Aluminum BAlSi-3
ASTM AWS A5.8 BAlSi-3 · EN B Al 4145
BAlSi-3 is an Al-Si-Cu brazing filler to AWS A5.8 (B Al 4145) whose copper addition lowers the melting point relative to plain Al-Si fillers, with liquidus above about 585 °C.
Reference datasheet — BAlSi-3 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 AS-BRAZED condition
BAlSi-3 tempers and conditions
BAlSi-3 is supplied in one standard condition, AS-BRAZED. AS-BRAZED is the default FabDigit quotes; the values on this page are for it.
Supply forms, finishes and certifications
Ways BAlSi-3 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
FLUX-COATED | Flux-coated rod | Supply form |
PREFORM | Stamped rings, washers and shims of BAlSi-3 for fixtured… | Supply form |
ROD | Bare rod / wire | Supply form |
POWDER | Powder / paste | Printing process |
CLAD | Clad sheet | Coating |
What is BAlSi-3?
BAlSi-3 is an Al-Si-Cu brazing filler to AWS A5.8 (B Al 4145) whose copper addition lowers the melting point relative to plain Al-Si fillers, with liquidus above about 585 °C. It is supplied as drawn rod, flux-coated rod, powder, preforms and clad layers for torch and induction brazing of heat-treatable aluminum assemblies, giving roughly 205 MPa tensile, 110 MPa yield, 3 % elongation, 70 HB and 130 W/m·K. Ductility and corrosion resistance are low because of the Cu-rich fillet, and the deposit is hot-crack prone if fusion welded; BAlSi-2 is the choice for corrosion-critical heat exchangers. BAlSi-3 has a density of 2.75 g/cm³ (0.0994 lb/in³), heavier than 67% of aluminum grades. It melts at 521°C (970 °F). BAlSi-3 has a yield strength of 110 MPa (16 ksi) and a tensile strength of 205 MPa (29.7 ksi) — weaker than 81% of aluminum grades. Elongation at break is 3% and the elastic modulus is 71 GPa (10.3 Msi).
What is BAlSi-3 used for?
- torch brazing
- induction brazing
- heat-treatable aluminum assemblies
Limitations
- Hard to polish — 35/100, worse than 98% of aluminum grades
- Needs corrosion protection — 32/100, worse than 94% of aluminum grades
- Low strength — 110 MPa (16 ksi), worse than 81% of aluminum grades
- Limited ductility — 3%, worse than 79% of aluminum grades
- Difficult to weld — 25/100, worse than 76% of aluminum grades
BAlSi-3 properties
Typical room-temperature values for BAlSi-3-AS-BRAZED; bars are the position among aluminum grades.
Physical3
BAlSi-3 has a density of 2.75 g/cm³ (0.0994 lb/in³), heavier than 67% of aluminum grades. It melts at 521°C (970 °F).
Mechanical12
BAlSi-3 has a yield strength of 110 MPa (16 ksi) and a tensile strength of 205 MPa (29.7 ksi) — weaker than 81% of aluminum grades. Elongation at break is 3% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
BAlSi-3 is rated for continuous service to 150°C (302 °F). It conducts heat at 130 W/m·K (75.1 BTU/hr·ft·°F), worse than 65% of aluminum grades. Thermal expansion is 20.5 µm/m·K (11.4 µin/in·°F).
Electrical3
BAlSi-3 conducts electricity at 32 % IACS, worse than 63% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (32/100), worse than 94% of aluminum grades.
Sustainability4
Producing a kilogram of BAlSi-3 takes about 200 MJ of energy and emits 12.5 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 25%.
Manufacturability8
BAlSi-3's machinability is fair (45/100, worse than 72% of aluminum grades); weldability poor (25/100); 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 aluminum family
Yield strength against density for every aluminum grade FabDigit runs. BAlSi-3 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with BAlSi-3
Is BAlSi-3 easy to machine?
Rarely machined; solidified fillets contain abrasive primary Si and are best trimmed with carbide/PCD tooling at high speed and low feed.
Can BAlSi-3 be welded?
Not a fusion-welding filler — use for brazing only above ~585 °C liquidus; fusion welding of the deposit is hot-crack prone due to Cu.
Can BAlSi-3 be formed, bent or molded?
Supplied as drawn rod, powder, preform or clad layer; low ductility limits cold bending of the bare rod, and brazing sheet must be formed before the braze cycle.
BAlSi-3 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 |
|---|---|---|
| Si | 9.3 – 10.7 | 10 |
| Cu | 3.3 – 4.7 | 4 |
| Feimpurity limit | ≤ 0.8 | |
| Mn | ≤ 0.15 | |
| Mgkept low for flux brazing | ≤ 0.15 | |
| Zn | ≤ 0.2 | |
| Cr | ≤ 0.15 | |
| Berestricted for health reasons in some specs | ≤ 8×10⁻⁴ | |
| Others (each) | ≤ 0.05 | |
| Others (total) | ≤ 0.15 | |
| Al | balance |
What surface finishes work on BAlSi-3?
Do not anodize decoratively (dark, blotchy films); remove chloride flux residue with hot-water/nitric rinse, then chromate-convert or paint to protect the Cu-rich fillet.
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-3 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- AWS A5.8 BAlSi-3
- EN / DIN / Werkstoff-Nr.
- B Al 4145
- Other
- 4145
How much does BAlSi-3 cost?
BAlSi-3 is a high-cost aluminum ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
BAlSi-3 — frequently asked
What is BAlSi-3 used for?
BAlSi-3 is typically used for torch brazing, induction brazing and heat-treatable aluminum assemblies. In short: lower-melting Al-Si-Cu filler; torch and induction brazing; low-ductility, Cu-rich fillet.
What is the yield strength of BAlSi-3?
BAlSi-3 has a typical yield strength of 110 MPa (16 ksi) and a tensile strength of 205 MPa (29.7 ksi) — weaker than 81% of aluminum grades.
Is BAlSi-3 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 72% of aluminum grades). Rarely machined; solidified fillets contain abrasive primary Si and are best trimmed with carbide/PCD tooling at high speed and low feed.
Can BAlSi-3 be welded?
Not readily — weldability is rated poor (25/100). Not a fusion-welding filler — use for brazing only above ~585 °C liquidus; fusion welding of the deposit is hot-crack prone due to Cu.
What surface finishes work on BAlSi-3?
Do not anodize decoratively (dark, blotchy films); remove chloride flux residue with hot-water/nitric rinse, then chromate-convert or paint to protect the Cu-rich fillet.
Can BAlSi-3 be formed, bent or molded?
Supplied as drawn rod, powder, preform or clad layer; low ductility limits cold bending of the bare rod, and brazing sheet must be formed before the braze cycle.
What is the maximum service temperature of BAlSi-3?
BAlSi-3 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does BAlSi-3 cost?
BAlSi-3 is a high-cost aluminum ($$$$), 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
- AWS A5.8/A5.8M — Specification for Filler Metals for Brazing and Braze Welding — American Welding Society (2019)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering (Aluminum brazing filler metals) — ASM International (1993)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Brazing Handbook, 5th ed. — American Welding Society (2007)
- GB/T 13815 — (Aluminum brazing filler metals) — SAC (2008)
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.