Steel Silicon Steel-SRA
Heat-treated state
SRA = stress-relief annealed after stamping/slitting
Apply after punching, bending or slitting to recover permeability and remove the loss penalty from cut edges and burrs.
Values for the SRA condition
Other Silicon Steel tempers and conditions
Silicon Steel is listed in 8 conditions; see the grade overview at Silicon Steel.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SRAThis page Stress-relief annealed after stamping/slitting | Apply after punching, bending or slitting to recover permeability and remove the loss penalty from cut edges and burrs. | 300 | 440 | 25 | 157 HB | 3.4 % IACS |
high-permeability grain-oriented (optionally laser-scribed) | Premium transformer grade: sharper Goss texture plus tensile coating/laser scribing for the lowest core loss at high induction. | 315 | 370 | 7 | 10 HRC | 3.6 % IACS |
AnnealedDefault fully processed, decarburized and final-annealed strip | Default stocked condition: magnetic properties already developed, ready to punch and stack without further annealing. | 320 | 460 | 20 | 170 HB | — |
Cold-rolled grain-oriented (Goss texture), fully processed | Use for transformer and reactor cores where flux runs along the rolling direction; lowest loss but strongly anisotropic. | 320 | 380 | 8 | 10 HRC | 3.6 % IACS |
Cold-rolled non-oriented, fully processed with core-plate coating | Standard motor/generator lamination material: isotropic in-plane magnetics, coated for interlaminar insulation. | 330 | 470 | 20 | 9 HRC | 3.4 % IACS |
hot-rolled silicon steel sheet/band | Legacy/low-cost option for thick laminations, small transformers and pole pieces where loss targets are loose. | 330 | 500 | 22 | 160 HB | 5.7 % IACS |
supplied hard-ish, customer anneals after stamping | Pick for high-volume motor laminations where the stamper runs its own decarburize/grain-growth anneal to hit final loss values. | 360 | 490 | 16 | 11 HRC | 4.9 % IACS |
as-cold-rolled (un-annealed, work-hardened) strip | Choose when high stiffness/strength and tight thickness tolerance matter and the part will be annealed later, or for non-magnetic structural use of the strip. | 580 | 650 | 5 | 20 HRC | 3.4 % IACS |
What is Silicon Steel-SRA?
Silicon Steel-SRA is Silicon Steel heat treated to SRA — apply after punching, bending or slitting to recover permeability and remove the loss penalty from cut edges and burrs. Silicon Steel-SRA has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 440 MPa (63.8 ksi) — weaker than 86% of steel grades. Elongation at break is 25% and the elastic modulus is 200 GPa (29 Msi). Silicon Steel-SRA 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). Annealed is the default condition FabDigit quotes; SRA is available on request or by drawing note.
Advantages
- Forms and bends easily — 65/100, better than 81% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Poor heat conductor — 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 88% of steel grades
- Low strength — 300 MPa (43.5 ksi), worse than 86% of steel grades
- Low electrical conductivity — 3.4 % IACS, worse than 86% of steel grades
- Difficult to machine — 40/100, worse than 77% of steel grades
Silicon Steel-SRA properties
Typical room-temperature values for Silicon Steel-SRA; 23 are specific to this condition. Other listed values are Silicon Steel reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
Silicon Steel-SRA 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
Silicon Steel-SRA has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 440 MPa (63.8 ksi) — weaker than 86% of steel grades. Elongation at break is 25% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
Silicon Steel-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 12 µm/m·K (6.67 µin/in·°F).
Electrical3
Silicon Steel-SRA conducts electricity at 3.4 % IACS, worse than 86% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of Silicon Steel-SRA takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
Silicon Steel-SRA's machinability is fair (40/100, worse than 77% of steel grades); weldability fair (48/100); formability good (65/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Silicon Steel-SRA
Is Silicon Steel easy to machine?
Silicon makes chips abrasive and burr-prone — use sharp carbide or coated HSS, generous flood coolant, and expect fast tool wear; thin strip is normally punched or laser/EDM cut rather than machined.
Can Silicon Steel be welded?
Weldable by TIG/laser/resistance after stripping core-plate, but the HAZ grows coarse or oxidized and raises core loss — keep welds off the flux path or stress-relief anneal afterwards.
Can Silicon Steel be formed, bent or molded?
Fully processed strip stamps and bends well with sharp, well-maintained tooling (clearance ~5 % of thickness); high-Si and grain-oriented grades are notch-sensitive and crack on tight bends.
What surface finishes work on Silicon Steel?
Normally used as supplied with inorganic/organic core-plate (C-3/C-5/C-6) or phosphate insulation; bare edges need varnish, oil or paint since the steel rusts readily. Not anodizable.
Silicon Steel 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 |
|---|---|---|
| Si≈0.5–1.5 % low grades, 2.5–3.5 % high grades and all grain-oriented | 0.5 – 3.5 | 3 |
| Cdecarburized to <0.005 % in fully processed strip | 0 – 0.03 | 0 |
| Mn | 0.05 – 0.5 | 0.2 |
| Alresistivity/grain-growth control in NGO; AlN inhibitor in GO | 0.05 – 0.6 | 0.3 |
| P | ≤ 0.06 | 0.02 |
| SMnS inhibitor in conventional GO | ≤ 0.02 | 0.01 |
| N | ≤ 0.01 | 0 |
| Snoptional grain-boundary segregant in some GO grades | ≤ 0.1 | — |
| Fe | balance | — |
Silicon Steel-SRA — frequently asked
What is Silicon Steel-SRA used for?
Silicon Steel-SRA is typically used for transformer cores, electric motor stator and rotor laminations, generator and alternator cores, inductor and choke cores, current and instrument transformer cores and solenoid and relay armatures. In short: superior magnetic properties.
What is the yield strength of Silicon Steel-SRA?
Silicon Steel-SRA has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 440 MPa (63.8 ksi) — weaker than 86% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is Silicon Steel-SRA easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Silicon makes chips abrasive and burr-prone — use sharp carbide or coated HSS, generous flood coolant, and expect fast tool wear; thin strip is normally punched or laser/EDM cut rather than machined.
Can Silicon Steel-SRA be welded?
With care — weldability is rated fair (48/100). Weldable by TIG/laser/resistance after stripping core-plate, but the HAZ grows coarse or oxidized and raises core loss — keep welds off the flux path or stress-relief anneal afterwards.
What surface finishes work on Silicon Steel-SRA?
Normally used as supplied with inorganic/organic core-plate (C-3/C-5/C-6) or phosphate insulation; bare edges need varnish, oil or paint since the steel rusts readily. Not anodizable.
Can Silicon Steel-SRA be formed, bent or molded?
Fully processed strip stamps and bends well with sharp, well-maintained tooling (clearance ~5 % of thickness); high-Si and grain-oriented grades are notch-sensitive and crack on tight bends.
What is the maximum service temperature of Silicon Steel-SRA?
Silicon Steel-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.
What is the difference between Silicon Steel Annealed and Silicon Steel-SRA?
Annealed is the default condition — default stocked condition: magnetic properties already developed, ready to punch and stack without further annealing. SRA: apply after punching, bending or slitting to recover permeability and remove the loss penalty from cut edges and burrs. Yield strength is 320 MPa in Annealed versus 300 MPa in SRA.
Can FabDigit make parts in Silicon Steel-SRA?
Yes — Silicon Steel-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
- ASTM A677 — Nonoriented Electrical Steel Fully Processed Types — ASTM (2020)
- ASTM A683 — Nonoriented Electrical Steel Semiprocessed Types — ASTM (2019)
- ASTM A876 — Flat-Rolled, Grain-Oriented, Silicon-Iron, Fully Processed Types — ASTM (2019)
- IEC 60404-8-4 — Cold-rolled non-oriented electrical steel sheet and strip — IEC (2013)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels (Soft Magnetic Materials) — ASM International (1990)
- Selection of Electrical Steels for Magnetic Cores — AK Steel / Cleveland-Cliffs (2019)
- Electrical steel product catalogue (NGO / GO / Hi-B) — Baosteel (2023)
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.