Aluminum 4343
AA 4343 · UNS A94343 · EN AW-4343, AW 4343
4343 is a wrought Al-Si alloy containing about 7.5 % Si with a low melting range (solidus about 577 °C, liquidus about 613 °C), used mainly as the cladding layer on aluminium heat-exchanger brazing sheet and as brazing wire and shim.
4343 tempers and conditions
4343 is supplied in 4 conditions, soft to hard.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Standard stocked condition for braze filler sheet/foil and clad brazing sheet blanks that must be deep drawn or formed before brazing. | 55 | 130 | 20 | 40 HB | 42 % IACS |
Strain hardened and partially annealed, half hard | Pick when H14-level strength is needed but bending/forming ductility must be preserved (typical for clad brazing strip). | 145 | 175 | 7 | 48 HB | 41 % IACS |
Strain hardened, half hard | Choose for braze foil/shim and clad sheet needing extra stiffness and flatness in handling, with only light forming. | 165 | 185 | 4 | 52 HB | 41 % IACS |
Strain hardened, full hard | Only for thin braze foil/tape rolled to final gauge without intermediate anneal; almost no formability. | 200 | 215 | 2 | 58 HB | 41 % IACS |
What is 4343?
4343 is a wrought Al-Si alloy containing about 7.5 % Si with a low melting range (solidus about 577 °C, liquidus about 613 °C), used mainly as the cladding layer on aluminium heat-exchanger brazing sheet and as brazing wire and shim. It is chosen because that melting range sits just below 3003 and 3005 core alloys, so it flows freely and forms dense fillets in vacuum or CAB (NOCOLOK) furnaces. On its own it is weak with limited ductility, the silicon darkens anodic films and promotes built-up edge in machining, so it is not used as a load-bearing structural material. 4045 is the usual higher-silicon alternative cladding alloy. 4343 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). 4343 has a yield strength of 55 MPa (7.98 ksi) and a tensile strength of 130 MPa (18.9 ksi) — weaker than 94% of aluminum grades. Elongation at break is 20% and the elastic modulus is 69 GPa (10 Msi).
What is 4343 used for?
- Brazing sheet cladding for heat exchangers
- Radiator and charge-air cooler tube stock
- Evaporator and condenser plates
- Brazing filler wire and rod
- Brazing shim and preforms
- Oil cooler assemblies
Advantages
- Ductile — tolerates forming and impact — 20%, better than 89% of aluminum grades
- Conducts heat well — 180 W/m·K (104 BTU/hr·ft·°F), better than 86% of aluminum grades
- High electrical conductivity — 42 % IACS, better than 81% of aluminum grades
- Forms and bends easily — 60/100, better than 77% of aluminum grades
Limitations
- Low strength — 55 MPa (7.98 ksi), worse than 94% of aluminum grades
- Difficult to machine — 32/100, worse than 89% of aluminum grades
- Hard to polish — 45/100, worse than 76% of aluminum grades
4343 properties
Typical room-temperature values; bars are the position among aluminum grades.
Physical3
4343 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).
Mechanical10
4343 has a yield strength of 55 MPa (7.98 ksi) and a tensile strength of 130 MPa (18.9 ksi) — weaker than 94% of aluminum grades. Elongation at break is 20% and the elastic modulus is 69 GPa (10 Msi).
Thermal6
4343 is rated for continuous service to 150°C (302 °F). It conducts heat at 180 W/m·K (104 BTU/hr·ft·°F), better than 86% of aluminum grades. Thermal expansion is 21.6 µm/m·K (12 µin/in·°F).
Electrical3
4343 conducts electricity at 42 % IACS, better than 81% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), better than 67% of aluminum grades.
Sustainability4
Producing a kilogram of 4343 takes about 200 MJ of energy and emits 12 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 25%.
Manufacturability8
4343's machinability is poor (32/100, worse than 89% of aluminum grades); weldability good (55/100); formability good (60/100).
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. 4343 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 4343
Is 4343 easy to machine?
Soft and gummy with abrasive Si particles — use polished high-rake carbide, high speed, flood lubricant to avoid built-up edge; rarely machined as a structural part.
Can 4343 be welded?
Primarily a filler/cladding alloy: excellent flow in CAB (NOCOLOK) and vacuum brazing at 590–610 °C; as a base metal it is weak and hot-short, so joints are made by brazing rather than fusion welding.
Can 4343 be formed, bent or molded?
O and H2x tempers roll and draw well as clad layers; keep total cold work low in H1x tempers and avoid tight bends where Si particles nucleate cracks.
Manufacturability
The process limits FabDigit applies to 4343. Every 4343 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
Sheet metal
| Formability | Excellent60 / 100 |
|---|---|
| Weldability | Excellent55 / 100 |
4343 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 |
|---|---|---|
| Siprovides low melting range for brazing | 6.8 – 8.2 | 7.5 |
| Fe | ≤ 0.8 | 0.35 |
| Cu | ≤ 0.25 | |
| Mn | ≤ 0.1 | |
| Zn | ≤ 0.2 | |
| Others (each)per AA limits | ≤ 0.05 | |
| Others (total) | ≤ 0.15 | |
| Al | balance |
What surface finishes work on 4343?
Anodizing gives dark, blotchy films (avoid for cosmetics); chemical conversion coating or painting after brazing, and flux residues must be washed off to prevent staining.
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).
Equivalent designations
Standards and trade names that resolve to Aluminum 4343 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- A94343
- Aluminum Association
- AA4343
- EN / DIN / Werkstoff-Nr.
- AW-4343AW 4343AlSi7.5
- Also called
- BAlSi-2
How much does 4343 cost?
4343 is a standard-cost aluminum ($$), cheaper than about 80% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
4343 — frequently asked
What is 4343 used for?
4343 is typically used for brazing sheet cladding for heat exchangers, radiator and charge-air cooler tube stock, evaporator and condenser plates, brazing filler wire and rod, brazing shim and preforms and oil cooler assemblies. In short: brazing clad alloy; 7% Si skin.
What is the yield strength of 4343?
4343 has a typical yield strength of 55 MPa (7.98 ksi) and a tensile strength of 130 MPa (18.9 ksi) — weaker than 94% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is 4343 easy to machine?
Not especially — machinability is rated poor (32/100, worse than 89% of aluminum grades). Soft and gummy with abrasive Si particles — use polished high-rake carbide, high speed, flood lubricant to avoid built-up edge; rarely machined as a structural part.
Can 4343 be welded?
Yes — weldability is rated good (55/100). Primarily a filler/cladding alloy: excellent flow in CAB (NOCOLOK) and vacuum brazing at 590–610 °C; as a base metal it is weak and hot-short, so joints are made by brazing rather than fusion welding.
What surface finishes work on 4343?
Anodizing gives dark, blotchy films (avoid for cosmetics); chemical conversion coating or painting after brazing, and flux residues must be washed off to prevent staining.
Can 4343 be formed, bent or molded?
O and H2x tempers roll and draw well as clad layers; keep total cold work low in H1x tempers and avoid tight bends where Si particles nucleate cracks.
What is the maximum service temperature of 4343?
4343 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 4343 cost?
4343 is a standard-cost aluminum ($$), cheaper than about 80% 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.
Can FabDigit make parts in 4343?
Yes — 4343 is available for sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets) — The Aluminum Association (2018)
- EN 573-3 Aluminium and aluminium alloys — Chemical composition — CEN (2019)
- ASM Handbook Vol. 2: Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol. 6: Welding, Brazing and Soldering (aluminium brazing) — ASM International (1993)
- Aluminium brazing sheet (3003 core / 4343 clad) product data — Constellium / Granges (2022)
- MatWeb aluminium 4343 alloy entries — MatWeb LLC (2024)
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.