Steel E3404-SRA
Heat-treated state
GOST E3404 (Э3404)
SRA = stress-relief annealed after shearing/slitting
Use after cutting, bending or wound-core forming to recover the core loss lost to mechanical stress.
Values for the SRA condition
What is E3404-SRA?
E3404-SRA is E3404 heat treated to SRA — use after cutting, bending or wound-core forming to recover the core loss lost to mechanical stress. E3404-SRA has a yield strength of 295 MPa (42.8 ksi) and a tensile strength of 335 MPa (48.6 ksi) — weaker than 87% of steel grades. Elongation at break is 13% and the elastic modulus is 115 GPa (16.7 Msi). E3404-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).
Limitations
- Low stiffness — 115 GPa (16.7 Msi), worse than 100% of steel grades
- Hard to polish — 40/100, worse than 96% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Poor heat conductor — 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades
- Low strength — 295 MPa (42.8 ksi), worse than 87% of steel grades
E3404-SRA properties
Typical room-temperature values for E3404-SRA; 6 are specific to this condition. Other listed values are E3404 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
E3404-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).
Mechanical12
E3404-SRA has a yield strength of 295 MPa (42.8 ksi) and a tensile strength of 335 MPa (48.6 ksi) — weaker than 87% of steel grades. Elongation at break is 13% and the elastic modulus is 115 GPa (16.7 Msi).
Thermal6
E3404-SRA is rated for continuous service to 200°C (392 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
E3404-SRA conducts electricity at 3.6 % IACS, worse than 85% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of E3404-SRA takes about 34 MJ of energy and emits 2.4 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 15%.
Manufacturability7
E3404-SRA's machinability is fair (35/100, worse than 84% of steel grades); weldability poor (30/100); formability fair (40/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with E3404-SRA
Is E3404 easy to machine?
Blank by precision punching or laser/EDM only where loss penalty is acceptable; carbide or coated tooling is required because the ceramic coating is highly abrasive and burrs shortcut laminations.
Can E3404 be welded?
TIG/laser tack welding of stack edges is possible but the HAZ loses its Goss texture and coating, raising local loss — avoid welds crossing the flux path.
Can E3404 be formed, bent or molded?
Limited to slitting, shearing and gentle wound-core bending; the strip is notch-sensitive and any plastic strain must be removed by an 800 °C stress-relief anneal.
What surface finishes work on E3404?
Supplied with a forsterite (glass film) plus phosphate insulating top coat; do not shot-blast or pickle, touch up cut edges with core-plate varnish before oil immersion.
E3404 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 |
|---|---|---|
| Siraises resistivity, lowers eddy-current loss | 2.8 – 3.4 | 3.1 |
| Cafter decarburizing anneal | ≤ 0.01 | 0 |
| Mnwith S forms MnS inhibitor | 0.05 – 0.25 | 0.12 |
| Sinhibitor former, residual kept low | ≤ 0.01 | 0.01 |
| P | ≤ 0.03 | 0.01 |
| AlAlN inhibitor in HiB route | 0.01 – 0.04 | 0.03 |
| N | ≤ 0.01 | 0.01 |
| Cu | ≤ 0.3 | 0.1 |
| Fe | balance | — |
E3404-SRA — frequently asked
What is E3404-SRA used for?
E3404-SRA is typically used for transformer cores, reactor cores, distribution transformer laminations, wound (toroidal) cores, instrument transformer cores and welding transformer cores. In short: GOST grain-oriented grade; multiple lamination gauges stocked; notch-sensitive, low formability.
What is the yield strength of E3404-SRA?
E3404-SRA has a typical yield strength of 295 MPa (42.8 ksi) and a tensile strength of 335 MPa (48.6 ksi) — weaker than 87% of steel grades.
Is E3404-SRA easy to machine?
Not especially — machinability is rated fair (35/100, worse than 84% of steel grades). Blank by precision punching or laser/EDM only where loss penalty is acceptable; carbide or coated tooling is required because the ceramic coating is highly abrasive and burrs shortcut laminations.
Can E3404-SRA be welded?
Not readily — weldability is rated poor (30/100). TIG/laser tack welding of stack edges is possible but the HAZ loses its Goss texture and coating, raising local loss — avoid welds crossing the flux path.
What surface finishes work on E3404-SRA?
Supplied with a forsterite (glass film) plus phosphate insulating top coat; do not shot-blast or pickle, touch up cut edges with core-plate varnish before oil immersion.
Can E3404-SRA be formed, bent or molded?
Limited to slitting, shearing and gentle wound-core bending; the strip is notch-sensitive and any plastic strain must be removed by an 800 °C stress-relief anneal.
What is the maximum service temperature of E3404-SRA?
E3404-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
- ГОСТ 21427.1-83 — Сталь электротехническая холоднокатаная анизотропная тонколистовая — Gosstandart (1983)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (magnetically soft materials) — ASM International (1990)
- Grain-oriented electrical steel strip datasheets (CGO/HiB grades) — Baosteel / NLMK VIZ-Stal (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.