Traffic on Germany's roads causes around 160 million tons of CO2 every year and is thus responsible for around 20 % of the country's total CO2 emissions. An extremely effective measure to reduce CO2 emissions caused by automobiles is to reduce their weight through functional lightweight design. To reduce chassis weight economically and ecologically without compromising occupant safety, three different technologies or measures are currently being used. These are firstly the increased use of ultra-high-strength aluminum alloys, secondly the aluminum-steel composite design, and thirdly stress-optimized tailor welded blanks (TWB) made from steel sheets with different strengths and thicknesses.
The automotive industry is striving to combine these measures in the form of high-strength aluminum-TWB and hybrid aluminum-steel-TWB in order to be able to further reduce vehicle weight. To this end, novel welding configurations and heat treatment methods were developed at the University of Stuttgart, which for the first time enabled the economical joining of high-strength aluminum-steel joints with sheets of different thickness. The friction stir welding (FSW) process used in this process is subject to high demands on the process parameters, which is further complicated by large tolerance fields of the blanks used.
This project involves the development of new machine concepts for the production of large-format TWBs and quasi-continuous Tailor Welded Coils (TWC) in mixed aluminum-steel construction. In both cases, control and monitoring concepts are being investigated which should enable the new machine design and robust process control to be taken into account in order to ensure sufficient process reliability and thus quality of the TWBs despite the challenges described. The overall aim of this project is to further develop solutions previously researched on a laboratory scale and to increase the degree of maturity of the entire supply chain by transferring technology from research institutions to industrial manufacturers. With the widespread introduction of this technology, it is hoped that the CO2 emissions of automobiles can be reduced by up to 15% through functional lightweight construction.