Aluminum BAlSi-2
ASTM AWS A5.8 BAlSi-2 · EN B Al 4343
BAlSi-2 is a near-eutectic Al-Si brazing filler to AWS A5.8 (B Al 4343, BAl88Si) with a narrow melting range, most often supplied as the cladding layer on aluminum brazing sheet as well as rod, foil and powder.
Reference datasheet — BAlSi-2 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-2 tempers and conditions
BAlSi-2 is supplied in 5 conditions, soft to hard. AS-BRAZED is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
4343 cladding on 3003 brazing sheet, annealed composite | The dominant commercial form: soft 3003-core brazing sheet with 5–15 % per-side 4343 cladding for deep-drawn header plates and tube stock. | 48 | 115 | 25 | 32 HB | 47 % IACS |
Annealed | Standard soft supply condition for coiled 4343 braze wire, cut rods and preform strip that must be bent or stamped. | 55 | 130 | 20 | 42 HB | 43 % IACS |
AS-BRAZEDDefault solidified filler / joint condition | Use for design of the solidified BAlSi-2 fillet or joint after a 595–620 °C braze cycle. | 60 | 165 | 10 | 48 HB | 42 % IACS |
4343-clad brazing sheet, half-hard composite | Use where the pre-braze blank must resist handling damage or hold tight roll-formed tube seams before the braze cycle. | 130 | 150 | 8 | 40 HB | 41 % IACS |
Strain hardened, half hard | Pick when straight rods or wire must feed stiffly through automatic ring-forming and wire-feed equipment. | 145 | 165 | 5 | 52 HB | 41 % IACS |
Supply forms, finishes and certifications
Ways BAlSi-2 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
FOIL | Foil / preform | Supply form |
POWDER | Powder / paste | Printing process |
What is BAlSi-2?
BAlSi-2 is a near-eutectic Al-Si brazing filler to AWS A5.8 (B Al 4343, BAl88Si) with a narrow melting range, most often supplied as the cladding layer on aluminum brazing sheet as well as rod, foil and powder. It is chosen for furnace, CAB and dip brazing of heat-exchanger assemblies, giving joints around 165 MPa tensile, 60 MPa yield, 10 % elongation and 175 W/m·K with 42 % IACS conductivity. Braze temperature must be held at 595-620 °C with tight time control, since overheating dissolves the core and causes filler run-off; use BAlSi-3 where a lower brazing temperature is required. BAlSi-2 has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 577°C (1,071 °F). BAlSi-2 has a yield strength of 60 MPa (8.7 ksi) and a tensile strength of 165 MPa (23.9 ksi) — weaker than 93% of aluminum grades. Elongation at break is 10% and the elastic modulus is 70 GPa (10.2 Msi).
What is BAlSi-2 used for?
- automotive radiators
- HVAC heat exchangers
- furnace brazing of aluminum sheet
Advantages
- Conducts heat well — 175 W/m·K (101.1 BTU/hr·ft·°F), better than 85% of aluminum grades
- High electrical conductivity — 42 % IACS, better than 81% of aluminum grades
Limitations
- Low strength — 60 MPa (8.7 ksi), worse than 93% of aluminum grades
- Hard to polish — 40/100, worse than 91% of aluminum grades
BAlSi-2 properties
Typical room-temperature values for BAlSi-2-AS-BRAZED; bars are the position among aluminum grades.
Physical3
BAlSi-2 has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 577°C (1,071 °F).
Mechanical13
BAlSi-2 has a yield strength of 60 MPa (8.7 ksi) and a tensile strength of 165 MPa (23.9 ksi) — weaker than 93% of aluminum grades. Elongation at break is 10% and the elastic modulus is 70 GPa (10.2 Msi).
Thermal6
BAlSi-2 is rated for continuous service to 150°C (302 °F). It conducts heat at 175 W/m·K (101.1 BTU/hr·ft·°F), better than 85% of aluminum grades. Thermal expansion is 21.6 µm/m·K (12 µin/in·°F).
Electrical3
BAlSi-2 conducts electricity at 42 % IACS, better than 81% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 51% of aluminum grades.
Sustainability4
Producing a kilogram of BAlSi-2 takes about 200 MJ of energy and emits 12.5 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 30%.
Manufacturability8
BAlSi-2's machinability is fair (45/100, worse than 72% of aluminum grades); weldability fair (45/100); formability good (55/100).
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-2 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with BAlSi-2
Is BAlSi-2 easy to machine?
Rarely machined; the near-eutectic Si particles are abrasive, so use PCD or polished-flute carbide, high speed and flood coolant to avoid smearing.
Can BAlSi-2 be welded?
Not a structural weld metal — it is the filler itself; hold braze temperature 595–620 °C with tight time control, since overheating dissolves the core and causes filler run-off.
Can BAlSi-2 be formed, bent or molded?
Monolithic 4343 is low-ductility, but as a 5–15 % cladding on 3003/6951 it deep-draws and roll-forms almost like the core alloy.
BAlSi-2 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 |
|---|---|---|
| Siprimary melting-point depressant | 6.8 – 8.2 | 7.5 |
| Fe | ≤ 0.8 | 0.35 |
| Cu | ≤ 0.25 | 0.05 |
| Mn | ≤ 0.1 | 0.02 |
| Zn | ≤ 0.2 | 0.03 |
| Be0.008 % max in some national versions; restricted for occupational-health reasons | ≤ 8×10⁻⁴ | |
| Others (each)0.15 % total | ≤ 0.05 | |
| Al | balance |
What surface finishes work on BAlSi-2?
Anodizing gives a dark mottled film; prefer chromate-free conversion coating, epoxy/PA e-coat or as-brazed CAB flux residue rinse for corrosion protection.
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-2 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- AWS A5.8 BAlSi-2
- EN / DIN / Werkstoff-Nr.
- B Al 4343
- Other
- 4343
- Similar grades
- BAl88Si
How much does BAlSi-2 cost?
BAlSi-2 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-2 — frequently asked
What is BAlSi-2 used for?
BAlSi-2 is typically used for automotive radiators, HVAC heat exchangers and furnace brazing of aluminum sheet. In short: standard brazing-sheet cladding; narrow Al-Si melting range; high-conductivity braze joints.
What is the yield strength of BAlSi-2?
BAlSi-2 has a typical yield strength of 60 MPa (8.7 ksi) and a tensile strength of 165 MPa (23.9 ksi) — weaker than 93% of aluminum grades. Strength varies by condition: see the 5 listed tempers.
Is BAlSi-2 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 72% of aluminum grades). Rarely machined; the near-eutectic Si particles are abrasive, so use PCD or polished-flute carbide, high speed and flood coolant to avoid smearing.
Can BAlSi-2 be welded?
With care — weldability is rated fair (45/100). Not a structural weld metal — it is the filler itself; hold braze temperature 595–620 °C with tight time control, since overheating dissolves the core and causes filler run-off.
What surface finishes work on BAlSi-2?
Anodizing gives a dark mottled film; prefer chromate-free conversion coating, epoxy/PA e-coat or as-brazed CAB flux residue rinse for corrosion protection.
Can BAlSi-2 be formed, bent or molded?
Monolithic 4343 is low-ductility, but as a 5–15 % cladding on 3003/6951 it deep-draws and roll-forms almost like the core alloy.
What is the maximum service temperature of BAlSi-2?
BAlSi-2 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-2 AS-BRAZED and BAlSi-2-H14?
AS-BRAZED is the default condition — use for design of the solidified BAlSi-2 fillet or joint after a 595–620 °C braze cycle. H14: pick when straight rods or wire must feed stiffly through automatic ring-forming and wire-feed equipment. Yield strength is 60 MPa in AS-BRAZED versus 145 MPa in H14.
How much does BAlSi-2 cost?
BAlSi-2 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 — AWS (2019)
- Aluminum Association Teal Sheets — International Alloy Designations and Chemical Composition Limits for Wrought Aluminum — The Aluminum Association (2018)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering (Aluminum Brazing) — ASM International (1993)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Aluminum brazing sheet and Al-Si filler product data (3003/4343 clad) — Novelis / Granges / Chinese clad-sheet mills (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.