Steel 35W250-SRA
Heat-treated state
EN 35W250
SRA = stress-relief annealed after punching
Apply after punching or shearing (typically 750–800 °C, protective atmosphere) to relieve cut-edge stress and recover 5–15% of core loss; hardness and strength drop and the coating must tolerate the cycle.
Values for the SRA condition
Other 35W250 tempers and conditions
35W250 is listed in 2 conditions; see the grade overview at 35W250.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SRAThis page Stress-relief annealed after punching | Apply after punching or shearing (typically 750–800 °C, protective atmosphere) to relieve cut-edge stress and recover 5–15% of core loss; hardness and strength drop and the coating must tolerate the cycle. | 320 | 450 | 16 | 166 HB | 3.1 % IACS |
Final AnnealedDefault fully processed, insulation coated (as supplied) | Standard as-supplied state: mill decarburised, recrystallisation annealed and insulation coated, so laminations stack directly after punching, with core loss P1.5/50 of 2.50 W/kg or less. | 360 | 480 | 12 | 180 HB | 3.1 % IACS |
What is 35W250-SRA?
35W250-SRA is 35W250 heat treated to SRA — apply after punching or shearing (typically 750–800 °C, protective atmosphere) to relieve cut-edge stress and recover 5–15% of core loss; hardness and strength drop and the coating must tolerate the cycle. 35W250-SRA has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 81% of steel grades. Elongation at break is 16% and the elastic modulus is 195 GPa (28.3 Msi). 35W250-SRA has a density of 7.65 g/cm³ (0.276 lb/in³), lighter than 97% of steel grades. It melts at 1,490°C (2,714 °F). Final Annealed is the default condition FabDigit quotes; SRA is available on request or by drawing note.
Limitations
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Hard to polish — 40/100, worse than 96% of steel grades
- Low electrical conductivity — 3.1 % IACS, worse than 89% of steel grades
- Poor heat conductor — 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 88% of steel grades
- Low strength — 320 MPa (46.4 ksi), worse than 81% of steel grades
35W250-SRA properties
Typical room-temperature values for 35W250-SRA; 21 are specific to this condition. Other listed values are 35W250 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
35W250-SRA has a density of 7.65 g/cm³ (0.276 lb/in³), lighter than 97% of steel grades. It melts at 1,490°C (2,714 °F).
Mechanical14
35W250-SRA has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 81% of steel grades. Elongation at break is 16% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
35W250-SRA is rated for continuous service to 180°C (356 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 88% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
35W250-SRA conducts electricity at 3.1 % IACS, worse than 89% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of 35W250-SRA takes about 32 MJ of energy and emits 2.4 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 15%.
Manufacturability7
35W250-SRA's machinability is fair (48/100, worse than 57% of steel grades); weldability fair (35/100); formability fair (50/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 35W250-SRA
Is 35W250 easy to machine?
Process by precision blanking or laser cutting; the high silicon content and the coating are abrasive, so use carbide punch tooling and regrind often to keep burr height ≤5 % of strip thickness. Conventional chip machining is uneconomic.
Can 35W250 be welded?
Avoid welding: it short-circuits laminations, and HAZ grain growth and residual stress raise core loss. Where a stack must be fixed, use short tack or laser spot welds and accept the loss in magnetic performance.
Can 35W250 be formed, bent or molded?
Suitable only for flat blanking and shallow bends; keep the bend radius ≥1.5t and bend along the rolling direction. Cold bendability of 3 % Si material is poor — no deep drawing or large deformation.
What surface finishes work on 35W250?
Supplied with an inorganic or semi-organic insulating coating (C-3/C-5/C-6 types); do not abrade before stacking. If stress-relief annealing is needed after blanking, run it in a protective atmosphere and confirm the coating temperature rating.
35W250 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 |
|---|---|---|
| CGB/T 2521 grade by magnetic loss; typical high-grade non-oriented | ≤ 0.01 | 0 |
| Si | 2.6 – 3.4 | 3 |
| AlSi+Al raise resistivity and lower eddy-current loss | 0.3 – 1 | 0.6 |
| Mn | 0.1 – 0.5 | 0.25 |
| P | ≤ 0.05 | 0.02 |
| S | ≤ 0.01 | 0 |
| N | ≤ 0 | 0 |
| Fe | balance | — |
35W250-SRA — frequently asked
What is 35W250-SRA used for?
35W250-SRA is typically used for traction motor laminations, high-efficiency industrial motor cores, inverter compressor motor stators, generator stator and rotor laminations, medium- and high-frequency core stacks and small transformer cores. In short: workhorse electrical-steel coil.
What is the yield strength of 35W250-SRA?
35W250-SRA has a typical yield strength of 320 MPa (46.4 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 81% of steel grades. Strength varies by condition: see the 2 listed tempers.
Is 35W250-SRA easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 57% of steel grades). Process by precision blanking or laser cutting; the high silicon content and the coating are abrasive, so use carbide punch tooling and regrind often to keep burr height ≤5 % of strip thickness. Conventional chip machining is uneconomic.
Can 35W250-SRA be welded?
With care — weldability is rated fair (35/100). Avoid welding: it short-circuits laminations, and HAZ grain growth and residual stress raise core loss. Where a stack must be fixed, use short tack or laser spot welds and accept the loss in magnetic performance.
What surface finishes work on 35W250-SRA?
Supplied with an inorganic or semi-organic insulating coating (C-3/C-5/C-6 types); do not abrade before stacking. If stress-relief annealing is needed after blanking, run it in a protective atmosphere and confirm the coating temperature rating.
Can 35W250-SRA be formed, bent or molded?
Suitable only for flat blanking and shallow bends; keep the bend radius ≥1.5t and bend along the rolling direction. Cold bendability of 3 % Si material is poor — no deep drawing or large deformation.
What is the maximum service temperature of 35W250-SRA?
35W250-SRA is rated for continuous use to about 180°C (356 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 35W250 Final Annealed and 35W250-SRA?
Final Annealed is the default condition — standard as-supplied state: mill decarburised, recrystallisation annealed and insulation coated, so laminations stack directly after punching, with core loss P1.5/50 of 2.50 W/kg or less. SRA: apply after punching or shearing (typically 750–800 °C, protective atmosphere) to relieve cut-edge stress and recover 5–15% of core loss; hardness and strength drop and the coating must tolerate the cycle. Yield strength is 360 MPa in Final Annealed versus 320 MPa in SRA.
Can FabDigit make parts in 35W250-SRA?
Yes — 35W250-SRA is available for sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- IEC 60404-8-4 Specification for cold-rolled non-oriented electrical steel strip and sheet — IEC (2013)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (soft magnetic 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.