Steel M400-50A-SRA
Heat-treated state
SRA = stress-relief annealed after blanking
Pick when punching/laser-cut edge stresses must be removed to recover the guaranteed core loss and permeability; strength and hardness drop.
Values for the SRA condition
What is M400-50A-SRA?
M400-50A-SRA is M400-50A heat treated to SRA — pick when punching/laser-cut edge stresses must be removed to recover the guaranteed core loss and permeability; strength and hardness drop. M400-50A-SRA has a yield strength of 280 MPa (40.6 ksi) and a tensile strength of 410 MPa (59.5 ksi) — weaker than 90% of steel grades. Elongation at break is 32% and the elastic modulus is 200 GPa (29 Msi). M400-50A-SRA has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 95% of steel grades. It melts at 1,480°C (2,696 °F).
Advantages
- Ductile — tolerates forming and impact — 32%, better than 95% of steel grades
- Forms and bends easily — 75/100, better than 90% of steel grades
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Low strength — 280 MPa (40.6 ksi), worse than 90% of steel grades
- Poor heat conductor — 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades
- Hard to polish — 45/100, worse than 84% of steel grades
- Low electrical conductivity — 4.1 % IACS, worse than 83% of steel grades
M400-50A-SRA properties
Typical room-temperature values for M400-50A-SRA; 7 are specific to this condition. Other listed values are M400-50A reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
M400-50A-SRA has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 95% of steel grades. It melts at 1,480°C (2,696 °F).
Mechanical12
M400-50A-SRA has a yield strength of 280 MPa (40.6 ksi) and a tensile strength of 410 MPa (59.5 ksi) — weaker than 90% of steel grades. Elongation at break is 32% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
M400-50A-SRA is rated for continuous service to 200°C (392 °F). It conducts heat at 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
M400-50A-SRA conducts electricity at 4.1 % IACS, worse than 83% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of M400-50A-SRA takes about 33 MJ of energy and emits 2.4 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 25%.
Manufacturability7
M400-50A-SRA's machinability is fair (50/100, worse than 53% of steel grades); weldability fair (40/100); formability very good (75/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with M400-50A-SRA
Is M400-50A easy to machine?
Almost always blanked/punched or laser-/wire-cut rather than machined; keep dies sharp (clearance ≈5 % of thickness) because burrs and edge work-hardening raise core loss.
Can M400-50A be welded?
TIG/laser tack welding of stacks is possible but the HAZ short-circuits laminations and degrades loss — prefer interlocking, cleating or bonding varnish.
Can M400-50A be formed, bent or molded?
Good punchability and moderate bendability; avoid heavy cold work near the tooth roots, and stress-relief anneal at 750–800 °C in a protective atmosphere if magnetic performance is critical.
What surface finishes work on M400-50A?
Supplied with mill-applied EC-3/EC-5/EC-6 insulation; bare edges should be varnish-impregnated or oiled since the base steel rusts quickly in humid air.
M400-50A 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 |
|---|---|---|
| Cdecarburised in final anneal | ≤ 0.01 | 0 |
| SiSi+Al ≈ 2.6–3.0 % sets resistivity | 1.8 – 3 | 2.4 |
| Al | 0.15 – 0.6 | 0.35 |
| Mn | 0.1 – 0.5 | 0.3 |
| Psometimes added for strength | ≤ 0.06 | 0.02 |
| S | ≤ 0.01 | 0 |
| N | ≤ 0.01 | 0 |
| Fe | balance |
M400-50A-SRA — frequently asked
What is M400-50A-SRA used for?
M400-50A-SRA is typically used for motor laminations, small transformers and generators. In short: mainstream EU motor lamination; near-isotropic magnetic properties; good punchability.
What is the yield strength of M400-50A-SRA?
M400-50A-SRA has a typical yield strength of 280 MPa (40.6 ksi) and a tensile strength of 410 MPa (59.5 ksi) — weaker than 90% of steel grades.
Is M400-50A-SRA easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Almost always blanked/punched or laser-/wire-cut rather than machined; keep dies sharp (clearance ≈5 % of thickness) because burrs and edge work-hardening raise core loss.
Can M400-50A-SRA be welded?
With care — weldability is rated fair (40/100). TIG/laser tack welding of stacks is possible but the HAZ short-circuits laminations and degrades loss — prefer interlocking, cleating or bonding varnish.
What surface finishes work on M400-50A-SRA?
Supplied with mill-applied EC-3/EC-5/EC-6 insulation; bare edges should be varnish-impregnated or oiled since the base steel rusts quickly in humid air.
Can M400-50A-SRA be formed, bent or molded?
Good punchability and moderate bendability; avoid heavy cold work near the tooth roots, and stress-relief anneal at 750–800 °C in a protective atmosphere if magnetic performance is critical.
What is the maximum service temperature of M400-50A-SRA?
M400-50A-SRA 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.
Sources
- EN 10106 — Cold rolled non-oriented electrical steel strip and sheet delivered in the fully processed state — CEN (2015)
- EN 10342 — Magnetic materials: classification of surface insulations of electrical steel — CEN (2005)
- Non-oriented electrical steel product data (M400-50A / 50W400 grades) — European & Chinese electrical steel producers (2023)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (magnetically soft materials) — ASM International (1990)
- (SMM / Mysteel) (2025)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.