.