Electrical steel core loss is generated when the material is repeatedly magnetized during operation. Hysteresis loss is one part of this total loss, while eddy-current loss arises from a different physical mechanism.

The distinction matters because hysteresis and eddy-current losses respond differently to material structure and operating conditions.

In motors, generators, and transformers, hysteresis behavior depends on the electrical steel grade, microstructure, residual stress, and processing history.

This article explains what hysteresis loss is, what changes it, why cutting and stamping can affect it, and what buyers and engineers should look for beyond a single datasheet loss value.

Key Takeaways

Hysteresis loss is energy dissipated during repeated magnetization and demagnetization of electrical steel.
Hysteresis loss is different from eddy-current loss, which results from electrical currents induced within the conductive steel by a changing magnetic field.
Grain size, crystallographic texture, impurities, and residual stress can all influence hysteresis loss.
Cutting and stamping can introduce residual stress and plastic deformation near the edges, locally degrading magnetic performance and increasing hysteresis loss.
Datasheets typically report total core loss under defined test conditions rather than hysteresis loss alone. Where hysteresis behavior matters, B-H characteristics, coercivity, permeability, and processing condition can provide additional information.

Hysteresis Loss vs Eddy-Current Loss

Hysteresis loss vs eddy-current loss in electrical steel with B-H loop and lamination comparison

Core loss represents magnetic energy dissipated in electrical steel during alternating magnetization. Hysteresis loss and eddy-current loss arise from different physical mechanisms. Hysteresis loss is associated with energy dissipated as magnetic domains and domain walls respond to a changing magnetic field. The energy dissipated during each magnetization cycle is related to the area enclosed by the material's B-H hysteresis loop.

Eddy-current loss results from electrical currents induced within the conductive steel by the changing magnetic field. It is strongly influenced by sheet thickness, electrical resistivity, magnetic flux density, and frequency.

The table below compares hysteresis loss with eddy-current loss.

Feature	Hysteresis Loss	Eddy-Current Loss
Physical origin	Magnetic domain and domain-wall behavior during cyclic magnetization	Electrical currents induced within the conductive material
Strongly influenced by	Coercivity, grain structure, crystallographic texture, stress, impurities	Sheet thickness, electrical resistivity, frequency, magnetic flux density
Common ways to reduce it	Material and texture control, lower residual stress, suitable annealing	Thinner laminations, higher electrical resistivity, effective interlaminar insulation

What Changes Hysteresis Loss in Electrical Steel?

Hysteresis loss is closely related to the microstructure and magnetic condition of the electrical steel.

Grain Size and Crystallographic Texture

Electrical steel consists of microscopic crystalline grains. Grain boundaries can hinder domain-wall movement, so grain size can influence hysteresis loss.

In many electrical steels, increasing grain size can reduce the hysteresis component of loss. However, larger grains are not universally better because grain size also affects other dynamic loss components and the optimum structure depends on the material and operating condition.

Alloying Elements (Mainly Silicon)

Silicon is added to electrical steel primarily to increase electrical resistivity and improve magnetic performance. Higher resistivity helps reduce eddy-current loss, while alloy composition also influences the material's microstructure and hysteresis behavior.

Increasing silicon content can improve electrical resistivity, but it also reduces ductility and makes rolling and downstream processing more difficult.

Internal Stress and Material Purity

Residual stress can restrict domain-wall movement and degrade magnetic properties. It may be introduced during rolling, leveling, or downstream processing.

Impurities, inclusions, and second-phase particles can also act as obstacles to domain-wall movement, depending on their type, size, and distribution.

These microstructural obstacles can pin domain walls and increase the field required for magnetization reversal, contributing to higher hysteresis loss.

In applications where processing introduces significant residual stress, a suitable annealing treatment may be used to recover part of the magnetic performance.

Why Cutting and Stamping Can Increase Hysteresis Loss

Cutting and stamping can create an affected zone near the processed edge where plastic deformation, residual stress, and microstructural changes alter magnetic behavior and restrict domain-wall movement.

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Cutting and stamping effects on hysteresis loss in electrical steel laminations

The affected region can therefore show higher coercivity and hysteresis loss than the undisturbed material. The effect becomes more important when a large proportion of the magnetic path lies close to processed edges, such as in narrow motor teeth or thin geometries.

Where appropriate, stress-relief annealing can reduce processing-induced stress and recover part of the magnetic performance.

GOES vs. NGOES: Different Materials, Different Hysteresis Behavior

Grain-oriented electrical steel (GOES) and non-grain-oriented electrical steel (NGOES) are engineered with different crystallographic textures because they serve different magnetic-field conditions.

Grain-Oriented Electrical Steel (GOES)

GOES is processed to develop a strong preferred crystallographic texture. Its magnetic properties are optimized along the rolling direction, allowing low-loss magnetization when the flux follows that preferred direction.

This directional behavior makes GOES particularly suitable for transformer cores and other applications where the magnetic flux follows a predominantly defined path.

Non-Grain-Oriented Electrical Steel (NGOES)

NGOES is designed for more uniform magnetic behavior within the sheet plane rather than for one strongly preferred magnetization direction. This makes it suitable for rotating electrical machines, where the direction of magnetic flux changes during operation.

Hysteresis performance should therefore be compared under the magnetic direction and operating conditions relevant to the application.

Beyond the Data Sheet: What to Actually Check

Electrical steel datasheets typically report specific total loss under defined magnetic test conditions. For example, P1.5/50 represents total loss measured at 1.5 T and 50 Hz.

This value does not normally show the hysteresis component separately.

Two materials can show similar total-loss values under one test condition while differing in coercivity, permeability, microstructure, and the relative contribution of different loss mechanisms.

This becomes more relevant when the actual operating frequency or magnetic loading differs from the datasheet test point.

What Buyers and Engineers Should Check

B-H Loop and Coercivity: Where hysteresis behavior is important, ask whether B-H loop or coercivity data are available. A narrower hysteresis loop and lower coercivity generally indicate less energy dissipated during a magnetization cycle.
Loss Data at Relevant Frequencies: For applications operating beyond standard power frequency, compare total-loss data at relevant flux-density and frequency conditions. Loss-separation data can provide additional insight where available.
Material Grade and Processing Condition: Confirm the exact grade, thickness, delivery condition, and any relevant annealing requirements. These factors influence the magnetic condition of the material supplied and how it responds to downstream processing.
Permeability: Permeability data help show how readily the material responds to an applied magnetic field. It should be considered together with core loss, coercivity, and the required operating flux density rather than used as a standalone indicator of hysteresis loss.

For routine material comparison, buyers usually start with grade, thickness, total core loss at the required test point, and the applicable standard. More detailed magnetic data become useful when the application places tighter demands on hysteresis behavior.

Conclusion

Hysteresis loss in electrical steel is closely tied to microstructure, magnetic texture, stress, and processing history.

Where it matters to the application, coercivity and B-H characteristics can provide useful context beyond the total core-loss value.

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