Steel M15
AISI/SAE M15 · UNS T11315
M15 is a non-oriented electrical steel (ASTM A677 M15, also listed as 50W400 and T11315) with higher silicon than M19, giving lower core loss where improved efficiency justifies the added cost.
Reference datasheet — M15 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
M15 tempers and conditions
M15 is supplied in 2 conditions, soft to hard.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Semi-processed after customer quality anneal | Condition of finished laminations after the user's decarburizing/grain-growth anneal; softest state, lowest core loss. | 295 | 430 | 25 | 140 HB | 3.4 % IACS |
Semi-processed, as-shipped | Choose when the laminator will stress-relief/quality anneal punched parts to develop grain size and final core loss. | 400 | 510 | 9 | 185 HB | 3.3 % IACS |
Supply forms, finishes and certifications
Ways M15 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
C-3 | Organic (enamel/varnish) surface insulation | Surface finish |
C-5 | Inorganic/ceramic-filled organic core-plate, anneal-resistant | Surface finish |
FPDefault | Fully processed, decarburized/annealed, C-5 core-plate coated | Surface finish |
FP-0.35 | FP 0.35 mm | Supply option |
FP-0.50 | FP 0.50 mm | Supply option |
FP-0.64 | FP 0.64 mm | Supply option |
What is M15?
M15 is a non-oriented electrical steel (ASTM A677 M15, also listed as 50W400 and T11315) with higher silicon than M19, giving lower core loss where improved efficiency justifies the added cost. It is stocked fully processed in 0.35, 0.50 and 0.64 mm thicknesses with C-3 or C-5 core-plate insulation, plus semi-processed material for annealing after punching. Typical mechanical values are 340 MPa yield, 470 MPa tensile, 15 % elongation and 82 HRB, with service to 200 °C. The silicon content makes the sheet abrasive to punch and limits tight bending; M19 is the lower-cost alternative. M15 has a density of 7.65 g/cm³ (0.276 lb/in³), lighter than 97% of steel grades. It melts at 1,500°C (2,732 °F). M15 has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 76% of steel grades. Elongation at break is 15% and the elastic modulus is 200 GPa (29 Msi).
What is M15 used for?
- high-efficiency motors
- generators
- small transformers
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Poor heat conductor — 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades
- Low electrical conductivity — 3.4 % IACS, worse than 86% of steel grades
- Low strength — 340 MPa (49.3 ksi), worse than 76% of steel grades
M15 properties
Typical room-temperature values; bars are the position among steel grades.
Physical3
M15 has a density of 7.65 g/cm³ (0.276 lb/in³), lighter than 97% of steel grades. It melts at 1,500°C (2,732 °F).
Mechanical12
M15 has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 76% of steel grades. Elongation at break is 15% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
M15 is rated for continuous service to 200°C (392 °F). It conducts heat at 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
M15 conducts electricity at 3.4 % IACS, worse than 86% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of M15 takes about 34 MJ of energy and emits 2.4 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
M15's machinability is fair (45/100, worse than 65% of steel grades); weldability fair (50/100); formability good (55/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. M15 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with M15
Is M15 easy to machine?
Rarely machined; silicon makes it abrasive and gummy — use carbide tooling, and grind/EDM only with a follow-up stress-relief anneal to restore magnetics.
Can M15 be welded?
Lamination stacks are TIG/laser welded only in short skip beads — weld metal shorts laminations and locally destroys permeability; prefer interlocking or bonding.
Can M15 be formed, bent or molded?
Punches cleanly with sharp (<25 µm burr) dies and tight clearance (~5 % of thickness); limited bendability, avoid tight radii transverse to rolling direction.
M15 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Cfully processed, decarburized | ≤ 0.01 | 0 |
| Simain resistivity former | 2.7 – 3.3 | 3 |
| AlSi+Al total ≈3.3–3.6 % | 0.2 – 0.9 | 0.5 |
| Mn | 0.1 – 0.45 | 0.25 |
| P | ≤ 0.05 | 0.02 |
| Skept low for grain growth | ≤ 0.01 | 0 |
| N | ≤ 0 | 0 |
| Fe | balance |
What surface finishes work on M15?
Supplied pre-insulated with C-3 or C-5 core-plate; bare edges rust, so varnish-impregnate or encapsulate finished stacks and avoid pickling that removes the coating.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel M15 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T11315
- Similar grades
- 50W400
How much does M15 cost?
M15 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
M15 — frequently asked
What is M15 used for?
M15 is typically used for high-efficiency motors, generators and small transformers. In short: lower core loss than M19; high-efficiency lamination grade; pre-insulated core-plate stock.
What is the yield strength of M15?
M15 has a typical yield strength of 340 MPa (49.3 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 76% of steel grades. Strength varies by condition: see the 2 listed tempers.
Is M15 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Rarely machined; silicon makes it abrasive and gummy — use carbide tooling, and grind/EDM only with a follow-up stress-relief anneal to restore magnetics.
Can M15 be welded?
With care — weldability is rated fair (50/100). Lamination stacks are TIG/laser welded only in short skip beads — weld metal shorts laminations and locally destroys permeability; prefer interlocking or bonding.
What surface finishes work on M15?
Supplied pre-insulated with C-3 or C-5 core-plate; bare edges rust, so varnish-impregnate or encapsulate finished stacks and avoid pickling that removes the coating.
Can M15 be formed, bent or molded?
Punches cleanly with sharp (<25 µm burr) dies and tight clearance (~5 % of thickness); limited bendability, avoid tight radii transverse to rolling direction.
What is the maximum service temperature of M15?
M15 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does M15 cost?
M15 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM A677 – Nonoriented Electrical Steel Fully Processed Types — ASTM International (2020)
- ASTM A683 – Nonoriented Electrical Steel, Semiprocessed Types — ASTM International (2019)
- Non-oriented electrical steel product data (M-grades, C-5 coating) — Cleveland-Cliffs / AK Steel (2021)
- ASM Handbook Vol. 1 – Properties of Magnetically Soft Materials — ASM International (1990)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.