This paper was produced for the 2019 NAFEMS World Congress in Quebec Canada

Resource Abstract

Using high and ultra-high strength aluminium alloys to produce body panels and structural components is already gaining more popularity across automotive industry. The advantages of significant weight saving in comparison to steel, and efficient & cost-effective production in comparison to composites, while maintaining high structural and crash performance, are well proven. On the other hand, forming complex shaped components out of these alloys is very challenging - very limited formability, and serious springback issues, while trying cold forming processes and totally impractical cycle-time for large volume production while trying Superplastic Forming (SPF).



An innovative forming process - hot form quench technology, known as HFQ®, originally developed by Imperial College London (ICL), and since developed and commercialised by Impression Technologies Ltd (ITL), provides an ideal solution as it combines high formability with no springback, as well as a cycle-time that is measured in seconds not minutes, or hours, as in SPF. It consists of heating the blank sheet to its Solution Heat Treatment (SHT) temperature, to produce a homogeneous solid solution with high ductility, before it is moved to the press where the tool speed is set to a value that enhances the strain rate hardening of the material. The formed part is then held in the tool for a few seconds to quench to avoid the formation of precipitates in the microstructure and ensure high strength performance.



ESI Group has joined ICL and ITL, and several industrial and academic partners, in two separate EU collaborative R&D projects (LoCoLite and LoCoMaTech) to further develop its Sheet Metal Forming (SMF) software suite (PAM-STAMP) so it offers a comprehensive simulation-based solution for the design and manufacture of HFQ-parts. Utilising some of the existing capabilities in PAM-STAMP, and a dedicated viscoplastic damage constitutive model, ESI and partners were able to use the new tools to design and manufacture several automotive components using alloys from both Al-6XXX and Al-7XXX series.



The paper presents a brief introduction of the HFQ® process and the associated HFQ® Material Mechanical Model based on continuum damage mechanics model first, then an extended overview of the strategy adopted to incorporate the new constitutive model into PAM-STAMP as User Defined Material (UDM). Two industrial cases, selected out of an extensive and thorough validation programme carried out at ITL, are also discussed.