Build-up line, side trimming The starting material for our grain oriented electrical steel is hot rolled strip, which is produced by ThyssenKrupp Steel AG according to precisely determined specifications.
Hot annealing and pickling line The hot rolled strip intended for PowerCore® H is annealed and shot blasted before pickling to achieve optimal conditions for the formation of the required texture.
Cold rolling After this the strip is cold rolled using special cold rolling mills. PowerCore® H undergoes the cold rolling process to nominal thickness in one step.
Decarburization In the following decarburizing annealing line the carbon content of the strip is reduced to a level which avoids magnetic ageing. Simultaneously, a thin oxide layer on the strip surface is formed. After decarburizing, the surface of the strip is coated with an annealing separator (magnesium oxide) to prevent the sticking of the windings of the coiled strip in the subsequent high temperature annealing.
High temperature annealing During the high temperature box annealing under protective atmosphere, the texture is developed by selective grain growth. Then, by reaction of the annealing separator with the oxide layer of the strip, a forsterite layer, the so called glass film, is formed. Additionally the material is refined by diffusion.
Stress relief annealing and coating In the next step the grain oriented electrical steel strip is insulation coated, thermally flattened and undergoes stress relief annealing.
Laser treatment An irradiation by laser beam, perpendicular to the rolling direction, reduces the size of the magnetic domains of thin PowerCore® H, leading to a reduction of the total core loss. As this further core loss improvement is not thermostable, laser scratched material should not undergo further stress relief annealing.
Slitting, side trimming By side trimming and slitting, the grain oriented electrical steel strip is finally cut to the widths ordered by our customers.