Electrical steel, also called silicon steel, is the core material of every transformer, motor and generator, and its losses translate directly into efficiency. The two families, grain oriented and non oriented, serve different jobs, and within each family the grade, thickness and coating decide the loss figure. This guide covers the grade systems, the specification axes and the sourcing checks.
The two families and where each belongs
Grain oriented, for transformers
Grain oriented silicon steel, designated with grades such as 23QG085, 27QG100, 30QG110 and the thin 0.18 mm high permeability grades, has a crystal structure oriented to align with the rolling direction so that losses are very low along that direction. It is used in transformer cores, where the flux path is aligned with the rolling direction, and it is normally specified by the core loss at a defined induction and frequency, for example loss at 1.7 tesla and 50 hertz. Higher grades, and thinner gauges, give lower loss and are chosen where efficiency or size is critical.
Non oriented, for motors and generators
Non oriented silicon steel, grades such as 35WW440, 50W800, 50W600, 35W270, 35W300 and 30SW1700, has more uniform magnetic properties in all directions, which suits rotating machines where the flux path changes direction. It is specified by core loss and by magnetic induction at a defined field strength, and the choice balances loss against the mechanical and cost requirements. New energy vehicle traction motors use thin, high strength, low loss grades to cut losses at high speed.
Electrical pure iron
Electrical pure iron, such as DT4, is a very low carbon iron with high permeability and low coercivity, used for relays, magnetic shielding, pole pieces and electromagnetic components where high permeability at low field matters more than loss at high frequency.
Specification axes that decide performance
Core loss at a defined condition
Core loss, or specific total loss, is the headline figure and must be quoted at a defined induction and frequency, and at a defined thickness. A loss figure without the condition is meaningless. Both the hysteresis and the eddy current component matter, and the balance between them changes with thickness and with frequency.
Magnetic induction
Magnetic induction at a defined field strength tells you how much flux the material will carry for a given excitation, and it drives the size of the core. High permeability grades are specified for transformers where size and no load loss matter.
Thickness and thickness tolerance
Thickness drives eddy current loss and stacking factor. Thin material cuts loss at high frequency and is used in high speed motors and high frequency transformers. Thickness tolerance and thickness uniformity matter because they affect the stacking factor and the local flux distribution.
Coating type
The insulating coating must be specified: an inorganic coating for stress relief annealed transformer cores, a semi organic or organic coating for stamped motor laminations. Coating thickness, insulation resistance and weldability all follow from the coating choice, and a coating intended for one process can be wrong for another.
Mechanical properties and workability
For motor laminations, specify the yield strength and the punchability, since a harder grade punches with more burr and tool wear. For high speed rotors, higher strength grades are needed to resist centrifugal stress.
Verification steps for incoming electrical steel
- Confirm the grade designation and the loss figure against the mill certificate, and check that the quoted loss includes its test condition.
- Verify thickness and thickness uniformity across the coil, because these drive loss and stacking factor.
- Check the coating type and the insulation resistance against the requirement for your process.
- Measure magnetic induction if the core size depends on it.
- Run a lamination trial for motor grades to confirm burr level and tool wear behaviour.
- Confirm that stress relief annealing, if used, is compatible with the coating.
Common sourcing mistakes
- Comparing core loss figures quoted at different thicknesses or inductions as if they were equivalent.
- Specifying grain oriented material for a motor, or non oriented for a transformer core, without matching the flux path.
- Choosing coating for price without confirming compatibility with the heat treatment or the punching process.
- Ignoring thickness tolerance, then finding the stacking factor does not meet the design.
- Selecting on loss alone without checking the mechanical strength needed for a high speed rotor.
Sourcing electrical steel from Hunan and China
China is a major producer of electrical steel across grain oriented and non oriented grades, including the thin, high strength grades used in traction motors, supported by large transformer and motor industries. Hunan hosts advanced steel suppliers within its advanced materials base. LiiFoo maintains verified supplier profiles in the advanced steel materials cluster covering electrical steel and magnetic materials.
For grade matched quotations, mill certificates and sample coils, see the cluster above or contact our sourcing team.
发表回复