From a new concept of urban electric micro-car to the development of new high-performance alloys, the Norwegian Group started off important initiatives to optimize the uses of light alloys in the automotive industry
by Alberto Pomari
Hydro is a name which stands out in the global aluminium system. Headquartered in Norway, Hydro is a fully integrated company with 35,000 employees in 40 countries on all continents, combining local expertise, worldwide reach and unmatched capabilities in R&D. In addition to producing primary aluminium, rolled and extruded products and recycling, Hydro also extracts bauxite, refines alumina and generates energy. The group operates in all market segments for aluminium and serves more than 30,000 customers.
For a long time Hydro has been strongly committed to the development of new solutions in aluminium for the global automotive industry both as regards materials and production technologies. We asked the managers of the different business areas involved to illustrate the latest initiatives carried out.
New micro-car concept putting aluminium in the middle of mobility for future cities
A joint study that Hydro has carried out with Forschungsgesellschaft Kraftfahrwesen mbH in Aachen (fka) and School of Design Pforzheim, related to aluminium use in urban vehicle concepts, clearly demonstrates aluminium’s strong position in vehicles of the future. The study was presented in September 2018 at Aachen Body Engineering Days 2018. Hydro participated with engineering expertise from three of its business areas: Extruded Solutions, Primary Metal and Rolled Products.
“This is a great example on how our customers and society can profit from Hydro being a completely integrated company with expertise along the whole value chain,” says Pascal Wagner, head of global products for Hydro’s Rolled Products business area. “This project has given us the ability to promote our broad product range to an important audience. Extrusion alloys, sheet grades and ‘green’ metals are all well appreciated,” says Wagner.
This past May, the United Nations’ Department of Economic and Social Affairs released a report stating that 68% of the world population would be living in urban areas by 2050. Further, the UN reported that sustainable urbanization would be key to sustainable development. With the macro-economic cost of traffic jams in Europe having tripled between 2006 and 2011, in addition to greater space limitations and carbon dioxide emissions in cities, conventional cars are being pushed out of cities. New vehicle and mobility concepts are moving in.
Focused on the L7e micro-car class, the new study by Hydro and fka demonstrates how cars for urban driving can be constructed largely in aluminium. It shows how aluminium can enable cars to achieve the L7e classification and still reach the safety levels typically provided by larger cars.
Light and agile micro-cars in aluminium
The L7e vehicle class describes a small and light, battery-driven micro-car. The requirements for such cars are:
• Under 3.7 meters in length, 2.5 meters wide,
and 1.5 meters high
• Lighter than 450 kilograms
(excluding the battery system)
• Maximum continuous rated power 15 kW
• Maximum speed of 90 kilometers per hour
• A closed body with no fewer than three opening sides
• Maximum of four non-straddle seats with safety belts
Cars within the L7e class, however, normally do not offer the same passive safety system for passengers as larger models. Consequently, customers have found such vehicles unattractive.
Raising the level of passive safety was one of the targets of the L7e project. “We tested the passive safety performance of our concept L7e micro-car according to Euro NCAP crash test methods – and the vehicle passed every test for normal M1-class cars,” says Nunzio Cuppoletta, automotive market director for Hydro’s business area Extruded Solutions.
Individual mobility in urban areas
Light and efficient micro-cars with electric drivetrains can contribute to ensure individual mobility in urban areas. The potential for aluminium lightweighting in these vehicles is substantial, due to the metal’s low density, good stiffness properties and high level of specific energy absorption.
The concept car’s innovative body structure was built exclusively with aluminium – structural sheet, extrusions and castings. All the extruded solutions were manufactured with 6xxx-series alloys, as well as all but one of the sheet components. “The main challenge with the body structure was to create a deformation space sufficient enough to guarantee the safety of passengers in case of a collision “ concludes Wagner. “Again, aluminium –with its high energy-absorption capability – was crucial for the new structure”.
New aluminium alloys for superplastic forming
Hydro is launching three new aluminium alloys specifically for hot-metal forming of aluminium sheet, mainly for complex automotive components. Each alloy offers properties that surpass the capabilities of the alternatives currently available in the global market. Automotive OEMs are interested in superplastic forming because the process enables aluminium manufacturers to produce thin-walled aluminium sheet components. It is a cost-effective process that can stretch the sheet at least 200 percent above its original size. Large parts can be formed out of one sheet and thereby replace more complex constructions consisting of a high number of small parts; other advantages include part consolidation and low forming stresses. Superplastic forming has been utilized for more than 25 years for specialty products by the aerospace segment, and the process is also being used to manufacture aluminium sheet components for buses.
The new element is therefore the broadening of uses in the automotive industry, as explained by Jonas Bjuhr, head of strategy, R&D and innovation for Hydro’s Rolled Products business area, and Rheinard Pritlaff, technical specialist for Hydro’s business area Rolled Products: “Automakers are developing increasingly advanced components, and this drives the use of superplastic forming, in this area we worked with some of them, as well as several tier suppliers, in developing three new alloys, they were two years in the making, and boast higher elongation or forming properties, achieve higher post- forming strength and enable lower cycle times than today’s alternatives. The three are new alloys are: next-generation 5083 alloy, new 5456 alloy and new 7020 alloy.
These are therefore alloys belonging to the Al-Mg family and to the heat treatment Al-Zn-Mg family, with quite different properties and possibilities of use.
In automotive the superplastic forming process offers carmakers the ability to lightweight their vehicles with aluminium rather than more exotic materials such as carbon fiber and composites, with our new alloys we can now offer the right material for components that the automakers need, Bentley as a significant example is using superplastic-formed aluminium sheet for the door/side panel of its new grand tourer, the Continental GT”.