Understanding and Development of Pseudo Glass Film for Grain Oriented Electrical Steel
Ashley Spencer Hill1, Dr Justin Searle1 , Dr Paul Bingham3 , Dr Fiona Robinson2
College of Engineering1 , Swansea University, Swansea, Orb Electrical steel2, Cogent Power Ltd, Tata Steel, Newport, Sheffield Hallam University3
Grain Oriented Electrical Steel (GOES) is a specialist steel which are processed to thin laminations (0.23 – 0.35mm) to form a core in a transformer. These transformers are used to
upscale and down scale the alternating current to provide the necessary voltage to customers.
During the grain oriented electrical steel production process a critical stage is the formation of a thin (1 – 2 microns) Forsterite (Mg2
), “glass film” layer on both surfaces of the
steel. The “glass film” is required to provide surface insulation in addition to introducing a tension in the steel as a result of the difference in the coefficients of thermal expansion
in steel and “glass film”
Selected samples of grain oriented electrical steel (3.0 – 3.2 wt.% Si) of final thickness 0.23mm with minor alterations to production conditions have been examined in order to establish
the key parameters affecting the development of the Forsterite layer. Techniques including AFM, SEM, XRD and GDOES have been employed to investigate the influence of surface roughness,
oxides and production parameters on the formation of Forsterite.