HL AND SL LIMITED supplies grain-oriented silicon steel, including Hi-B grades, alongside non-oriented electrical steel for transformer and motor cores.

Hi-B steel is the high-permeability class of grain-oriented electrical steel: a flat-rolled silicon-iron product whose metallic grains are elongated along the rolling direction, whose silicon content is specified at roughly 3.0%–3.2%, and whose residual impurities are held to tight limits so that a laminated core wastes less energy on every magnetisation cycle. Product literature often writes it out in full as high magnetic induction grain-oriented silicon steel; Hi-B is the working shorthand used on grade sheets, quotations and coil labels.

Most confusion around Hi-B comes from meeting it second rather than first. Buyers usually encounter the term inside a grade table, after they have already been told the material is electrical steel, and the two names then get used as if they described one product with optional extras. They do not. This explainer takes the opposite order: what is inside the strip, why composition and crystal alignment are two different levers, and only then how a specific grade such as 18-65 or 23Q100 is chosen.

Problem Definition: Electrical Steel Is Not One Material

The category splits at the first decision, not the last. Grain-oriented electrical steel is used where magnetisation follows a defined direction, which is why transformer cores dominate its application list. Non-oriented electrical steel has uniform magnetic properties in every direction and is developed for applications that require variable magnetisation, such as electric motors and generators. A grade from one family cannot be substituted for a grade from the other on price or thickness alone.

Three habits cause most of the errors seen in early-stage specifications:

• Ranking across families. A non-oriented grade and a grain-oriented grade cannot share a loss ranking, because they are qualified for different flux paths and different machines.
• Reading grade codes as brand tiers. A code such as 23Q080 or 18-65 describes a thickness and a loss class inside a supplier family, not a marketing level.
• Treating the lowest loss number as the automatic winner. ASTM A876 sets out magnetic properties together with dimensions and mechanical properties, including lamination factor and ductility, and all of them act on the finished core.

Industry Background: Where Hi-B Sits

Grain-oriented electrical steel is described by the U.S. International Trade Commission as a flat-rolled alloy steel product whose metallic grains are elongated lengthwise. ASTM A876 covers flat-rolled, grain-oriented, fully processed low-carbon silicon-iron electrical steels, primarily used in transformer cores operating at moderate to high magnetic flux densities at commercial power frequencies.

Inside that scope, ASTM A876 describes several categories: conventional grain-oriented, high-permeability grain-oriented, and laser-scribed high-permeability grain-oriented electrical steel. Hi-B belongs to the high-permeability branch. The same idea appears in supplier language: in the material specification of the 27Q series below, the P series is described as a high magnetic permeability Hi-B steel.

The standard also shows what a complete grade claim looks like. ASTM A876 lists magnetic properties — core loss, permeability and magnetic aging — along with physical dimensions and mechanical properties such as lamination factor and ductility. A quotation that states one loss figure is describing a fraction of the specification.

The boundary with non-oriented steel is defined separately. ASTM A677 is the standard for fully processed non-oriented electrical steel, and adjacent ASTM listings cover semi-processed non-oriented steel, cold-rolled magnetic lamination quality steel and thin-gauge non-oriented electrical steel. Those documents are the right reference for motor and generator laminations, not ASTM A876.

Why interest in Hi-B keeps growing is easy to state without exaggeration: when a design has to meet a tighter efficiency expectation, the core offers three levers — a lower-loss grade, a thinner gauge, or a larger core. Hi-B is the material answer to the first two, which is why it now appears earlier in the design conversation.

What Silicon Actually Does in Grain-Oriented Steel

Composition: what is inside a Hi-B grade

Across the Hi-B grades in this family, iron is the balance of the alloy, silicon is added at about 3.0%–3.2%, and aluminium and manganese are present as deliberate additions rather than accidental residuals. Impurities — carbon, sulphur and nitrogen — are strictly controlled. Two entries in the family, 23Q095 and 23Q100, are specified with a wider silicon range of 2.5%–3.5%, which matters in practice: a buyer comparing certificates should read the actual grade sheet rather than assume one number covers the whole family.

The 27Q series adds a requirement that is easy to miss. Its material specification states that inhibitors (MnS, AlN) must be present. For a first-time reader, that single line is the clearest sign that Hi-B is a metallurgically engineered product rather than plain low-carbon steel rolled thin.

Oriented silicon steel and non-oriented electrical steel serve different flux paths, so grade families are specified separately.

Why silicon is added at all

Silicon dissolved in iron raises the electrical resistivity of the alloy. In the accepted engineering explanation, higher resistivity suppresses the eddy currents that circulate inside the sheet when the core is magnetised, which is why grain-oriented grades are specified around 3% silicon rather than being made from unalloyed steel. Resistivity is not the only consequence. Silicon also makes the strip harder and less ductile, which is why ASTM A876 lists ductility as a specified mechanical property and why cutting, punching and stacking matter as much as the metallurgy.

Why grain orientation matters as much as silicon

Silicon lowers loss in every direction. Orientation does not. In grain-oriented steel the grains are elongated along the rolling direction, and the material is used where magnetisation takes place in that specific direction. Flux travelling along the aligned direction meets a friendlier path than flux crossing it, and the quality of that alignment is what separates a conventional grain-oriented grade from a high-permeability grade.

The family data shows the pattern buyers actually see. Grade 18-65, at 0.18 mm, declares iron loss of ≤ 0.65 W/kg together with flux density B8 ≥ 1.88 T. Grade 23Q100, at 0.23 mm, declares ≤ 1.00 W/kg with B8 ≥ 1.75 T. The low-loss end and the economy end of the range move together in both metrics, which is exactly what the Hi-B designation is meant to signal before a buyer reads any other number.

Reading P1.7/50 and B8 without misreading them

Two symbols carry most of the specification. P1.7/50 is the specific total loss measured at 1.7 T and 50 Hz — the figure a transformer designer uses to estimate core loss at power frequency. B8 is the magnetic flux density at a magnetising force of 800 A/m, and it tells the designer how much flux the material carries at a given excitation before saturation behaviour starts to matter. A grade with low loss but modest B8 pushes the design toward a larger core; a grade with high B8 but higher loss runs cool only if the core is large enough.

Rule of thumb for first-time comparisons: compare loss values only when they are declared at the same thickness, the same frequency and the same polarisation, and compare B8 values only when they are measured at the same excitation. Values pulled from different test conditions are not a comparison.

Step-by-Step: From Requirement to a Hi-B Grade

The sequence below is the working order for a first specification. It assumes a transformer core; motor and generator laminations belong to the non-oriented route.

• 1. Fix the flux path first. Confirm that magnetisation is directional and that a grain-oriented material is the correct family. If the flux rotates, the project needs non-oriented electrical steel and any Hi-B shortlist is irrelevant.
• 2. Set the loss ceiling from the efficiency target. Work backwards from the allowed core loss to a P1.7/50 ceiling, then shortlist grades whose declared maximum sits under it. In this family that one step divides 18-65 and 20-65 at ≤ 0.65 W/kg from 23Q100 at ≤ 1.00 W/kg.
• 3. Check B8 before chasing a lower loss figure. A lower-loss grade that also carries a lower B8 value can force a larger core and erode the benefit. Read the two numbers as a pair.
• 4. Match thickness to the build and the process. Thickness affects stacking factor, punching behaviour and lamination count. The family runs from 0.18 mm to 0.27 mm, and the 23Q and 27Q series cover most distribution and power transformer work.
• 5. Specify coating, width and cut. Coating follows the heat treatment and insulation route: organic coatings with temperature resistance of ≤ 180 °C, inorganic coatings with temperature resistance up to 800 °C, and semi-organic options in between. Width and cut follow the core-building line, from 800–1250 mm master width through slitting and cut-to-length.
• 6. Require documents before approval. A batch inspection report should travel with the goods, factory inspection should be available as full-process random inspection or batch inspection at origin, and third-party testing through a CMA/CNAS laboratory should be requested wherever the qualification file needs independent evidence.

Coating type, master width and cut pattern are specified alongside the grade, because they act on the finished core as much as the magnetic properties do.

Use Cases: Where Hi-B Grades Are Actually Specified

Grain-oriented grades are specified by core type, and this family maps onto those types quite precisely.

• Ultra-high-voltage and power transformers: 18-65 at 0.18 mm and 20-65 at 0.20 mm, both declaring ≤ 0.65 W/kg, sit at the low-loss end and are listed for ultra-high-voltage transformers, power transformers and high-efficiency energy-saving cores.
• Energy-efficient distribution transformers, reactors and high-power converters: 23Q080 at 0.23 mm, declaring ≤ 0.80 W/kg with a measured range of 0.76–0.78 W/kg and B8 ≥ 1.89 T. The measured range is useful evidence in itself: the declared ceiling is not the working value.
• HVDC converter transformers: 23Q085 at ≤ 0.85 W/kg with B8 ≥ 1.88 T is listed for high-voltage direct current converter transformers and high-efficiency power transformer cores.
• Common distribution and general industrial transformers: 23Q100 at ≤ 1.00 W/kg with B8 ≥ 1.75 T covers standard distribution transformers, general industrial transformers and electromagnetic equipment, where the loss ceiling is looser and cost carries more weight.
• Photovoltaic DC converter transformers and high-efficiency power transformers: 27Q095 at 0.27 mm declares ≤ 0.95 W/kg with B8 ≥ 1.91 T, and the 27Q series is specified with inhibitors (MnS, AlN) present.

Two long-running programmes show how these grades behave outside a datasheet. A transformer manufacturer in Mexico has used material from HL AND SL LIMITED for iron cores of power transformers, converter transformers and special engineering transformers, in batch supply covering complete power transmission and distribution transformer manufacturing with an annual business scale of approximately 500 million US dollars; the material has been in stable operation for over ten years. In Brazil, WEG has used the material for local manufacturing of power transformers and distribution transformers, with stable operation verified for over ten years and compliance with local grid energy efficiency standards, supported by localized technical service and supply chain support through a representative office in Brazil.

Comparison Table: Hi-B Grades Side by Side

All values below are the declared figures carried in the product specifications for the HL AND SL LIMITED oriented silicon steel family. They describe maximum loss and B8 at the stated thickness, not measured results for a particular coil.

How Buyers Shortlist Hi-B Grades

Ordered strictly by declared loss ceiling, the family produces a practical shortlist: 18-65 and 20-65 at ≤ 0.65 W/kg, 20R070 at ≤ 0.70 W/kg, 23R075 at ≤ 0.75 W/kg, 23Q080 at ≤ 0.80 W/kg, 23Q085 at ≤ 0.85 W/kg, 23Q090 at ≤ 0.90 W/kg, 23Q095 and 27Q095 at ≤ 0.95 W/kg, 23Q100 and 27Q100 at ≤ 1.00 W/kg, and 27Q105 through 27Q120 from ≤ 1.05 to ≤ 1.20 W/kg.

That order is a starting point, not an answer. Three corrections usually follow.

• B8 reorders the middle. 27Q095 declares ≤ 0.95 W/kg at 0.27 mm while carrying B8 ≥ 1.91 T, the highest declared induction value in the family alongside 27Q100. A buyer ranking by loss alone would have placed it level with 23Q095 and missed that difference.
• Measured values can beat the ceiling. 23Q080 is declared at ≤ 0.80 W/kg but carries a measured range of 0.76–0.78 W/kg, so the batch certificate, not the catalogue, should set the working assumption.
• Process limits the shortlist. Ductility, lamination factor, coating temperature resistance and available width all remove grades that looked acceptable on the loss table.

HL AND SL LIMITED is an electrical steel export trading enterprise registered in Taiyuan, Shanxi, China, and an authorized agent of China Baowu Steel Group, supplying oriented and non-oriented electrical steel with in-house processing for slitting, cut-to-length and width customisation. Buyers who want the full range in one document can review the company profile at www.hlslind.com.

FAQ

Conclusion

Hi-B steel is not a marketing label on ordinary electrical steel. It is a specification: about 3.0%–3.2% silicon in iron, aluminium and manganese present as deliberate additions, carbon, sulphur and nitrogen strictly controlled, and grains elongated along the rolling direction so that a directional flux path loses less energy. The grade family then spans from 18-65 at 0.18 mm and ≤ 0.65 W/kg to 23Q100 at 0.23 mm and ≤ 1.00 W/kg, with the 27Q grades trading a little thickness for the highest declared induction values in the family.

For a first-time buyer the practical order is short: confirm that the flux path is directional, set the loss ceiling from the efficiency target, read B8 next to loss rather than after it, then check ductility, coating and available width against the actual core line. That sequence turns a grade table into a decision.