When it comes to reconciling crash safety and lightweight design, steel remains the no. 1 material in the automotive industry. New manganese-boron steel alloys can achieve strengths of 1,500 MPa after hot stamping – far higher than with conventional forming processes. These high strengths have opened up whole new possibilities for lightweight automotive construction. Parts made from thinner material can deliver equivalent or even improved crash performance. Our latest innovation is ThyssenKrupp Hotform Blanks.
Audi is the first car manufacturer to use our new technology. The benefits are twofold: our tailored blanks can combine sheets of MBW® 1500 in different thicknesses. MBW® steel can of course also be combined with other steel grades, e.g. with lower-cost or milder materials. In addition, the blanks offer the advantages of hot forming. Very high strengths can be realized at very low weight.
For many years it was not possible to use tailored blanks in the hot forming process. This was because the coating on the MBW® 1500 material did not simply evaporate during laser welding. This resulted in uneven hardness during part forming.
Our solution is to remove the coating in the weld area. Thanks to our development work, this has been possible in production use since May 2007. Our Hüttenheim plant houses the world’s first laser decoating unit, producing 1.8 million tailored blanks per year for hot forming.
A concrete example of this is the B pillar: the vertical struts in the lower third have to yield so as to absorb some of the impact energy. The upper area of the pillar must be hard to protect the head and upper body of occupants in the event of a collision. Our solution is to weld the manganese-boron steel MBW® 1500 to milder steel grades and produce the complete B pillar from a hot-formed tailored blank. Strength after hot forming in the lower third is approx. 500 MPa. The residual elongation value is a good 15%. The sheet is just 1.5 mm thick in all areas – optimum material utilization while at the same time reducing weight. In addition, hot-formed parts are virtually free from residual stresses. That increases the value of your vehicle body.