Steel 27W140-SRA
Heat-treated state
EN 27W140
SRA = stress-relief annealed after stamping
Use when punching/burr stresses have raised core loss: SRA recovers magnetic performance but softens the laminations and requires a heat-stable coating.
Values for the SRA condition
What is 27W140-SRA?
27W140-SRA is 27W140 heat treated to SRA — use when punching/burr stresses have raised core loss: SRA recovers magnetic performance but softens the laminations and requires a heat-stable coating. 27W140-SRA has a yield strength of 310 MPa (45 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 83% of steel grades. Elongation at break is 14% and the elastic modulus is 190 GPa (27.6 Msi). 27W140-SRA has a density of 7.6 g/cm³ (0.275 lb/in³), lighter than 98% of steel grades. It melts at 1,500°C (2,732 °F).
Limitations
- 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 — 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades
- Low electrical conductivity — 2.9 % IACS, worse than 93% of steel grades
- Difficult to machine — 33/100, worse than 86% of steel grades
27W140-SRA properties
Typical room-temperature values for 27W140-SRA; 5 are specific to this condition. Other listed values are 27W140 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
27W140-SRA has a density of 7.6 g/cm³ (0.275 lb/in³), lighter than 98% of steel grades. It melts at 1,500°C (2,732 °F).
Mechanical11
27W140-SRA has a yield strength of 310 MPa (45 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 83% of steel grades. Elongation at break is 14% and the elastic modulus is 190 GPa (27.6 Msi).
Thermal6
27W140-SRA is rated for continuous service to 200°C (392 °F). It conducts heat at 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
27W140-SRA conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of 27W140-SRA takes about 34 MJ of energy and emits 2.5 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
27W140-SRA's machinability is poor (33/100, worse than 86% of steel grades); weldability fair (40/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 27W140-SRA
Is 27W140 easy to machine?
Rarely machined — process by precision blanking/punching with carbide or PM tooling and tight clearance (~5 % of thickness); the abrasive high-Si strip wears dies fast and burrs must be minimal to keep core loss low.
Can 27W140 be welded?
Laser or TIG tacking of stacks is possible but weld beads short-circuit laminations and locally destroy magnetic performance; prefer interlocking, adhesive bonding or banding.
Can 27W140 be formed, bent or molded?
Good punchability but limited bendability at 0.27 mm high-Si; avoid tight bends, control coil set and de-burr, and stress-relief anneal at 750–820 °C in protective atmosphere if forming stresses are significant.
What surface finishes work on 27W140?
Supplied pre-coated (inorganic C-5, semi-organic C-6 or self-bonding); no anodising. Bare strip must be oiled or varnished, and cut edges of any variant should be impregnated/varnished against rust.
27W140 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 | 2.9 – 3.5 | 3.2 |
| Alfurther resistivity increase, deoxidiser | 0.3 – 1 | 0.6 |
| Mn | 0.1 – 0.5 | 0.25 |
| Ckept ultra-low to avoid magnetic ageing | ≤ 0.01 | 0 |
| S | ≤ 0.01 | 0 |
| P | ≤ 0.03 | 0.01 |
| N | ≤ 0 | 0 |
| Fe | balance |
27W140-SRA — frequently asked
What is 27W140-SRA used for?
27W140-SRA is typically used for high-speed motors, servo motors and aerospace generators. In short: thin-gauge low-loss lamination; built for high-frequency motors; self-bonding coating option.
What is the yield strength of 27W140-SRA?
27W140-SRA has a typical yield strength of 310 MPa (45 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 83% of steel grades.
Is 27W140-SRA easy to machine?
Not especially — machinability is rated poor (33/100, worse than 86% of steel grades). Rarely machined — process by precision blanking/punching with carbide or PM tooling and tight clearance (~5 % of thickness); the abrasive high-Si strip wears dies fast and burrs must be minimal to keep core loss low.
Can 27W140-SRA be welded?
With care — weldability is rated fair (40/100). Laser or TIG tacking of stacks is possible but weld beads short-circuit laminations and locally destroy magnetic performance; prefer interlocking, adhesive bonding or banding.
What surface finishes work on 27W140-SRA?
Supplied pre-coated (inorganic C-5, semi-organic C-6 or self-bonding); no anodising. Bare strip must be oiled or varnished, and cut edges of any variant should be impregnated/varnished against rust.
Can 27W140-SRA be formed, bent or molded?
Good punchability but limited bendability at 0.27 mm high-Si; avoid tight bends, control coil set and de-burr, and stress-relief anneal at 750–820 °C in protective atmosphere if forming stresses are significant.
What is the maximum service temperature of 27W140-SRA?
27W140-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
- GB/T 2521.1 Cold-rolled non-oriented electrical steel strip (2016)
- IEC 60404-8-4 Cold-rolled non-oriented electrical steel sheet and strip — IEC (2013)
- ASTM A677 / A683 Non-oriented electrical steel, fully processed and semi-processed — ASTM (2020)
- ASM Handbook Vol.1 — Magnetically Soft Materials — ASM International (1990)
- Thin-gauge high-grade non-oriented electrical steel strip data (0.20–0.30 mm classes) — Baosteel / Shougang (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.