Steel B50A470 · heat-treated state
Steel B50A470-SRA
Properties of the SRA condition, compared with the other B50A470 tempers.
Pick when punching/edge stresses must be recovered: core loss drops and permeability rises by roughly 5–15 %, at the cost of softer, more distortion-prone laminations.
What is B50A470-SRA?
B50A470-SRA is B50A470 heat treated to SRA — pick when punching/edge stresses must be recovered: core loss drops and permeability rises by roughly 5–15 %, at the cost of softer, more distortion-prone laminations. B50A470-SRA has a yield strength of 255 MPa (37 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 93% of steel grades. Elongation at break is 34% and the elastic modulus is 200 GPa (29 Msi). B50A470-SRA has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 95% of steel grades. It melts at 1,500°C (2,732 °F). Final Annealed is the default condition FabDigit quotes; SRA is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 34%, better than 96% of steel grades
- Forms and bends easily — 78/100, better than 91% of steel grades
Limitations
- Low strength — 255 MPa (37 ksi), worse than 93% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Poor heat conductor — 28 W/m·K (16.2 BTU/hr·ft·°F), worse than 85% of steel grades
- Hard to polish — 45/100, worse than 84% of steel grades
- Low electrical conductivity — 4.3 % IACS, worse than 83% of steel grades
B50A470-SRA properties
Typical room-temperature values for B50A470-SRA — 8 properties are specific to this condition; the rest are grade-level values shared by every B50A470 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
B50A470-SRA has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 95% of steel grades. It melts at 1,500°C (2,732 °F).
Mechanical12
B50A470-SRA has a yield strength of 255 MPa (37 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 93% of steel grades. Elongation at break is 34% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
B50A470-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
B50A470-SRA conducts electricity at 4.3 % IACS, worse than 83% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of B50A470-SRA takes about 32 MJ of energy and emits 2.4 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 20%.
Manufacturability6
B50A470-SRA's machinability is good (55/100, better than 62% of steel grades); weldability fair (50/100); formability very good (78/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other B50A470 tempers and conditions
B50A470 is also supplied in 2 other conditions. The full side-by-side table is on the B50A470 overview.
- Final AnnealedDefaultStandard as-shipped fully-processed condition: stamp laminations and stack directly, guaranteed P1.5/50 ≤ 4.70 W/kg at 0.50 mm.305 MPa yield · 165 HV
- SRAPick when punching/edge stresses must be recovered: core loss drops and permeability rises by roughly 5–15 %, at the cost of softer, more distortion-prone laminations.255 MPa yield · 76 HRB
Working with B50A470-SRA
Is B50A470 easy to machine?
Primarily progressive-die punched or laser/wire cut; keep punch clearance ~5–8 % of thickness and tools sharp, since burrs and cut-edge damage directly raise core loss.
Can B50A470 be welded?
Laser or micro-TIG tack welding of stacks is feasible but each weld bridges laminations and increases eddy-current loss — prefer interlocking, bonding or cleats.
Can B50A470 be formed, bent or molded?
Excellent blanking and light bending at 0.50 mm; avoid heavy cold work near tooth roots, and stress-relief anneal at 750–800 °C in a neutral, decarburising-free atmosphere if magnetics are critical.
What surface finishes work on B50A470?
Supplied with a thin semi-organic/inorganic insulating coating (C5/C6 type) that also acts as a punching lubricant; do not shot blast or pickle, and mask coating loss areas from corrosion in humid storage.
B50A470 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 |
|---|---|---|
| Cultra-low to avoid magnetic ageing | ≤ 0.01 | 0 |
| Siraises resistivity, lowers eddy-current loss | 1.4 – 2.3 | 1.9 |
| Al | 0.2 – 0.6 | 0.4 |
| Mn | 0.15 – 0.5 | 0.3 |
| P | ≤ 0.06 | 0.02 |
| S | ≤ 0.01 | 0 |
| N | ≤ 0 | 0 |
| Fe | balance | — |
B50A470-SRA — frequently asked
What is B50A470-SRA used for?
B50A470-SRA is typically used for motor stator and rotor laminations, distribution transformer cores, generator and alternator laminations, pump and fan motor cores, reactor and choke cores and solenoid and relay cores. In short: workhorse electrical coil.
What is the yield strength of B50A470-SRA?
B50A470-SRA has a typical yield strength of 255 MPa (37 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 93% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is B50A470-SRA easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Primarily progressive-die punched or laser/wire cut; keep punch clearance ~5–8 % of thickness and tools sharp, since burrs and cut-edge damage directly raise core loss.
Can B50A470-SRA be welded?
With care — weldability is rated fair (50/100). Laser or micro-TIG tack welding of stacks is feasible but each weld bridges laminations and increases eddy-current loss — prefer interlocking, bonding or cleats.
What surface finishes work on B50A470-SRA?
Supplied with a thin semi-organic/inorganic insulating coating (C5/C6 type) that also acts as a punching lubricant; do not shot blast or pickle, and mask coating loss areas from corrosion in humid storage.
Can B50A470-SRA be formed, bent or molded?
Excellent blanking and light bending at 0.50 mm; avoid heavy cold work near tooth roots, and stress-relief anneal at 750–800 °C in a neutral, decarburising-free atmosphere if magnetics are critical.
What is the maximum service temperature of B50A470-SRA?
B50A470-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 B50A470 Final Annealed and B50A470-SRA?
Final Annealed is the default condition — standard as-shipped fully-processed condition: stamp laminations and stack directly, guaranteed P1.5/50 ≤ 4.70 W/kg at 0.50 mm. SRA: pick when punching/edge stresses must be recovered: core loss drops and permeability rises by roughly 5–15 %, at the cost of softer, more distortion-prone laminations. Yield strength is 305 MPa in Final Annealed versus 255 MPa in SRA.
Can FabDigit make parts in B50A470-SRA?
Yes — B50A470-SRA is available for sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- JIS C 2552 — Non-oriented electrical steel strip — JSA (2019)
- EN 10106 — Cold rolled non-oriented electrical steel strip and sheet delivered in the fully processed state — CEN (2015)
- Baosteel Electrical Steel Product Catalogue (B50A series) — Baoshan Iron & Steel (2022)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys (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.