M19-class non-oriented electrical steel — quick answer
Quick answer: M19 is an AISI loss class for 0.35 mm non-oriented electrical steel. The Baosteel equivalents are 35WW300 (enterprise grade, max 2.65 W/kg P1.5/50) and B35A300 (GB/T 2521.1 grade, max 2.90 W/kg P1.5/50), also written 35W300 under GB/T 2521.1-2016. In EN 10106 designation this is the M300-35A class; the Japanese equivalent is JIS 35A300. It is the workhorse grade for EV drive motors, high-efficiency compressors, pumps and small transformers.
How to read the grade designations
Electrical steel grades encode thickness and core loss. In 35WW300: 35 = 0.35 mm nominal thickness, WW = conventional non-oriented (WH = high-efficiency), 300 = nominal loss 3.00 W/kg at 1.5 T / 50 Hz. In B35A300: B = Baosteel Q/BQB designation, 35 = 0.35 mm, A = conventional non-oriented, 300 = same nominal loss. In EN M300-35A: M300 = 3.00 W/kg loss class, 35 = 0.35 mm, A = insulation coating class. AISI M19 belongs to the same loss class but is specified in W/lb at 1.5 T / 60 Hz, so the numbers are not directly comparable.
Magnetic properties (per Baosteel Q/BQB 480-2023)
| Grade | Nominal thickness (mm) | Max core loss P1.5/50 (W/kg) | Min polarization J5000 (T) | Min stacking factor | Typical density (kg/dm³) |
|---|---|---|---|---|---|
| B35A250 | 0.35 | 2.45 | 1.64 | 0.95 | 7.60 |
| 35WW300 | 0.35 | 2.65 | 1.64 | 0.95 | 7.65 |
| B35A300 | 0.35 | 2.90 | 1.64 | 0.95 | 7.65 |
| 35WW360 | 0.35 | 3.20 | 1.65 | 0.95 | 7.65 |
| B35A440 | 0.35 | 3.40 | 1.67 | 0.95 | 7.70 |
Typical (non-guaranteed) values for 35WW300: P1.5/50 ≈ 2.51 W/kg, P1.0/50 ≈ 1.07 W/kg, P1.5/60 ≈ 3.07 W/kg. Full magnetic curves (J1000/J2500/J5000/J10000) ship with every quotation.
International grade equivalents
| China Q/BQB 480-2023 | China GB/T 2521.1 | EN 10106 | JIS C 2552 (class) | AISI (class) |
|---|---|---|---|---|
| B35A250 / 35WW250 | 35W250 | M250-35A | 35A250 | M15 |
| B35A300 / 35WW300 | 35W300 | M300-35A | 35A300 | M19 |
| B35A360 / 35WW360 | 35W360 | M330-35A | 35A360 | M22 |
| B35A440 / 35WW440 | 35W440 | M350-35A | 35A440 | M27 |
Class correspondence for reference only — test conditions differ between standards. Confirm the exact grade on the mill test certificate before ordering. See our full steel grade equivalent charts.
Typical applications
0.35 mm M19-class NGO steel is the standard choice for premium-efficiency motors: EV and hybrid drive motors, traction motors, refrigerator and air-conditioner compressors, pumps, servo motors and small distribution transformer cores. Its low specific total loss cuts no-load energy consumption, which is why efficiency-class motors (IE3/IE4/IE5) are built on 35WW300-class material rather than thicker 0.50 mm grades.
Supply form, coating and packaging
Supplied as slit coils: typical coil weight 2–6 t, inside diameter 508/510 mm, width on request (standard 900–1,250 mm). Standard insulation coatings include semi-organic C5/C6 and chrome-free types; self-bonding coatings available on request. Export packaging: moisture-proof paper + steel strapping, eye-to-sky or eye-to-wall container loading. Every coil ships with the original Baosteel mill test certificate (magnetic values per heat number).
Why Baosteel, why Baohui
Baosteel is China's largest and the world's leading electrical steel producer — more than half of China's EV drive motors run on Baosteel NGO steel. As a Baosteel channel partner, Baohui Steel quotes M19-class material ex-mill or ex-warehouse with the original MTC, handles cutting-to-length and export documentation, and answers grade-substitution questions (e.g. 35WW300 vs 50WW470 for a given motor design) with engineering support. Send your grade, thickness, width and quantity for a firm FOB Shanghai quotation within 24 hours.
