2. electrical steel (lamination steel, silicon electrical steel,
silicon steel, relay steel, transformer steel) is an iron alloy
tailored to produce specific magnetic properties: small
hysteresis area resulting in low power loss per cycle, low
core loss, and high permeability.
Silicon (Si) steels are alloys of Fe and Si having important
electrical applications (motors, transformers,
etc.). Nonoriented (NO) steels and grain-oriented (GO) Si
steels are referred to as electrical steels. NO Si steels have
applications in rotating machinery; GO Si steels are used in
devices (e.g., transformers) where an EMD parallel to a roll
direction is desired. GO Si steels are further subdivided
into regular grain-oriented (RGO) and high-permeability grain-
oriented (HGO) materials
Silicon transformer steels have traditionally been limited to
compositions of 3.5% Si or less, because significantly higher
silicon contents tend to lead to ordering and loss of ductility.
However, it has long been realized that increased silicon
concentrations would be desirable because of increased
resistivity (and resulting decrease in losses) and decreased
magnetostriction.
The conventional process for manufacturing regular grain-
oriented material involves hot-rolling a cast ingot near 1370°C
to a thickness of about 2 mm, annealing at 800–1000°C, and
then cold-rolling to a final thickness of 0.27–0.35 mm in two
steps, with a recrystallization anneal (800–1000°C) in-between.
The final cold reduction is about 50%.
3. For transformer applications,FLUX LIES PREDOMINENTLY along
the length of the laminations and therefore desirable to
enhance permeability in this direction.This is achieved by
various hot and cold rolling stages to produce textured
sheets,known as grain oriented silicon steel with the {001}
direction along th length of lamination.
Iron Silicon Alloys are used for transformer cores. In the
electrical power industry, volrage is always AC and of low
frequency 50-60 Hz. At these frequencies currents are
generated in transformer cores,alloying iron with silicon has
large effect on elelctrical resistivity with an increase of 4 for
every 3% si.
Silicon also has benefit of reducing magneto-
striction(length change during magnetization),and magneto-
crystalline aniosotropy.
