Steel 35W300-SRA (750–800 °C)
Heat-treated state
EN 35W300
Choose for small stamped cores where punching stress and burrs dominate: annealing at about 750–800 °C in protective atmosphere recovers 5–15% of the core-loss penalty, but strength drops to 270 MPa yield.
Values for the SRA condition
What is 35W300-SRA?
35W300-SRA is 35W300 heat treated to SRA — choose for small stamped cores where punching stress and burrs dominate: annealing at about 750–800 °C in protective atmosphere recovers 5–15% of the core-loss penalty, but strength drops to 270 MPa yield. 35W300-SRA has a yield strength of 270 MPa (39.2 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 91% of steel grades. Elongation at break is 30% and the elastic modulus is 200 GPa (29 Msi). 35W300-SRA has a density of 7.65 g/cm³ (0.276 lb/in³), lighter than 97% of steel grades. It melts at 1,480°C (2,696 °F).
Advantages
- Ductile — tolerates forming and impact — 30%, better than 93% of steel grades
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Low strength — 270 MPa (39.2 ksi), worse than 91% of steel grades
- Poor heat conductor — 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 88% of steel grades
- Low electrical conductivity — 3.6 % IACS, worse than 85% of steel grades
- Hard to polish — 45/100, worse than 84% of steel grades
35W300-SRA properties
Typical room-temperature values for 35W300-SRA; 5 are specific to this condition. Other listed values are 35W300 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
35W300-SRA has a density of 7.65 g/cm³ (0.276 lb/in³), lighter than 97% of steel grades. It melts at 1,480°C (2,696 °F).
Mechanical11
35W300-SRA has a yield strength of 270 MPa (39.2 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 91% of steel grades. Elongation at break is 30% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
35W300-SRA is rated for continuous service to 200°C (392 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 88% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
35W300-SRA conducts electricity at 3.6 % IACS, worse than 85% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of 35W300-SRA takes about 32 MJ of energy and emits 2.5 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 25%.
Manufacturability6
35W300-SRA's machinability is fair (42/100, worse than 73% of steel grades); weldability fair (45/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 35W300-SRA
Is 35W300 easy to machine?
Process mainly by precision blanking or laser cutting. The silicon content wears dies quickly, so use carbide or coated punches and hold burr height to 20 µm or less to prevent interlaminar shorting.
Can 35W300 be welded?
TIG or laser welding around the stack outside diameter is possible, but grain growth and residual stress in the heat-affected zone clearly raise local core loss; prefer interlock tabs, bonding or shrink rings instead.
Can 35W300 be formed, bent or molded?
Blanking behaviour is good; keep bend radii at 1.5t or greater. Not suitable for deep drawing. A 750–800 °C stress-relief anneal in a protective atmosphere can be applied after stamping, provided the coating is a heat-resistant type.
What surface finishes work on 35W300?
Coated material is used as supplied and needs no further treatment. Bare stock must be painted or oxide-treated against rust, and coating must be removed locally before welding or brazing.
35W300 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 |
|---|---|---|
| SiSi+Al total approx. 3.2-3.6%; sets resistivity and core loss | 2.4 – 3.2 | 2.9 |
| Al | 0.2 – 0.8 | 0.5 |
| Mn | 0.1 – 0.5 | 0.3 |
| Clow C in finished product prevents magnetic aging | ≤ 0.01 | 0 |
| S | ≤ 0.01 | 0 |
| P | ≤ 0.05 | 0.02 |
| N | ≤ 0 | 0 |
| Fe | balance |
35W300-SRA — frequently asked
What is 35W300-SRA used for?
35W300-SRA is typically used for industrial motor laminations, generators and medium transformers. In short: thin-gauge non-oriented steel; M19-class core loss; good punchability.
What is the yield strength of 35W300-SRA?
35W300-SRA has a typical yield strength of 270 MPa (39.2 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 91% of steel grades.
Is 35W300-SRA easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Process mainly by precision blanking or laser cutting. The silicon content wears dies quickly, so use carbide or coated punches and hold burr height to 20 µm or less to prevent interlaminar shorting.
Can 35W300-SRA be welded?
With care — weldability is rated fair (45/100). TIG or laser welding around the stack outside diameter is possible, but grain growth and residual stress in the heat-affected zone clearly raise local core loss; prefer interlock tabs, bonding or shrink rings instead.
What surface finishes work on 35W300-SRA?
Coated material is used as supplied and needs no further treatment. Bare stock must be painted or oxide-treated against rust, and coating must be removed locally before welding or brazing.
Can 35W300-SRA be formed, bent or molded?
Blanking behaviour is good; keep bend radii at 1.5t or greater. Not suitable for deep drawing. A 750–800 °C stress-relief anneal in a protective atmosphere can be applied after stamping, provided the coating is a heat-resistant type.
What is the maximum service temperature of 35W300-SRA?
35W300-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
- ASTM A677 Nonoriented Electrical Steel Fully Processed Types — ASTM (2020)
- 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.