Aluminum BAlSi-4
ASTM AWS A5.8 BAlSi-4 · EN B Al 4047A
BAlSi-4 is a near-eutectic aluminum-silicon brazing filler (nominally 12% Si) classified under AWS A5.8 and also designated B Al 4047A or BAl92Si.
Reference datasheet — BAlSi-4 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 AW condition
BAlSi-4 tempers and conditions
BAlSi-4 is supplied in 4 conditions, soft to hard. AW 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 |
|---|---|---|---|---|---|---|
Annealed | Pick for rolled brazing foil, shim preforms and the clad layer of brazing sheet where maximum ductility for forming is needed. | 60 | 125 | 8 | 45 HB | 39 % IACS |
As fabricated | Pick for remelt ingot, cast rings/washers and preforms fed into dip or furnace brazing lines. | 75 | 160 | 3 | 55 HB | 36 % IACS |
AWDefault As-welded deposit | Default condition: properties of the solidified 4047 deposit or braze fillet after GMAW/GTAW or furnace/dip brazing. | 80 | 170 | 4 | 55 HB | 38 % IACS |
Strain hardened, half hard | Pick for 0.8–1.6 mm MIG spool wire and 2–5 mm TIG rod where drawn stiffness is needed for smooth feeding. | 130 | 195 | 3 | 65 HB | 37 % IACS |
Supply forms, finishes and certifications
Ways BAlSi-4 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
PWD | Powder / paste | Supply form |
What is BAlSi-4?
BAlSi-4 is a near-eutectic aluminum-silicon brazing filler (nominally 12% Si) classified under AWS A5.8 and also designated B Al 4047A or BAl92Si. The high silicon content gives a narrow melting range and high fluidity, so engineers specify it for dip- and vacuum-brazed heat exchangers, cookware and thin fillet joints; it is supplied as wire, rod, foil, clad sheet, preform rings and powder or paste. The as-brazed deposit reaches about 170 MPa tensile and 80 MPa yield with only 4% elongation and 55 HB, thermal conductivity 155 W/m·K, 38% IACS and a service limit near 150 °C, so it is brittle and anodizes dark. Where a slightly lower-silicon clad layer is needed on brazing sheet, BAlSi-5 (4045) is the usual alternative. BAlSi-4 has a density of 2.66 g/cm³ (0.0961 lb/in³), lighter than 84% of aluminum grades. It melts at 577°C (1,071 °F). BAlSi-4 has a yield strength of 80 MPa (11.6 ksi) and a tensile strength of 170 MPa (24.7 ksi) — weaker than 90% of aluminum grades. Elongation at break is 4% and the elastic modulus is 72 GPa (10.4 Msi).
What is BAlSi-4 used for?
- vacuum brazing
- dip brazing
- aluminum cookware
- heat exchanger fin joints
Advantages
- Readily welded — 85/100, better than 79% of aluminum grades
Limitations
- Low fracture toughness — 15 MPa·√m (13.7 ksi·√in), worse than 93% of aluminum grades
- Difficult to machine — 30/100, worse than 92% of aluminum grades
- Hard to polish — 40/100, worse than 91% of aluminum grades
- Low strength — 80 MPa (11.6 ksi), worse than 90% of aluminum grades
BAlSi-4 properties
Typical room-temperature values for BAlSi-4-AW; bars are the position among aluminum grades.
Physical3
BAlSi-4 has a density of 2.66 g/cm³ (0.0961 lb/in³), lighter than 84% of aluminum grades. It melts at 577°C (1,071 °F).
Mechanical14
BAlSi-4 has a yield strength of 80 MPa (11.6 ksi) and a tensile strength of 170 MPa (24.7 ksi) — weaker than 90% of aluminum grades. Elongation at break is 4% and the elastic modulus is 72 GPa (10.4 Msi).
Thermal6
BAlSi-4 is rated for continuous service to 150°C (302 °F). It conducts heat at 155 W/m·K (89.6 BTU/hr·ft·°F), better than 71% of aluminum grades. Thermal expansion is 20.4 µm/m·K (11.3 µin/in·°F).
Electrical3
BAlSi-4 conducts electricity at 38 % IACS, better than 61% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 51% of aluminum grades.
Sustainability4
Producing a kilogram of BAlSi-4 takes about 205 MJ of energy and emits 12.5 kg of CO₂ — more than 76% of aluminum grades. Typical recycled content is 20%.
Manufacturability8
BAlSi-4's machinability is poor (30/100, worse than 92% of aluminum grades); weldability excellent (85/100); formability poor (25/100).
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 aluminum family
Yield strength against density for every aluminum grade FabDigit runs. BAlSi-4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with BAlSi-4
Is BAlSi-4 easy to machine?
High Si makes the deposit abrasive — use polished-flute carbide or PCD tooling, high speed, generous coolant, and expect rapid edge wear on HSS.
Can BAlSi-4 be welded?
Excellent as a GMAW/GTAW filler for 3xx.x castings and 6000 series where hot-crack resistance matters; do not use where the joint must be anodized or where 5000-series-level ductility/marine service is required.
Can BAlSi-4 be formed, bent or molded?
The alloy itself is barely formable (brittle eutectic); form as thin annealed foil or as the clad layer on 3003-core brazing sheet, and keep bend radii generous.
BAlSi-4 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 |
|---|---|---|
| Sinear-eutectic; sets the 577–582 °C melting range | 11 – 13 | 12 |
| Fe | ≤ 0.8 | 0.4 |
| Cu | ≤ 0.3 | 0.05 |
| Mn | ≤ 0.15 | 0.05 |
| Mgkept low for flux (CAB) brazing; higher Mg grades are for vacuum brazing | ≤ 0.1 | 0.02 |
| Zn | ≤ 0.2 | 0.05 |
| BeAWS A5.8 limit; many suppliers offer Be-free | ≤ 8×10⁻⁴ | 0 |
| Others (each) | ≤ 0.05 | |
| Others (total) | ≤ 0.15 | |
| Al | balance |
What surface finishes work on BAlSi-4?
Anodizes dark grey/black and etches unevenly; for cosmetic parts mask fillets, use chemical conversion coating or paint instead of clear anodize.
Surface treatments FabDigit runs on aluminum 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
Equivalent designations
Standards and trade names that resolve to Aluminum BAlSi-4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- AWS A5.8 BAlSi-4
- EN / DIN / Werkstoff-Nr.
- B Al 4047A
- Other
- 4047
- Similar grades
- BAl92Si
How much does BAlSi-4 cost?
BAlSi-4 is a premium-cost aluminum ($$$), cheaper than about 51% 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.
BAlSi-4 — frequently asked
What is BAlSi-4 used for?
BAlSi-4 is typically used for vacuum brazing, dip brazing, aluminum cookware and heat exchanger fin joints. In short: highest-fluidity aluminum braze filler; eutectic 12% Si composition; poor anodizing response.
What is the yield strength of BAlSi-4?
BAlSi-4 has a typical yield strength of 80 MPa (11.6 ksi) and a tensile strength of 170 MPa (24.7 ksi) — weaker than 90% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is BAlSi-4 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 92% of aluminum grades). High Si makes the deposit abrasive — use polished-flute carbide or PCD tooling, high speed, generous coolant, and expect rapid edge wear on HSS.
Can BAlSi-4 be welded?
Yes — weldability is rated excellent (85/100). Excellent as a GMAW/GTAW filler for 3xx.x castings and 6000 series where hot-crack resistance matters; do not use where the joint must be anodized or where 5000-series-level ductility/marine service is required.
What surface finishes work on BAlSi-4?
Anodizes dark grey/black and etches unevenly; for cosmetic parts mask fillets, use chemical conversion coating or paint instead of clear anodize.
Can BAlSi-4 be formed, bent or molded?
The alloy itself is barely formable (brittle eutectic); form as thin annealed foil or as the clad layer on 3003-core brazing sheet, and keep bend radii generous.
What is the maximum service temperature of BAlSi-4?
BAlSi-4 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between BAlSi-4-AW and BAlSi-4-H14?
AW is the default condition — default condition: properties of the solidified 4047 deposit or braze fillet after GMAW/GTAW or furnace/dip brazing. H14: pick for 0.8–1.6 mm MIG spool wire and 2–5 mm TIG rod where drawn stiffness is needed for smooth feeding. Yield strength is 80 MPa in AW versus 130 MPa in H14.
How much does BAlSi-4 cost?
BAlSi-4 is a premium-cost aluminum ($$$), cheaper than about 51% 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
- AWS A5.8/A5.8M — Specification for Filler Metals for Brazing and Braze Welding (BAlSi-4) — American Welding Society (2019)
- AWS A5.10/A5.10M — Bare Aluminum and Aluminum-Alloy Welding Electrodes and Rods (ER4047) — American Welding Society (2021)
- International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets) — 4047/4047A — The Aluminum Association (2018)
- EN ISO 17672 / former EN 1044 AL104 aluminium brazing filler metals — ISO/CEN (2016)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Brazing Handbook, 5th ed. — Aluminum Brazing — American Welding Society (2007)
- ER4047 / BAlSi-4 aluminium filler wire and brazing foil datasheets — various filler-metal producers (2023)
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.