Research Area

Magnetic & Optical Systems

Domain Visualization of Electrical Steel Sheets

The Domain Tester has been specially developed for the effective investigation of the domains of electrical steel sheets (SiFe alloys) under alternating field conditions. The grains of electrical steel sheets form different magnetic domains. Depending on their crystallographic orientation, different types of domains arise, which are characteristic for certain remagnetization losses.
With the Domain Tester, the domain structure can be observed and documented statically as well as dynamically (during the remagnetization). The following properties of electrical steel sheets can be investigated:

  • Domain structure,
  • Grain structure,
  • Grain sizes,
  • Crystallographic orientation of the grains in the plane,
  • Local defects,
  • Domain behavior during remagnetization

The big advantage is that time-consuming sample preparation is no longer necessary. The electrical steel sheets can be examined non-destructively without having to mechanically remove the insulation layer and polish the surface. Thus, in contrast to Kerr microscopy and MPI (magnetic particle inspection), a fast and high-resolution method is available for investigating the magnetic properties of electrical steel.

Active MO sensor surface: 18 x 13 mm
Resolution: 1 pixel = 14 µm
Image acquisition frequency during dynamic testing: 8 kHz
Video sequence (output): MP4 format, 30 s at 60 frames / s (slow motion)
Alternating field frequency: up to 400 Hz (yoke-supported), sinusoidal, triangular
Number of images per individual period: 160 images with AC field at 50 Hz
Manufacturer of the test specimen: thyssenkrupp

Timmy Reimann

Team Leader                                Crystalline Materials


Phone: +49 3641 282541