M270-35A
1.0801
Cold-rolled non-oriented electrical steel, fully processed · EN 10106:2015 · IEC 60404-8-4:2022+A1:2026
M270-35A is a 0.35 mm fully processed non-oriented electrical steel defined primarily by magnetic performance rather than a fixed chemical composition. EN 10106 limits its aged specific total loss to 2.70 W/kg at 1.5 T and 50 Hz and specifies minimum polarization, stacking factor, loss anisotropy and bend performance. The designation alone does not guarantee mechanical strength, high-frequency loss, coating performance or finished-core behavior, all of which may require additional purchasing requirements and validation after lamination manufacture.
- 0.35 mmNominal thickness · Encoded by “35” in the grade name.
- 2.70 W/kg at 1.5 T, 50 HzMaximum specific total loss · Specified for standardized Epstein testing in the aged condition; “270” encodes this ceiling.
- 1.49 / 1.60 / 1.70 TMinimum magnetic polarization · At peak magnetic field strengths of 2,500 / 5,000 / 10,000 A/m, respectively.
- 0.95Minimum stacking factor · Coating type and thickness still affect the practical build and effective iron section of a finished core.
- ±17%Maximum loss anisotropy · Non-oriented does not mean perfectly isotropic.
- Performance-based, not composition-basedMetallurgical definition · The standard leaves production route and chemical composition to the manufacturer.
Overview
- Designation system
- Steel name to EN 10027-1; steel number to EN 10027-2
- Product forms
- Cold-rolled strip supplied in coils, Cold-rolled sheet supplied in bundles
- Condition
- Fully processed/finally annealed, Uncoated or insulation-coated on one or both sides, Specified maximum loss applies in the prescribed aged test condition
- Density
- 7.65 g/cm³ (Conventional density used by EN 10106 for magnetic-property calculations; it is not necessarily the measured physical density of every product.)
Designation, scope and standard status
The EN designation is decoded as follows: “M” identifies electrical steel; “270” is 100 times the maximum specified specific total loss in W/kg at 1.5 T and 50 Hz; “35” is 100 times the nominal thickness in millimetres; and “A” identifies cold-rolled non-oriented material supplied in the fully processed state. Steel number 1.0801 identifies the same EN grade.
EN 10106:2015 remains the governing European product standard as of September 30, 2026 and covers fully processed cold-rolled non-oriented electrical steel sheet and strip. A 2026 revision is under development, but a draft should not be used as the contractual basis unless expressly agreed. The current international counterpart is IEC 60404-8-4:2022+A1:2026, where the corresponding frequency-explicit designation is M270-35A5; the final “5” denotes the 50 Hz classification frequency.
The scope is material for magnetic circuits in its final mill-annealed condition. It does not cover semi-processed electrical steel requiring the user to develop final magnetic properties by annealing.
Specified magnetic and technological requirements
| Characteristic | Requirement | Applicability |
|---|---|---|
| Nominal thickness | 0.35 mm | Product classification thickness |
| Specific total loss | ≤ 2.70 W/kg | At peak polarization 1.5 T and 50 Hz; aged condition |
| Magnetic polarization J | ≥ 1.49 T | At 2,500 A/m and 50 Hz |
| Magnetic polarization J | ≥ 1.60 T | At 5,000 A/m and 50 Hz |
| Magnetic polarization J | ≥ 1.70 T | At 10,000 A/m and 50 Hz |
| Loss anisotropy | Within ±17% | At 1.5 T and 50 Hz |
| Stacking factor | ≥ 0.95 | Standard material requirement; practical stack build also depends on coating |
| Reverse bends | ≥ 2 | Number before first visible base-metal crack or fracture |
| Conventional density | 7.65 kg/dm³ | Used for standardized property determination |
These are grade requirements, not representative producer averages.
| Test point | EN 10106 guidance value | Status |
|---|---|---|
| 1.0 T, 50 Hz | 1.10 W/kg maximum | Informative; not the defining grade requirement |
| 1.5 T, 60 Hz | 3.36 W/kg maximum | Informative in EN 10106 and IEC 60404-8-4; verify if a contractual 60 Hz guarantee is required |
Values at other frequencies, polarizations or waveforms are not established by the M270-35A designation.
The standardized magnetic values are determined using Epstein-frame specimens prepared and measured under the applicable IEC 60404-2 procedures. They qualify the supplied flat product under controlled laboratory conditions; they do not directly guarantee the loss or magnetizing current of a punched, welded, interlocked, shrink-fitted or otherwise assembled production core.
What the grade does not define
M270-35A is not a composition grade in the structural-steel sense. Its chemical composition and production route are left to the manufacturer, provided that the delivered product meets the specified magnetic, dimensional and technological requirements. Silicon, aluminium, carbon and other constituents therefore should not be assigned fixed limits from an individual producer datasheet or an unofficial composition table.
| Characteristic | Why the designation is insufficient | Recommended basis |
|---|---|---|
| Yield and tensile strength | EN 10106 does not define a universal mechanical-property set for M270-35A | Supplier-specific guarantee or an appropriate mechanically specified electrical-steel grade |
| Hardness and punchability | Producer, coating, processing route and lot can affect tool wear and edge quality | Agreed range, trial punching and tool-life criteria |
| Electrical resistivity | Not a grade requirement and producer values vary | Certified or agreed product data |
| High-frequency loss | The defining guarantee is at 50 Hz | Loss maps or coefficients at the actual frequency, polarization and waveform |
| Rotational loss | Epstein testing is alternating and one-dimensional | Rotational-loss data or machine-level validation |
| Coating resistance and weldability | The grade may be supplied uncoated or with different insulation systems | Specified coating class and agreed functional tests |
| Mechanical fatigue or rotor-burst capability | Not addressed by the magnetic grade designation | Application-specific mechanical testing and design allowables |
Published mechanical and physical values from a steelmaker describe that producer's product, not every material certified as M270-35A.
Supply condition, coating and purchasing
Strip is supplied in coils and sheet in bundles. The material may be uncoated or insulation-coated on one or both sides. Under EN 10106, the coating type, thickness, properties, stacking implications and verification are matters for agreement. EN 10342:2025 classifies electrical-steel surface insulations, but the coating classification by itself does not establish a numerical surface-insulation resistance; required functional values must be stated in the order.
| Item | What should be stated |
|---|---|
| Product specification | EN 10106:2015 and grade M270-35A / 1.0801 |
| Product form | Strip in coil or cut sheet |
| Dimensions | Nominal thickness, width and sheet length where applicable; required tolerance class or restrictions |
| Coil logistics | Internal diameter, maximum outside diameter, maximum mass and coil-axis orientation |
| Surface insulation | Uncoated or coating class; one- or two-sided; required thickness, resistance, thermal class, adhesion, weldability and annealing compatibility |
| Magnetic verification | Required inspection document, test method and any additional agreed loss points or directional testing |
| Mechanical data | Any required tensile, yield, elongation or hardness limits |
| Geometrical quality | Requirements for edge wave, residual curvature, camber, internal stress and burr control |
| Coil discontinuities | Whether welds or interleaves are permitted and whether they must be marked |
| Traceability | Heat or coil identification, inspection document type and marking requirements |
A purchase order containing only “M270-35A” leaves important coating, dimensional, packaging, certification and application-specific performance matters unresolved.
Processing into laminations and cores
Fully processed means that the steelmaker has developed the final magnetic properties by mill annealing; routine final-property annealing by the user is not required. If a post-punch stress-relief anneal is contemplated, its temperature, atmosphere and cycle must be agreed with the supplier, and the selected insulation coating must be compatible with that treatment.
Punching and shearing introduce plastic deformation, work hardening and residual stress near cut edges. These effects can reduce permeability and increase loss, particularly in narrow teeth, small components and geometries with a high cut-edge-to-volume ratio. Tool clearance, edge sharpness and wear therefore affect magnetic performance as well as burr height and dimensional quality. Laser cutting can introduce a thermally affected zone and should not automatically be assumed magnetically equivalent to production punching.
Stack joining can introduce further degradation. Welding, interlocking, riveting, clamping and shrink fitting may generate stress or create conductive bridges between laminations. Burr contact and damaged coating can permit interlaminar currents. Prototype and production validation should therefore use the intended cutting, stacking, joining and housing processes rather than relying only on mill-strip Epstein data.
The minimum of two reverse bends is a standardized technological ductility check. It is not a general forming limit and does not establish suitability for severe bending, drawing or structural loading.
Application and design implications
The combination of 0.35 mm gauge and a 2.70 W/kg power-frequency loss ceiling makes M270-35A suitable for efficient laminated magnetic circuits, particularly rotating-machine stators and rotors and other components in which flux changes direction within the sheet plane. The material remains anisotropic: the permitted loss anisotropy is ±17%, so rolling direction and lamination layout can still influence measured and assembled-core performance.
For inverter-fed or high-speed machines, the 50 Hz grade point is inadequate as a complete design model. Harmonics, high fundamental frequency, rotational flux, compressive assembly stress, temperature and cutting degradation can materially change loss and permeability. Electromagnetic analysis should use supplier-specific loss and magnetization data covering the operating range, followed by testing of representative processed laminations or complete cores.
| Grade | Maximum loss at 1.5 T, 50 Hz | Minimum J at 2,500 / 5,000 / 10,000 A/m | Practical relationship |
|---|---|---|---|
| M250-35A / 1.0800 | 2.50 W/kg | 1.49 / 1.60 / 1.70 T | Lower standardized loss ceiling; not automatically identical in strength, coating or high-frequency behavior |
| M270-35A / 1.0801 | 2.70 W/kg | 1.49 / 1.60 / 1.70 T | Reference grade |
| M300-35A / 1.0803 | 3.00 W/kg | 1.49 / 1.60 / 1.70 T | Higher standardized loss ceiling; may offer different commercial or processing characteristics |
Grades should be compared using the complete product specification and supplier data, not the loss number alone.
Inspection and acceptance priorities
| Stage | Priority checks |
|---|---|
| Incoming material | Grade and standard, coil identity, thickness, width, coating designation, inspection certificate and agreed magnetic results |
| Slitting or blanking | Edge condition, burr, camber, residual stress, coating damage and dimensional consistency |
| Core assembly | Stack height and mass, effective stacking factor, interlaminar shorting, weld or interlock effects and clamping stress |
| Qualification testing | Core loss and excitation under representative waveform, frequency, polarization, temperature and assembly condition |
| Substitution review | Standard edition, thickness, loss test point, polarization minima, coating, mechanical properties, processing route and certification |
Acceptance of the incoming coil to EN 10106 confirms compliance of the supplied flat product. It does not by itself demonstrate that the finished magnetic component will meet its efficiency, temperature-rise, noise or mechanical requirements.
Sources
- BS EN 10106:2015 — Cold rolled non-oriented electrical steel strip and sheet delivered in the fully processed stateBritish Standards Institution
- EN 10106:2015 standard previewCEN / Slovenian Institute for Standardization
- IEC 60404-8-4:2022+A1:2026 — Cold-rolled non-oriented electrical steel delivered in the fully-processed stateInternational Electrotechnical Commission
- IEC 60404-8-4:2022 standard previewInternational Electrotechnical Commission
- IEC 60404-2 — Epstein-frame measurement of electrical steelInternational Electrotechnical Commission
- BS EN 10342:2025 — Classification of surface insulations of electrical steelBritish Standards Institution
- BS EN 10251:2024 — Methods for geometrical characteristics of electrical steelBritish Standards Institution
- SIWATT M270-35A technical data sheetSIJ Acroni
- Influence of the cutting process on the magnetic properties of non-oriented electrical steelsJournal of Magnetism and Magnetic Materials
- ASTM A677-16(2023) — Nonoriented electrical steel fully processed typesASTM International
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