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New A8 Audi is again made of steel-The 19th China (Guangzhou ) Int¡¯l Casting product Exhibition
7/27/2017 casting expo-Die-casting expo-foundry expo |
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Steel is making a comeback: after experiments with aluminum in its luxury models, Audi reverts to steel on the new A8. In 2018, it is to be on the market: the body of the new A8 from Audi will consist of more than 40 percent of steel. This is in line with the trend among automotive manufacturers to use high-strength steels in new cars. It is a clear departure from the pure aluminum body, which Audi developed 1994 for the A8. Since then, steel has evolved enormously as a material. The tensile strength of steel has increased almost tenfold from 270 to 2,000 MPa over the last 20 years. More than 80 new steel products are currently being developed at ArcelorMittal. The steel offer for the automotive sector comprises almost 200 special steel grades, half of which have been marketed in the last ten years.
Approximately 17 percent of the body of the new A8 will consist of press hardened steel (PHS), some of which is supplied by ArcelorMittal. These steels have yield stresses of up to 1,500 MPa after press hardening. The weight-specific strength of these steels also surpasses that of the highly developed - and more expensive - aluminum grades.
Thanks to the development of new joining techniques, it is now easier than ever for automotive manufacturers to integrate high-strength steels into their vehicles. Since these technologies are now mature and are adopted by the automobile manufacturers, a strong increase in the use of PHS in vehicles with multi-material construction is to be expected. "Usibor® is our main product for hot forming and has been a major commercial and technical success in the automotive industry worldwide," said Brian Aranha, Vice President of ArcelorMittal Global Automotive. "The introduction of further improved products such as Usibor® 2000, which is 10-15 percent lighter than the previous hot-formed steels, will further increase the use of hot-formed products in vehicles." Usibor® is comparable to conventional press hardening techniques and processes. The combination of Usibor® and Ductibor® for laser-welded boards offers several clear advantages, for example weight savings, more favorable crash behavior and cost savings through material and production optimization.
Dr. Bernd Mlekusch, Head of the Lightweight Construction Center of Audi, explains: "There will be no cars built of aluminum in the future. Press-hardened steels (PHS) will play a special role in this development. PHS steels form the heart of the passenger compartment of a car and protect the occupants in an impact. Looking at the stiffness in relation to the weight, PHS is superior to aluminum today. "
The turnaround from Audi back to steel corresponds to an increasing trend, which, according to the figures of the Steel Market Development Institute (SMDI), also exceeds the expectations of steel producers. Between 2006 and 2015 the use of high-strength multi-phase steels in vehicles increased from an average of 36.7 kg per vehicle to 124 kg. This is a tripling in only ten years. More surprisingly, the use of high-strength steels increased by about 10 per cent annually from 2012 to 2015, significantly more than predicted by the steel producers.
-The 19th China (Guangzhou ) Int¡¯l Casting
product Exhibition
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