THE CHANGING FACE OF DRIVE TECHNOLOGY – COLD ROLLED STEEL STRIP MATERIALS IN THE FUTURE

On November 19, 2020, Waelzholz gave a presentation on the relationship between automotive drive concepts and material requirements at the first digital edition of the 34^th  Aachen Steel Colloquium (Aachener Stahlkolloquium). This year’s online event was organized by RWTH Aachen University’s Steel Institute (IEHK). “Steel and more” was the theme of the event, which focused on materials technology topics such as developments and trends in materials for mobility concepts and additive manufacturing. New material design methods and concepts for damage-tolerant material use were also presented in a total of 25 video presentations by experts from the fields of industry, politics, and science.

As part of the “Materials for Mobility” lecture series, Norbert Brachthäuser, who is responsible for electrical steel strip materials technology at Waelzholz, among other areas, gave a presentation on drive concepts and the associated demand for cold rolled steel strip and electrical steel strip grades. Using various vehicle components as examples, Brachthäuser demonstrated that some materials are still needed for automotive manufacturing, regardless of the drive concept. This applies to the areas of safety, chassis, comfort, and seats. The traditional demand for low carbon steel strip for engines and drive trains, on the other hand, could be reduced or even eliminated in the future, for example in the production of valve cam followers. In contrast, hybrid systems and battery electric vehicles will lead to an enormous increase in demand for special materials such as electrical steel strip (figure 1).

Different electrical steel strip specifications are required depending on the electric motor concept, and their properties such as power dissipation, polarization, tensile strength, and workability must be carefully balanced. The strip thickness, for example, plays a crucial role in reducing eddy current losses. With its extremely low nominal thicknesses, Waelzholz’s non-grain-oriented electrical steel strip (NO grades) meets this requirement.

At the end of his presentation, Brachthäuser highlighted the company’s successful joint development work with RWTH Aachen University in the field of NO grades and presented the forecast volume requirements for this material (figure 2). “The increase in the number of units produced in the field of drive systems will lead to rapid growth in demand for these semi-finished products,” said the electrical steel strip expert.