4643 Aluminum

Representative aluminum raw/semi-finished material photo; exact grade not verified

4643 Aluminum (AA 4643) is an Al–Si–Mg wrought filler-metal alloy principally supplied as welding wire or rod. Its 3.6–4.6% silicon content provides a lower melting range and good fluidity during welding, while the controlled magnesium addition helps weld deposits develop strength compatible with many 6xxx-series base alloys. Compared with higher-silicon 4043 filler, 4643 is a reduced-silicon, magnesium-containing alternative intended where higher weld strength is important. Product performance must be specified for the actual wire condition and qualified weld deposit, not assumed from sheet or plate properties.

Chemical Composition (wt.%)
Chemical Composition wt.%
Element	Min	Max
Silicon	3.6	4.6
Iron	—	0.80
Copper	—	0.10
Manganese	—	0.05
Magnesium	0.10	0.30
Zinc	—	0.10
Titanium	—	0.15
Beryllium	—	0.0008
Others, each	—	0.05
Others, total	—	0.15
Aluminum	Remainder

Composition notes

Silicon: Registered composition limit.
Iron: Registered composition limit.
Copper: Registered composition limit.
Manganese: Registered composition limit.
Magnesium: Registered composition limit.
Zinc: Registered composition limit.
Titanium: Registered composition limit.
Beryllium: Reported for 4643 aerospace aluminum wire.
Others, each: Registered composition limit.
Others, total: Registered composition limit.
Aluminum: Registered composition balance.

Registered AA 4643 composition limits are in weight percent. Aluminum is the remainder. The supplied registered-composition extract identifies the standard limits for Si, Fe, Cu, Mn, Mg, Zn, Ti, Others Each, and Others Total. A beryllium maximum of 0.0008% is reported by the supplied 4643 wire datasheet; confirm applicable product and purchasing specifications for wire orders.

The reported values apply to AA 4643 alloy/welding-wire material as identified by the cited sources. No tensile or yield strengths are listed because weld-metal properties depend on wire condition, base metal, joint configuration, shielding gas, and welding procedure qualification.

Use the button to switch between Metric and US Customary units.

Table of 4643 Aluminum Properties

Table of 4643 Aluminum Properties
Physical Properties	Metric
Density	2.69 g/cm³2.69 g/cm³
Thermal Properties	Metric
Melting Range	1065–1175 °F
Melting Range	574–635 °C

Test conditions & data notes

Density: Calculated nominal density for active wrought AA 4643.
Melting Range: Reported for 4643 aerospace aluminum wire.
Melting Range: Reported for 4643 aerospace aluminum wire; Celsius conversion corresponds to the cited Fahrenheit range.

Material Conditions & Tempers

AA 4643 is commonly sold as TIG straight wire and MIG spool wire rather than as structural wrought sheet or plate. Wire condition should be ordered to the applicable wire specification; reported commercial offerings include O and strain-hardened H tempers. These condition labels describe the wire, while the final mechanical performance of a welded joint or deposited weld metal requires procedure-specific qualification.

Condition	Description	Notes
O	Annealed or soft wire condition used where maximum ductility and easy handling are needed.	A commercially listed wire temper; no grade-specific strength value is reported in the supplied sources.
H14	Strain-hardened wire condition commercially listed for 4643.	Wire temper only; no grade-specific strength value is reported in the supplied sources.
H16	Higher strain-hardened wire condition commercially listed for 4643.	Wire temper only; no grade-specific strength value is reported in the supplied sources.
H18	Hard strain-hardened wire condition commercially listed for 4643.	Wire temper only; no grade-specific strength value is reported in the supplied sources.

Advantages & Limitations

Advantages	Limitations
The Al–Si composition gives a comparatively low melting range and useful molten-pool fluidity for aluminum welding. Its 0.10–0.30% magnesium addition distinguishes 4643 from 4043-type Al–Si fillers and supports higher-strength weld deposits for suitable 6xxx-series applications. The reduced silicon level relative to 4043 can be useful where weld-metal chemistry and mechanical-property balance favor a lower-Si filler. Low density, approximately 2.69 g/cm³, supports lightweight welded aluminum assemblies. Available in practical wire forms for both TIG straight-wire and MIG spool-fed welding.	4643 is a filler-wire alloy; bulk mechanical properties for unrelated wrought forms must not be substituted for deposited weld-metal or welded-joint properties. Weld strength, ductility, porosity behavior, cracking performance, and corrosion performance depend on the base alloy, dilution, joint preparation, shielding gas, and qualified welding procedure. The alloy is not a high-strength structural 6xxx base metal; it is selected primarily to produce a desired weld-metal composition. Silicon-containing weld deposits may anodize to a different color than adjacent base material, which can matter for decorative anodized assemblies. Use the governing aerospace, AWS, or customer wire specification to control diameter, temper, cleanliness, packaging, and acceptance requirements.

Advantages

Limitations

The Al–Si composition gives a comparatively low melting range and useful molten-pool fluidity for aluminum welding.
Its 0.10–0.30% magnesium addition distinguishes 4643 from 4043-type Al–Si fillers and supports higher-strength weld deposits for suitable 6xxx-series applications.
The reduced silicon level relative to 4043 can be useful where weld-metal chemistry and mechanical-property balance favor a lower-Si filler.
Low density, approximately 2.69 g/cm³, supports lightweight welded aluminum assemblies.
Available in practical wire forms for both TIG straight-wire and MIG spool-fed welding.

4643 is a filler-wire alloy; bulk mechanical properties for unrelated wrought forms must not be substituted for deposited weld-metal or welded-joint properties.
Weld strength, ductility, porosity behavior, cracking performance, and corrosion performance depend on the base alloy, dilution, joint preparation, shielding gas, and qualified welding procedure.
The alloy is not a high-strength structural 6xxx base metal; it is selected primarily to produce a desired weld-metal composition.
Silicon-containing weld deposits may anodize to a different color than adjacent base material, which can matter for decorative anodized assemblies.
Use the governing aerospace, AWS, or customer wire specification to control diameter, temper, cleanliness, packaging, and acceptance requirements.

Processing & Fabrication

Process	Description
GTAW / TIG welding	Use 4643 straight wire where controlled manual or automated deposition is required. Remove oxide, moisture, oil, and other contamination from the wire and joint before welding to limit hydrogen porosity.
GMAW / MIG welding	4643 is available as reel-mounted wire for MIG welding. Establish wire-feed settings, shielding gas, preheat practice, and heat input through procedure qualification for the actual base material and joint.
Weld procedure qualification	Qualify the deposited weld metal and completed joint rather than relying on generic alloy values. Evaluate the required tensile, bend, fatigue, corrosion, and, where applicable, post-weld heat-treatment performance.
Storage and handling	Keep wire clean and dry, protect it from shop contamination, and use appropriate feeding hardware. Aluminum oxide has a much higher melting temperature than the filler, so mechanical and chemical cleaning of the joint is important.

Applications

4643 is used where an Al–Si–Mg filler is needed for aluminum welding, particularly when the objective is stronger weld deposits than conventional high-silicon filler can provide for suitable 6xxx-series assemblies. Selection remains application-specific because weld chemistry is influenced by base-metal dilution and procedure variables.

Aerospace aluminum welding wire: 4643 is commercially identified for aerospace wire supplied to AMS 4189 and is used where controlled filler composition and qualified welding practice are required.
6xxx-series aluminum weldments: The magnesium-containing, reduced-silicon filler chemistry is intended to help obtain weld properties compatible with many 6xxx-series applications.
TIG welding rod: Straight 4643 wire/rod is available in common TIG diameters for precision fabrication and repair work.
MIG welding wire: Reel-mounted 4643 wire supports higher-deposition GMAW production welding when the filler is compatible with the qualified joint.

Standards & Designations

Designation	Value	Description
Aluminum Association	AA 4643	Active registered wrought aluminum-alloy designation; temper is specified separately from the alloy identity.
UNS	UNS A94643	Designation reported for 4643 aerospace aluminum wire.
SAE AMS	AMS 4189	Wire specification designation reported by the supplied 4643 wire source.
AWS	ER4643 (AWS A5.10)	Filler-metal designation reported by the supplied 4643 wire source.
USWC	4189(C)	Designation reported by the supplied 4643 wire source.

Frequently Asked Questions

What is 4643 aluminum primarily used for?

AA 4643 is primarily an aluminum welding filler alloy supplied as wire or rod for TIG and MIG welding. Its Al–Si–Mg chemistry is intended for welds requiring a balance of fluidity, low melting range, and strength compatible with appropriate 6xxx-series applications.

How does 4643 differ from 4043 filler metal?

Both are aluminum–silicon filler alloys, but 4643 has 3.6–4.6% silicon and 0.10–0.30% magnesium. The magnesium addition and lower silicon range distinguish it from 4043 and can favor higher-strength weld deposits when used with a suitable base metal and qualified procedure.

Can published 4643 wire tensile properties be used to design a welded structure?

No. Wire temper properties, if specified, do not establish the mechanical properties of the deposited weld or completed joint. Joint properties depend on base-metal dilution, weld geometry, process, shielding gas, heat input, defects, and any post-weld thermal treatment; use procedure-qualification data for design.

References & Data Notes

(n.d.). Aluminum Association — International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys, December 2025. https://www.aluminum.org/sites/default/files/2026-01/Teal%20Sheets%20December%202025.pdf
(n.d.). ALCOTEC Weld Filler Wire 4643 — Alloy Digest. https://dl.asminternational.org/alloy-digest/article/51/3/Al-324/6484/ALCOTEC-WELD-FILLER-WIRE-4643Silicon-Magnesium
(n.d.). 4643 Aerospace Grade Aluminum Wire. https://www.chalcoaluminum.com/application/aluminum-aerospace/4643-aerospace-aluminum-wire
(n.d.). Aufhauser — Aluminum 4643. https://www.brazing.com/products/Welding_alloys/alloy4643.aspx

Chemical limits and nominal density are taken from the Aluminum Association registered wrought-alloy publication. The melting range and wire-product designations are reported by the cited 4643 wire source. Mechanical-property values are intentionally omitted because the supplied sources do not provide qualified numerical data for a defined 4643 deposited weld metal or welded-joint condition.