Electrical steel from voestalpine creates mobility

Modern electromobility requires highly effective electrical steel. Do you know what makes this steel strip so special? And did you know that voestalpine is one of the top European suppliers in this sector with isovac®?

Electromobility requires two output components on the drive side: batteries—and electric motors with electrical steel strip. These thin steel strips form the heart of the motors and largely determine their efficiency. With its isovac® and backlack-v® products, voestalpine is one of the top suppliers in this core area of electromobility.

High demand for electrical steel

Electrical steel has never before set so much in motion as it does today, and never before has so much of it been needed. Depending on the size and type of drive motor (battery-powered or hybrid vehicle), between 10 and 100 kg of electrical steel are used to produce it, including the residues from stamping. Considering that electric vehicles sales could reach 14 million by 2025, as concluded by “The role of steel in electromobility” study by Handelsblatt Research Institute on behalf of voestalpine (HRI study), it is easy to imagine the demand scenarios. Industry experts expect a five-fold increase in the demand for electrical steel used to power electric cars over the next five years. By 2040, this should increase to 20-fold.

What makes electrical steel so special?

Looking at it, there is nothing spectacular about electrical steel strip—it is flat rolled steel that is stacked to form laminated electrical steel packages to ensure efficient operation of the electric motor. It is the physical properties of this soft magnetic material that make it special. Such materials are especially easy to magnetize (experts speak of high permeability). Simply put, they can amplify magnetic fields.

Another special property of electrical steel is its high specific electrical resistance. The significance of this property is seen in the functioning of the electric motor. When the polarity of the magnetic field between its stator and rotor is constantly changed, not all the transmitted energy is converted into motion. Part of the energy is lost as heat, the remagnetization (heat) loss. Electromobility has special requirements in this regard. In a household vacuum cleaner, for example, the polarity changes 50 times a second (50 Hertz). In an electric car, it changes at least 400 times a second. In order to reduce the associated heat loss, electrical steel is alloyed with silicon, which increases its electrical resistance.

But caution is required. Too much silicon lowers the cold formability of electrical steel. The skill of manufacturers lies both in selecting the appropriate amount of the alloying agent and in special production technology.

Backlack finishing

The surface of electrical steel is also very special. Individual layers are stacked to produce packages and must be electrically isolated from each other. After the last metallurgical treatment, the strip is coated with a micrometer thin layer of varnish.

In order to manufacture electrical steel packages efficiently, this layer can consist of a backlack that insulates and, after being heated for a short time, fully joins the individual lamination stacks over the entire surface. This eliminates the need for mechanical joining and welding, which can adversely affect the magnetic properties.

With backlack-v®, voestalpine Stahl GmbH has developed a unique product. As Christian Schreiner points out: “isovac® electrical steel coated with our backlack-v® provides great advantages for series production of electric cars. It quickly and cleanly joins the individual laminations and requires a lower temperature and less pressure for curing, effectively shortening production cycles.

More information: http://www.voestalpine.com/isovac

A myriad of electrical steel applications in electric vehicles

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