Aluminum 4043
AA 4043 · UNS A94043 · EN AW-4043, AW 4043 · JIS A4043 · GB SAlSi-1
4043 is a non-heat-treatable Al-Si alloy with about 5 % silicon (EN AW-4043, AlSi5, ER4043 to AWS A5.10), supplied almost entirely as welding wire, TIG rod and brazing product.
4043 tempers and conditions
4043 is supplied in 3 conditions, soft to hard.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Fully softened wire/rod for maximum ductility, coiling and hand-feeding; also the reference condition for physical property data. | 55 | 145 | 22 | 40 HB | 42 % IACS |
As-welded deposit | Design basis for joints made with 4043 filler; note strength drops further in the HAZ of 6061-T6 base metal. | 55 | 165 | 8 | 45 HB | 40 % IACS |
As fabricated | Standard supply condition for ER4043 spooled MIG wire and TIG cut lengths; cold drawn for column strength and feedability. | 120 | 180 | 12 | 50 HB | 42 % IACS |
What is 4043?
4043 is a non-heat-treatable Al-Si alloy with about 5 % silicon (EN AW-4043, AlSi5, ER4043 to AWS A5.10), supplied almost entirely as welding wire, TIG rod and brazing product. Silicon gives a fluid weld pool, wide freezing range and low hot-cracking tendency, which makes it the standard filler for 6000-series extrusions and sheet and for most Al-Si castings, with better elevated-temperature service than 5356. Limits are low as-welded strength (UTS about 145–165 MPa), limited elongation, fair machinability and dark grey anodizing caused by the silicon phase, so it is unsuitable for cosmetic anodized joints. 4043 has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 574°C (1,065 °F). 4043 has a yield strength of 120 MPa (17.4 ksi) and a tensile strength of 180 MPa (26.1 ksi) — weaker than 77% of aluminum grades. Elongation at break is 12% and the elastic modulus is 69 GPa (10 Msi).
What is 4043 used for?
- Weld filler wire
- Brazing strip
- GTAW rod for 6000-series extrusions and sheet
- Weld repair of Al-Si castings
- GMAW spool wire for aluminium fabrication
- Joining of aluminium frames and enclosures
Advantages
- Readily welded — 95/100, better than 99% of aluminum grades
- High service temperature — 200°C (392 °F), better than 90% of aluminum grades
- Forms and bends easily — 70/100, better than 83% of aluminum grades
- High electrical conductivity — 42 % IACS, better than 81% of aluminum grades
- Conducts heat well — 163 W/m·K (94.2 BTU/hr·ft·°F), better than 77% of aluminum grades
Limitations
- Difficult to machine — 30/100, worse than 92% of aluminum grades
- Hard to polish — 40/100, worse than 91% of aluminum grades
- Low strength — 120 MPa (17.4 ksi), worse than 77% of aluminum grades
4043 properties
Typical room-temperature values; bars are the position among aluminum grades.
Physical3
4043 has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 574°C (1,065 °F).
Mechanical10
4043 has a yield strength of 120 MPa (17.4 ksi) and a tensile strength of 180 MPa (26.1 ksi) — weaker than 77% of aluminum grades. Elongation at break is 12% and the elastic modulus is 69 GPa (10 Msi).
Thermal6
4043 is rated for continuous service to 200°C (392 °F). It conducts heat at 163 W/m·K (94.2 BTU/hr·ft·°F), better than 77% of aluminum grades. Thermal expansion is 22 µm/m·K (12.2 µin/in·°F).
Electrical3
4043 conducts electricity at 42 % IACS, better than 81% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (58/100), better than 57% of aluminum grades.
Sustainability4
Producing a kilogram of 4043 takes about 200 MJ of energy and emits 12 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 30%.
Manufacturability8
4043's machinability is poor (30/100, worse than 92% of aluminum grades); weldability excellent (95/100); formability very good (70/100).
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. 4043 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 4043
Is 4043 easy to machine?
Rarely machined; the eutectic Si makes it abrasive yet gummy — use polished-flute carbide, high speed, low feed and generous lubrication.
Can 4043 be welded?
Designed as a GMAW/GTAW filler for 6000-series extrusions and Al-Si castings: low hot-cracking sensitivity, wide freezing range, good wetting; do not use where post-weld anodized colour match is required.
Can 4043 be formed, bent or molded?
Soft and ductile in O temper — coils and straightens easily; hard-drawn F wire has better column strength for spool feeding but less bend ductility.
Manufacturability
The process limits FabDigit applies to 4043. Every 4043 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Good30 / 100 |
|---|---|
| ISO material group | N.1 |
| Cutting speed (rough / finish) | 350 / 420 m/min |
| Minimum wall | 0.5 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 8× diameter |
| Best surface (machined / polished) | Ra 0.8 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Excellent70 / 100 |
|---|---|
| Weldability | Excellent95 / 100 |
4043 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 | 4.5 – 6 | 5.2 |
| Fe | ≤ 0.8 | 0.3 |
| Cu | ≤ 0.3 | 0.05 |
| Mn | ≤ 0.05 | |
| Mg | ≤ 0.05 | |
| Zn | ≤ 0.1 | |
| Ti | ≤ 0.2 | |
| Befiller-metal limit per AWS A5.10 | ≤ 3×10⁻⁴ | |
| Others (each) | ≤ 0.05 | |
| Others (total) | ≤ 0.15 | |
| Al | balance |
What surface finishes work on 4043?
Anodizes dark grey/black because of silicon; weld beads take chemical etch unevenly — paint, powder coat or mechanical finish for appearance parts.
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).
Passivation
Conversion Coating
PVD Coating
Equivalent designations
Standards and trade names that resolve to Aluminum 4043 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- A94043
- Aluminum Association
- AA4043
- EN / DIN / Werkstoff-Nr.
- AW-4043AW 4043AlSi5
- GB (China)
- SAlSi-1
- JIS
- A4043
- Trade names
- ER4043 / AWS A5.10
- Also called
- ER4043
How much does 4043 cost?
4043 is a standard-cost aluminum ($$), cheaper than about 81% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
4043 — frequently asked
What is 4043 used for?
4043 is typically used for weld filler wire, brazing strip, GTAW rod for 6000-series extrusions and sheet, weld repair of Al-Si castings, GMAW spool wire for aluminium fabrication and joining of aluminium frames and enclosures. In short: common 5% Si filler wire; all-position weld.
What is the yield strength of 4043?
4043 has a typical yield strength of 120 MPa (17.4 ksi) and a tensile strength of 180 MPa (26.1 ksi) — weaker than 77% of aluminum grades. Strength varies by condition: see the 3 listed tempers.
Is 4043 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 92% of aluminum grades). Rarely machined; the eutectic Si makes it abrasive yet gummy — use polished-flute carbide, high speed, low feed and generous lubrication.
Can 4043 be welded?
Yes — weldability is rated excellent (95/100). Designed as a GMAW/GTAW filler for 6000-series extrusions and Al-Si castings: low hot-cracking sensitivity, wide freezing range, good wetting; do not use where post-weld anodized colour match is required.
What surface finishes work on 4043?
Anodizes dark grey/black because of silicon; weld beads take chemical etch unevenly — paint, powder coat or mechanical finish for appearance parts.
Can 4043 be formed, bent or molded?
Soft and ductile in O temper — coils and straightens easily; hard-drawn F wire has better column strength for spool feeding but less bend ductility.
What is the maximum service temperature of 4043?
4043 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 4043 cost?
4043 is a standard-cost aluminum ($$), cheaper than about 81% 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 4043?
Yes — 4043 is available for CNC machining and 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
- AWS A5.10/A5.10M — Bare Aluminum and Aluminum-Alloy Welding Electrodes and Rods — AWS (2021)
- International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets) — The Aluminum Association (2018)
- EN ISO 18273 — Welding consumables: wire and rods for aluminium and aluminium alloys — CEN/ISO (2016)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- AWS D1.2/D1.2M — Structural Welding Code, Aluminum — AWS (2014)
- ER4043 aluminium welding wire datasheets — Lincoln Electric / ESAB / (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.