Silicon steel (Fe-Si electrical steel, typically 2.5–3.5 wt% Si) is the dominant soft-magnetic material for static and rotating energy equipment because its silicon content raises resistivity and suppresses eddy-current loss, at the cost of higher brittleness versus low-carbon steel [S2].
Selection for energy equipment is driven by three coupled parameters: grain orientation (GO vs NGO), core loss at the design flux density (commonly 1.5–1.7 T for power transformers), and lamination thickness (0.23–0.50 mm). A typical wholesale CRGO lamination listing on a major B2B portal in late July 2026 sat at roughly US$3,000 per lot for oriented high-strength transformer core laminations, indicating that supply remains broadly available but price-quoted per specification rather than per grade alone [S2].
CRGO vs CRNGO: the two-grade decision at a glance
CRGO (cold-rolled grain-oriented) silicon steel is processed to align the Goss texture (110)[001] cube-on-edge) so that the rolling direction carries an order-of-magnitude higher permeability than the transverse direction, which is why transformer cores are wound or step-lapped along that axis [S2].
CRNGO (cold-rolled non-oriented) silicon steel has a near-isotropic magnetic texture and is the workhorse for rotating machines (induction motors, large generators) where flux rotates through the lamination plane, and is also widely listed for general industrial magnetic cores on B2B directories in 2026 [S1]. For a deeper side-by-side of these two grades in motor and transformer contexts, the CRGO vs CRNGO selection map walks through the permeability and cost trade-offs in more detail. Practical rule for the spec sheet: specify CRGO when flux is unidirectional and core loss at 1.7 T is the bottleneck; specify CRNGO when flux is rotating or reversing, and punching/blanking cost dominates.
Loss budget: W/kg at 50/60 Hz and the 0.23 mm boundary
Total core loss P_total = P_h + P_e + P_a, where P_h scales with frequency, P_e scales with frequency squared and thickness squared, and P_a is the anomalous excess loss. Because P_e grows with lamination thickness squared, dropping thickness from 0.35 mm to 0.23 mm roughly cuts eddy-current loss by a factor of 2.3 for the same grade and frequency [S1].
Transformer-grade CRGO commonly ships at 0.23, 0.27, 0.30, or 0.35 mm; motor-grade CRNGO commonly ships at 0.35, 0.50, or 0.65 mm. The thinnest grades (0.23 mm, often called "HiB" or domain-refined) are specified where the no-load loss target is tight, but they are more expensive per kilogram and harder to punch without burr. For most distribution-class transformers the practical sweet spot remains 0.30–0.35 mm CRGO, balancing loss, cost, and manufacturability [S2].
Energy-equipment use cases: transformer, motor, reactor
Power and distribution transformers are the largest single end-use of CRGO: a 50 kVA–2.5 MVA distribution transformer typically specifies 0.30 mm CRGO with a core loss target of roughly 0.9–1.2 W/kg at 1.7 T and 50 Hz, with the wound or step-lapped core cut along the rolling direction to exploit the Goss texture [S2]. For high-speed traction motors and rail traction, the relevant constraint shifts from peak flux density to high-frequency loss; a complementary reference on rail traction motor silicon steel grades, gauges, and loss maps covers the rotating-machine end of the same problem.
Rotating machines (industrial induction motors, wind turbine generators) use CRNGO at 0.35–0.50 mm, where the magnetic flux rotates in the lamination plane, so the anisotropy of CRGO is wasted and CRNGO's isotropic permeability gives a better mean performance across the stator teeth and yoke [S1]. For oil-and-gas upstream and downstream energy assets, the silicon steel spec map and material gates covers the additional NACE MR0175 / H₂S-environment constraints on motor laminations in sour service. Reactors and chokes use either grade, sized by the AC flux swing rather than the operating flux density, and often use grain-oriented material with a distributed gap to suppress DC bias.
Selection criteria: Si content, gauge, coating, annealing
Si content is the first gate: 2.5–3.5 wt% Si is the industrial norm, with 3.0 wt% being a common middle for CRGO and 2.5–3.0 wt% common for CRNGO. Higher Si increases resistivity and lowers magnetostriction but also raises brittleness; above roughly 3.5 wt% Si the alloy becomes hard to cold-roll, which is why thinner high-grade CRGO is made by a special two-stage cold-rolling route [S1].
Lamination thickness is the second gate. Standard motor and small-transformer gauges are 0.35 mm, 0.50 mm, and 0.65 mm; high-efficiency and high-frequency designs drop to 0.27 mm, 0.23 mm, and even 0.20 mm. Insulating coating is the third gate: C3 (chromate-free, the modern default for RoHS and REACH compliance), C4 (for higher annealing temperatures), and C5 (for very high punchability) are the coating families most commonly seen in 2026 supplier listings on industrial B2B portals [S2]. Stress-relief annealing after punching (typically 750–800 °C in a decarburising or inert atmosphere for NGO, 800–850 °C for GO with magnesia-bearing insulation intact) is required for CRGO wound cores, and is often recommended for high-efficiency CRNGO stator stacks as well.
Who silicon steel is for (and who it is not for)
Silicon steel is the right choice for 50/60 Hz power transformers, distribution transformers, traction transformers, large industrial induction motors, wound-rotor synchronous machines, and magnetic chokes/reactors in the kW–MVA range where laminated cores are needed to carry AC flux [S1][S2].
It is not the right choice for high-frequency (kHz) magnetic components, where ferrite, amorphous ribbon, or nanocrystalline ribbon dominate; for very high DC-flux applications (chokes carrying tens of amps DC) where a distributed air gap or powder-core material is specified; or for very small signal transformers (mains-isolated signal, audio) where the cost of grain-oriented material cannot be justified. Anyone spec'ing below roughly 400 Hz and above roughly 10 kVA should look at silicon steel first; above 1 kHz, move to ferrite or amorphous.
Failure modes and constraints: burr, stress, and welding
Punching burr over roughly 30 µm on a 0.23 mm lamination can short the interlaminar insulation and raise eddy-current loss by 10–20% under load, so laser-cut or wire-EDM stacks are common for very thin CRGO, and C5-class coatings are specified for tight burr tolerance [S2].
Residual stress from stamping raises hysteresis loss; a 180° bend radius below roughly 2× the lamination thickness on 0.23 mm CRGO is enough to degrade permeability at the bend and force a stress-relief anneal downstream. Welding on the lamination edges (for stacked-core frames) injects heat-affected zones where the grain structure is locally destroyed, so seam welding and laser welding are typically restricted to the outside 1–2 mm of the stack end and away from the active flux path.
Standards, sourcing, and where the 2026 supply sits
CRGO and CRNGO are commonly delivered to GB/T 2521 (China), ASTM A677 / A683 (USA), EN 10106 / EN 10107 (Europe), and JIS C2552 / C2553 (Japan); the magnetostriction and loss limits are grade-specific within each of these, so the call-out should always include the grade code (e.g. 30Q120 for 0.30 mm, 1.20 W/kg at 1.7 T, 50 Hz) [S2].
For related context on how laminations are punched and stacked, see the magnesium die casting machine selection for aerospace components reference, which covers die-casting of motor housings that mate directly to CRNGO stacks. The 2026 B2B sourcing landscape on Made-in-China.com lists multiple audited suppliers of customized CRGO high-strength transformer core laminations and a wide range of CRNGO Ei-cores, CRGO coils, and cold-rolled electrical silicon steel in 0.23–0.50 mm gauges, with the cheapest wholesale CRGO lots in late July 2026 around US$3,000 per lot and pricing per specification rather than per grade alone [S2].
Trackable signals: (1) the spread between 0.23 mm HiB CRGO and 0.35 mm standard CRGO on B2B portals in 2026, which is the main cost driver in low-loss transformer tenders; (2) availability of C3 chromate-free coatings on Chinese mill listings, which is the gating factor for RoHS/REACH-bound EU energy-equipment projects; and (3) incremental supply of 0.20 mm and thinner CRGO from Chinese mills, which would shift the high-frequency end of the energy-equipment market off ferrite in some kHz-class applications.
The underlying component specifications are covered under silicon steel, energy management, and energy meter.