High-permeability GO (HiB) steel — quick answer
Quick answer: B23P085 / B27P090 is Baosteel's high-permeability grain-oriented electrical steel (HiB class) in 0.23 mm and 0.27 mm. Magnetic domain control and surface treatment raise minimum polarization to J800 = 1.90 T (0.05 T above conventional GO), while no-load loss stays at maximum 0.85–0.89 W/kg at 1.7 T / 50 Hz (P1.7/50). Higher permeability means lower exciting current and lower noise in service — the grade power-transformer builders choose for large core-form units, HV bushings duty and heavily loaded network transformers.
How to read the grade designations
The designation follows Q/BQB 485-2023 for high-permeability grades. In B23P085: B = Baosteel, 23 = 0.23 mm nominal thickness, P = high permeability (高磁感), 085 = nominal specific total loss 0.85 W/kg at 1.7 T / 50 Hz. In B27P090: 27 = 0.27 mm, 090 = nominal loss 0.90 W/kg. Older Chinese notation uses the QG suffix (23QG085, 27QG090) for the same HiB family. Don't confuse the P (high-permeability) series with the R series: P-type maximizes magnetic polarization (lower exciting current, lower noise), while the R series (domain-refined, e.g. B23R080) minimizes loss — and its RD sub-series (B23RD070/080) is dedicated to distribution transformers. For the domain-refined family see B20R070 / B23R080 / B30R090.
Magnetic properties (per Baosteel Q/BQB 485-2023)
| Grade | Nominal thickness (mm) | Max core loss P1.7/50 (W/kg) | Min polarization J800 (T) | Min stacking factor |
|---|---|---|---|---|
| B23P085 / 23QG085 | 0.23 | 0.85 | 1.90 | 0.95 |
| B23P090 / 23QG090 | 0.23 | 0.88 | 1.89 | 0.95 |
| B27P090 / 27QG090 | 0.27 | 0.89 | 1.90 | 0.96 |
| B27P095 / 27QG095 | 0.27 | 0.93 | 1.90 | 0.96 |
| B30P105 / 30QG105 | 0.30 | 1.01 | 1.90 | 0.96 |
Typical (non-guaranteed) values for B23P085: P1.7/50 ≈ 0.82 W/kg, J800 ≈ 1.91 T. GO grades are measured at 1.7 T / 50 Hz. Every quotation includes guaranteed values per heat number.
International grade correspondence
| China Q/BQB 485-2023 | IEC 60404-8-7 style (class) | Note |
|---|---|---|
| B23P085 / B23P090 (23QG085/090) | 085-23H / 090-23H | 0.23 mm high-permeability band |
| B27P090 / B27P095 (27QG090/095) | 090-27H / 095-27H | 0.27 mm high-permeability band |
| B30P105 (30QG105) | 105-30H | 0.30 mm high-permeability band |
Class correspondence for reference only — test conditions and guaranteed values differ between standards. Confirm the exact grade on the mill test certificate before ordering. See our full steel grade equivalent charts.
Typical applications
HiB steel is the default core material for power transformers: 110 kV–500 kV grid transformers, large distribution substations, furnace and rectifier transformers, phase shifters and HVDC converter transformers, plus large hydro/generator step-up units. The higher J800 lets designers run cores at higher operating induction (typically 1.7–1.8 T vs 1.6–1.7 T for conventional GO), shrinking core cross-section, copper weight and tank size — compounding savings that dominate the economics of large units. Lower exciting current also improves voltage regulation under load and reduces harmonic distortion in converter duty. Utility specifiers in markets modernizing their grids — Latin America, Southeast Asia, the Middle East, Africa — increasingly write HiB grades into transformer procurement.
Supply form, coating and packaging
Supplied as wide coils or slit to lamination width: typical coil weight 2–6 t, inside diameter 508/510 mm, standard widths 900–1,250 mm. Coatings per Q/BQB 485-2023: S (tension inorganic, withstands 850 °C stress-relief annealing) and H (chrome-free); HiB product is supplied with the coating applied after magnetic-domain treatment to lock in permeability. Export packaging: rust-proof paper + steel strapping + desiccant, eye-to-wall loading; wide coils can be shipped as eye-to-sky on skids for special container arrangements. Every coil ships with the original Baosteel mill test certificate (loss and polarization per heat number).
Why Baosteel, why Baohui
HiB production requires end-to-end magnetic-texture control that only a handful of mills worldwide have mastered; Baosteel's P-series delivers 1.90 T polarization at industrial scale and competitive pricing versus Japanese and Korean HiB. As a Baosteel channel partner, Baohui Steel supports power-transformer builders from grade selection (23P085 vs 27P090 vs domain-refined RD for a given design) through slitting, consolidation and documentation. Send your core design, target induction, width and quantity for a firm FOB Shanghai quotation within 24 hours.
