Steel 50W470-SRA
Heat-treated state
EN 50W470 · ASTM A677 · JIS 50A470
SRA = stress-relief annealed after blanking
Choose when punching/laser-cutting residual stress must be removed to recover core loss (typically 5–15 % lower loss) in high-efficiency motor cores.
Values for the SRA condition
Other 50W470 tempers and conditions
50W470 is listed in 2 conditions; see the grade overview at 50W470.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SRAThis page Stress-relief annealed after blanking | Choose when punching/laser-cutting residual stress must be removed to recover core loss (typically 5–15 % lower loss) in high-efficiency motor cores. | 280 | 410 | 33 | 143 HB | 4.1 % IACS |
Final AnnealedDefault fully processed, insulation coated (as delivered) | Standard fully-processed coil/sheet as shipped: magnetic properties guaranteed, ready to punch and stack without further annealing. | 310 | 440 | 30 | 152 HB | 4.1 % IACS |
What is 50W470-SRA?
50W470-SRA is 50W470 heat treated to SRA — choose when punching/laser-cutting residual stress must be removed to recover core loss (typically 5–15 % lower loss) in high-efficiency motor cores. 50W470-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 33% and the elastic modulus is 190 GPa (27.6 Msi). 50W470-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). Final Annealed is the default condition FabDigit quotes; SRA is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 33%, better than 96% 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 — 28 W/m·K (16.2 BTU/hr·ft·°F), worse than 85% of steel grades
- Low electrical conductivity — 4.1 % IACS, worse than 83% of steel grades
50W470-SRA properties
Typical room-temperature values for 50W470-SRA; 19 are specific to this condition. Other listed values are 50W470 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
50W470-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
50W470-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 33% and the elastic modulus is 190 GPa (27.6 Msi).
Thermal5
50W470-SRA is rated for continuous service to 200°C (392 °F). It conducts heat at 28 W/m·K (16.2 BTU/hr·ft·°F), worse than 85% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
50W470-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 50W470-SRA takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 25%.
Manufacturability6
50W470-SRA's machinability is fair (48/100, worse than 57% of steel grades); weldability good (55/100); formability very good (75/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 50W470-SRA
Is 50W470 easy to machine?
Primarily blanked/punched or laser cut; the ~2 % Si makes it abrasive, so use carbide dies with tight clearance (≈5 % of thickness) and re-grind often to limit burr and edge stress.
Can 50W470 be welded?
Only tack/laser stitch welding of stacks is advisable — HAZ recrystallisation and burr shorting between laminations raise eddy-current loss.
Can 50W470 be formed, bent or molded?
Good flat-blanking and mild bending formability; avoid heavy drawing or cold work, and interleave die maintenance to keep burr height below ~20 µm.
What surface finishes work on 50W470?
Delivered with a thin inorganic/semi-organic insulating varnish (C-3/C-5 class); do not degrease aggressively, and if stress-relief annealing choose a coating rated for 750–800 °C.
50W470 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 specifies magnetic properties, not chemistry; values are typical mill analysis | ≤ 0.01 | 0 |
| Si | 1.8 – 2.5 | 2.2 |
| Al | 0.2 – 0.6 | 0.35 |
| Mn | 0.15 – 0.6 | 0.3 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.01 | 0 |
| N | ≤ 0.01 | 0 |
| Fe | balance | — |
50W470-SRA — frequently asked
What is 50W470-SRA used for?
50W470-SRA is typically used for motor stator and rotor laminations, traction and EV drive motor cores, generator and alternator stacks, distribution transformer cores, servo and stepper motor laminations and reactor and choke cores. In short: standard electrical-steel coil.
What is the yield strength of 50W470-SRA?
50W470-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. Strength varies by condition: see the 2 listed tempers.
Is 50W470-SRA easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 57% of steel grades). Primarily blanked/punched or laser cut; the ~2 % Si makes it abrasive, so use carbide dies with tight clearance (≈5 % of thickness) and re-grind often to limit burr and edge stress.
Can 50W470-SRA be welded?
Yes — weldability is rated good (55/100). Only tack/laser stitch welding of stacks is advisable — HAZ recrystallisation and burr shorting between laminations raise eddy-current loss.
What surface finishes work on 50W470-SRA?
Delivered with a thin inorganic/semi-organic insulating varnish (C-3/C-5 class); do not degrease aggressively, and if stress-relief annealing choose a coating rated for 750–800 °C.
Can 50W470-SRA be formed, bent or molded?
Good flat-blanking and mild bending formability; avoid heavy drawing or cold work, and interleave die maintenance to keep burr height below ~20 µm.
What is the maximum service temperature of 50W470-SRA?
50W470-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 50W470 Final Annealed and 50W470-SRA?
Final Annealed is the default condition — standard fully-processed coil/sheet as shipped: magnetic properties guaranteed, ready to punch and stack without further annealing. SRA: choose when punching/laser-cutting residual stress must be removed to recover core loss (typically 5–15 % lower loss) in high-efficiency motor cores. Yield strength is 310 MPa in Final Annealed versus 280 MPa in SRA.
Can FabDigit make parts in 50W470-SRA?
Yes — 50W470-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
- GB/T 2521.1 Cold-rolled non-oriented electrical steel strip and sheet — SAC (China) (2016)
- JIS C 2552 Non-oriented electrical steel strip (50A470 equivalent) — JISC (2014)
- Baosteel non-oriented electrical steel B50A470 product data — Baoshan Iron & Steel (2022)
- ASM Handbook Vol.1 — Properties of Soft Magnetic Fe-Si Alloys — ASM International (1990)
- Mysteel / SMM 50W470 — Mysteel (2026)
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.