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The large, aligned grains of grain oriented electrical steel are what give it low core loss along the rolling direction. Photo: Zureks, CC BY-SA 3.0, via Wikimedia Commons.
Buying grain oriented electrical steel (CRGO) from China: common grades and thicknesses, the specs to put in your order, and what to check before you pay.
Grain oriented electrical steel, also called CRGO (cold rolled grain oriented), is the core material of power and distribution transformers. Its job is to carry magnetic flux with as little loss as possible, so the numbers that matter are core loss and permeability, not only thickness and width.
What Chinese mills usually supply
| Item | Common options |
|---|---|
| Type | Conventional grain oriented (CGO) and high-permeability (Hi-B) |
| Thickness | 0.23 mm, 0.27 mm and 0.30 mm; 0.35 mm for some uses |
| Form | Full-width coils, or coils slit to your core width |
| Surface | Insulation coating on both sides |
Specs to put in your order
- Standard and grade, for example GB/T 2521.2, IEC 60404-8-7, ASTM A876 or JIS C 2553, with the grade name used by the mill.
- Maximum core loss in W/kg at 1.7 T and 50 Hz (P1.7/50), and minimum magnetic polarization at 800 A/m (B800).
- Thickness, width or slit width, coil inner diameter and maximum coil weight.
- Whether laser-scribed (domain refined) material is acceptable or required.
- Packing for sea freight. CRGO must stay dry: ask for sealed, moisture-protected packing.
Prime or secondary: put it in writing
Secondary CRGO (rejected or off-specification coils) sells much cheaper, and it is sometimes passed off as prime. Your contract should say prime material, and your inspector should take samples and have the core loss tested (Epstein test) against the mill test certificate.
Importing into India: check the BIS licence first
CRGO imported into India must be covered by a BIS licence for IS 3024 held by the producing mill. Ask for the mill's licence number and check it before you sign. Material without a valid licence can be held at Indian customs.
How to order through SinoAli
Send us the grade or the core loss you need, thickness, width, quantity and destination port. Ask us which mill the material comes from and which certificate it carries. When your contract is with SinoAli, you pay the deposit only to the company account named in your contract, you choose the inspection company, and you pay the balance after you have seen the inspection report. Buying from a new supplier for the first time? Read How to buy steel from China without getting scammed.
