Aluminum 4043 · temper
Aluminum 4043-O
Properties of the O condition, compared with the other 4043 tempers.
Fully softened wire/rod for maximum ductility, coiling and hand-feeding; also the reference condition for physical property data.
What is 4043-O?
4043-O is 4043 in the O temper — fully softened wire/rod for maximum ductility, coiling and hand-feeding; also the reference condition for physical property data. 4043-O has a yield strength of 55 MPa (7.98 ksi) and a tensile strength of 145 MPa (21 ksi) — weaker than 94% of aluminum grades. Elongation at break is 22% and the elastic modulus is 69 GPa (10 Msi). 4043-O 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).
Advantages
- Readily welded — 95/100, better than 99% of aluminum grades
- Ductile — tolerates forming and impact — 22%, better than 91% of aluminum grades
- High service temperature — 200°C (392 °F), better than 90% of aluminum grades
- Forms and bends easily — 80/100, better than 89% of aluminum grades
- High electrical conductivity — 42 % IACS, better than 81% of aluminum grades
Limitations
- Difficult to machine — 25/100, worse than 96% of aluminum grades
- Low strength — 55 MPa (7.98 ksi), worse than 94% of aluminum grades
- Hard to polish — 40/100, worse than 90% of aluminum grades
4043-O properties
Typical room-temperature values for 4043-O — 10 properties are specific to this condition; the rest are grade-level values shared by every 4043 temper. Each bar shows where the value sits among the aluminum grades in FabDigit's library — further right is higher.
Physical3
4043-O 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-O has a yield strength of 55 MPa (7.98 ksi) and a tensile strength of 145 MPa (21 ksi) — weaker than 94% of aluminum grades. Elongation at break is 22% and the elastic modulus is 69 GPa (10 Msi).
Thermal6
4043-O 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-O 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-O 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-O's machinability is poor (25/100, worse than 96% of aluminum grades); weldability excellent (95/100); formability very good (80/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 4043 tempers and conditions
4043 is also supplied in 2 other conditions. The full side-by-side table is on the 4043 overview.
- FStandard supply condition for ER4043 spooled MIG wire and TIG cut lengths; cold drawn for column strength and feedability.120 MPa yield · 50 HB
- OFully softened wire/rod for maximum ductility, coiling and hand-feeding; also the reference condition for physical property data.55 MPa yield · 40 HB
- AWDesign basis for joints made with 4043 filler; note strength drops further in the HAZ of 6061-T6 base metal.55 MPa yield · 45 HB
Working with 4043-O
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 6xxx 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.
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.
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 | — |
4043-O — frequently asked
What is 4043-O used for?
4043-O is typically used for weld filler wire, brazing strip, GTAW rod for 6xxx 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-O?
4043-O has a typical yield strength of 55 MPa (7.98 ksi) and a tensile strength of 145 MPa (21 ksi) — weaker than 94% of aluminum grades. Strength varies by condition: see the 3 listed tempers.
Is 4043-O easy to machine?
Not especially — machinability is rated poor (25/100, worse than 96% 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-O be welded?
Yes — weldability is rated excellent (95/100). Designed as a GMAW/GTAW filler for 6xxx 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-O?
Anodizes dark grey/black because of silicon; weld beads take chemical etch unevenly — paint, powder coat or mechanical finish for appearance parts.
Can 4043-O 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-O?
4043-O 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.
Can FabDigit make parts in 4043-O?
Yes — 4043-O is available for CNC machining and sheet metal with instant online pricing. 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.