Steel Fe-3Si-SR (Stress relieved)
Heat-treated state
Removes build residual stress and limits distortion after wire-EDM removal, with modest magnetic improvement.
Values for the SR condition
Other Fe-3Si tempers and conditions
Fe-3Si is listed in 4 conditions; see the grade overview at Fe-3Si.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Magnetic anneal | Standard functional condition: grain growth plus C/N removal give minimum core loss and maximum permeability, at the cost of strength. | 330 | 450 | 12 | 180 HB | 24 W/m·K |
hot isostatic pressed then magnetically annealed | Closes residual LPBF porosity for fatigue-critical rotor parts while retaining the annealed magnetic state. | 340 | 470 | 15 | 10 HRC | 3.8 % IACS |
SRThis page Stress relieved | Removes build residual stress and limits distortion after wire-EDM removal, with modest magnetic improvement. | 400 | 500 | 6 | 18 HRC | 3.8 % IACS |
ABDefault As built (as printed) | Highest strength and hardness but high residual stress, fine cells and elevated core loss — use only for dimensional/mechanical trials. | 450 | 550 | 3 | 22 HRC | 21 W/m·K |
What is Fe-3Si-SR?
Fe-3Si-SR is Fe-3Si heat treated to SR — removes build residual stress and limits distortion after wire-EDM removal, with modest magnetic improvement. Fe-3Si-SR has a yield strength of 400 MPa (58 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 60% of steel grades. Elongation at break is 6% and the elastic modulus is 200 GPa (29 Msi). Fe-3Si-SR has a density of 7.65 g/cm³ (0.276 lb/in³), lighter than 97% of steel grades. It melts at 1,470°C (2,678 °F). AB is the default condition FabDigit quotes; SR is available on request or by drawing note.
Limitations
- Limited ductility — 6%, worse than 97% of steel grades
- Low fracture toughness — 40 MPa·√m (36.4 ksi·√in), worse than 92% of steel grades
- Poor heat conductor — 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades
- Low electrical conductivity — 3.8 % IACS, worse than 84% of steel grades
Fe-3Si-SR properties
Typical room-temperature values for Fe-3Si-SR; 24 are specific to this condition. Other listed values are Fe-3Si reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
Fe-3Si-SR has a density of 7.65 g/cm³ (0.276 lb/in³), lighter than 97% of steel grades. It melts at 1,470°C (2,678 °F).
Mechanical16
Fe-3Si-SR has a yield strength of 400 MPa (58 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 60% of steel grades. Elongation at break is 6% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
Fe-3Si-SR is rated for continuous service to 400°C (752 °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
Fe-3Si-SR conducts electricity at 3.8 % IACS, worse than 84% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of Fe-3Si-SR takes about 35 MJ of energy and emits 2.4 kg of CO₂ — more than 87% of steel grades. Typical recycled content is 25%.
Manufacturability7
Fe-3Si-SR's machinability is fair (43/100, worse than 71% of steel grades); weldability fair (53/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Fe-3Si-SR
Is Fe-3Si easy to machine?
Abrasive and burr-prone — use sharp coated carbide, positive rake, generous coolant and light finishing passes; wire-EDM is usual for separating printed cores from the plate.
Can Fe-3Si be welded?
Weldable by laser/TIG with low heat input, but HAZ grain growth and stress raise core loss and embrittle the joint — avoid weld beads across the magnetic circuit and re-anneal if possible.
Can Fe-3Si be formed, bent or molded?
Cold formability is poor above ~2.5% Si; punch/laser-cut thin laminations instead. LPBF prints well on a 200–500 °C heated plate with slow cooling to avoid solidification cracking.
What surface finishes work on Fe-3Si?
Bare Fe-3Si rusts quickly — apply phosphate/inorganic C-5 insulating coating, e-coat, varnish or epoxy impregnation; parts can be shot-peened or polished but any cold work must precede the final magnetic anneal.
Fe-3Si 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 | 2.5 – 3.5 | 3 |
| Ckept ultra-low; decarburised during magnetic anneal | ≤ 0.01 | 0.01 |
| Mn | ≤ 0.3 | 0.15 |
| Aloptional in NGO grades; deoxidation / added resistivity | ≤ 0.5 | 0.2 |
| P | ≤ 0.03 | 0.01 |
| S | ≤ 0.01 | 0 |
| N | ≤ 0.01 | 0 |
| OAM powder limit; higher O degrades magnetics | ≤ 0.05 | 0.02 |
| Fe | balance | — |
Fe-3Si-SR — frequently asked
What is Fe-3Si-SR used for?
Fe-3Si-SR is typically used for AM motor cores/laminations, transformer components and magnetic actuators. In short: low-core-loss AM alloy; soft-magnetic motor core material; printable silicon steel.
What is the yield strength of Fe-3Si-SR?
Fe-3Si-SR has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is Fe-3Si-SR easy to machine?
Not especially — machinability is rated fair (43/100, worse than 71% of steel grades). Abrasive and burr-prone — use sharp coated carbide, positive rake, generous coolant and light finishing passes; wire-EDM is usual for separating printed cores from the plate.
Can Fe-3Si-SR be welded?
With care — weldability is rated fair (53/100). Weldable by laser/TIG with low heat input, but HAZ grain growth and stress raise core loss and embrittle the joint — avoid weld beads across the magnetic circuit and re-anneal if possible.
What surface finishes work on Fe-3Si-SR?
Bare Fe-3Si rusts quickly — apply phosphate/inorganic C-5 insulating coating, e-coat, varnish or epoxy impregnation; parts can be shot-peened or polished but any cold work must precede the final magnetic anneal.
Can Fe-3Si-SR be formed, bent or molded?
Cold formability is poor above ~2.5% Si; punch/laser-cut thin laminations instead. LPBF prints well on a 200–500 °C heated plate with slow cooling to avoid solidification cracking.
What is the maximum service temperature of Fe-3Si-SR?
Fe-3Si-SR is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Fe-3Si-AB and Fe-3Si-MA?
AB is the default condition — highest strength and hardness but high residual stress, fine cells and elevated core loss — use only for dimensional/mechanical trials. MA: standard functional condition: grain growth plus C/N removal give minimum core loss and maximum permeability, at the cost of strength. Yield strength is 450 MPa in AB versus 330 MPa in MA.
Sources
- ASTM A876 — Flat-Rolled, Grain-Oriented, Silicon-Iron, Electrical Steel, Fully Processed Types — ASTM International (2018)
- ASTM A677 — Nonoriented Electrical Steel Fully Processed Types — ASTM International (2020)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (Magnetically Soft Materials) — ASM International (1990)
- Ferromagnetism (Bozorth) — Fe-Si alloys — IEEE Press (1993)
- Gas-atomised soft magnetic Fe-Si powder for additive manufacturing — Höganäs / Sandvik Osprey (2023)
- Published LPBF Fe-3wt%Si mechanical and magnetic property studies — Additive Manufacturing / JMMM (2022)
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.