Steel Fe-3Si
Fe-3Si (A876) is an iron–silicon soft-magnetic alloy supplied as powder for additive manufacturing of electrical machine cores, and as cold-rolled non-oriented (CRNO) and grain-oriented (GO) sheet conditions.
Reference datasheet — Fe-3Si is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the AB condition
Fe-3Si tempers and conditions
Fe-3Si is supplied in 4 conditions, soft to hard. AB is the default FabDigit quotes; the values on this page are for it.
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 |
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 |
Supply forms, finishes and certifications
Ways Fe-3Si is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
POWDER | Gas-atomised spherical AM feedstock | Printing process |
CRNO | Cold-rolled non-oriented fully processed sheet | Surface finish |
GO | Grain-oriented (Goss texture) sheet, ASTM A876 / GB/T 2521.1 | Surface finish |
What is Fe-3Si?
Fe-3Si (A876) is an iron–silicon soft-magnetic alloy supplied as powder for additive manufacturing of electrical machine cores, and as cold-rolled non-oriented (CRNO) and grain-oriented (GO) sheet conditions. The 3 % silicon content raises electrical resistivity and lowers core loss, which is why it is chosen for printed motor cores and transformer parts with geometries that laminations cannot produce. Mechanical properties are modest and brittle by design: 450 MPa yield, 550 MPa tensile, 3 % elongation, 235 HB (22 HRC), 21 W/m·K and service to about 350 °C. Cold formability is poor and the bare alloy rusts quickly, so insulating coatings and a final magnetic anneal are required. Fe-3Si 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). Fe-3Si has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 52% of steel grades. Elongation at break is 3% and the elastic modulus is 200 GPa (29 Msi).
What is Fe-3Si used for?
- AM motor cores/laminations
- transformer components
- magnetic actuators
Limitations
- Limited ductility — 3%, worse than 99% of steel grades
- Poor heat conductor — 21 W/m·K (12.1 BTU/hr·ft·°F), worse than 95% of steel grades
- Low fracture toughness — 35 MPa·√m (31.9 ksi·√in), worse than 94% of steel grades
- Low electrical conductivity — 3.6 % IACS, worse than 85% of steel grades
- Difficult to machine — 38/100, worse than 80% of steel grades
Fe-3Si properties
Typical room-temperature values for Fe-3Si-AB; bars are the position among steel grades.
Physical3
Fe-3Si 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 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 52% of steel grades. Elongation at break is 3% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
Fe-3Si is rated for continuous service to 350°C (662 °F). It conducts heat at 21 W/m·K (12.1 BTU/hr·ft·°F), worse than 95% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
Fe-3Si conducts electricity at 3.6 % IACS, worse than 85% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of Fe-3Si 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's machinability is fair (38/100, worse than 80% of steel grades); weldability fair (50/100); formability poor (30/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. Fe-3Si is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Fe-3Si
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.
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 |
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.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel Fe-3Si in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- A876
How much does Fe-3Si cost?
Fe-3Si is a high-cost steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Fe-3Si — frequently asked
What is Fe-3Si used for?
Fe-3Si 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?
Fe-3Si has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 52% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is Fe-3Si easy to machine?
Not especially — machinability is rated fair (38/100, worse than 80% 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 be welded?
With care — weldability is rated fair (50/100). 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?
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 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?
Fe-3Si is rated for continuous use to about 350°C (662 °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.
How much does Fe-3Si cost?
Fe-3Si is a high-cost steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.