4943 Aluminum

Representative aluminum material photo; exact grade not verified

4943 Aluminum (AA 4943) is an active registered Al–Si–Mg alloy chiefly supplied as solid welding wire or rod, including ER4943 and R4943 filler metal. Its 5.0–6.0% silicon content provides a low-melting, fluid weld pool similar to 4043, while magnesium supports a stronger weld deposit and post-weld heat-treatment response. It is used for welding many 1xxx, 3xxx, 5xxx alloys containing less than 2.5% Mg, and 6xxx-series alloys. Published mechanical values below apply specifically to deposited weld metal in the as-welded condition, not to a generic wrought-product temper.

Chemical Composition (wt.%)
Chemical Composition wt.%
Element	Min	Max
Silicon	5.0	6.0
Iron	—	0.40
Copper	—	0.10
Manganese	—	0.05
Magnesium	0.10	0.50
Zinc	—	0.10
Titanium	—	0.15
Beryllium	—	0.0003
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 AA 4943 composition limit.
Zinc: Registered composition limit.
Titanium: Registered composition limit.
Beryllium: Reported by Hobart as below 0.0003% for ER4943/R4943 weld-metal chemistry; not shown as a registered AA 4943 limit in the supplied register excerpt.
Others, each: Registered composition limit.
Others, total: Registered composition limit.
Aluminum: Registered balance.

Registered Aluminum Association limits are shown for AA 4943. Aluminum is the remainder. Hobart’s ER4943/R4943 product data separately report beryllium below 0.0003% in weld-metal chemistry; this is retained as a filler-product datum rather than presented as an Aluminum Association registered limit. The Hobart product sheet lists a 0.30–0.50% Mg AWS filler-metal specification range, whereas the registered AA 4943 range is 0.10–0.50% Mg.

Values are source-reported for AA 4943 or ER4943/R4943 deposited weld metal. Tensile strength and the melting range are for Hobart Maxal 4943 filler metal; they must not be used as design values for an unspecified 4943 wrought-product form or temper.

Table of 4943 Aluminum Properties

Table of 4943 Aluminum Properties
Physical Properties	Metric
Density (calculated nominal)	2.68 × 10³ kg/m³
Density (ER4943/R4943 filler product)	0.097; 2.685 lb/in³; g/cm³
Mechanical Properties	Metric
Tensile Strength (as-welded deposited weld metal)	33,000; 228 psi; MPa
Thermal Properties	Metric
Melting Range (ER4943/R4943 filler product)	1065–1175; 575–635 °F; °C
Electrical Properties	Metric
Electrical Conductivity (ER4943/R4943 filler product)	41 % IACS

Test conditions & data notes

Density (calculated nominal): Active wrought alloy designation; Aluminum Association calculated nominal density.
Density (ER4943/R4943 filler product): Hobart Maxal 4943 typical physical property.
Tensile Strength (as-welded deposited weld metal): Typical ER4943/R4943 weld-metal result; Hobart states tests were welded and tested in accordance with AWS A5.10.
Melting Range (ER4943/R4943 filler product): Hobart Maxal 4943 typical physical property.
Electrical Conductivity (ER4943/R4943 filler product): Hobart Maxal 4943 typical physical property.

Material Conditions & Tempers

4943 is commonly marketed as ER4943 wire and R4943 rod rather than as a conventional sheet, plate, or extrusion temper. The supplied product data provide an as-welded deposited-metal tensile result. Heat treatment after welding may be used where the joint and base-metal heat-treatment practice permit it, but no standalone wrought-temper property table was supplied.

As-welded deposited weld metal: ER4943/R4943 weld deposit tested in accordance with the supplier’s AWS A5.10-referenced procedure. This is a typical weld-metal value, not a minimum strength for every joint configuration or an AA 4943 wrought temper.

Advantages & Limitations

Advantages	Limitations
The Al–Si–Mg chemistry gives 4943 a lower melting range and high fluidity, supporting a smooth weld pool and good wetting behavior. Compared with conventional 4043-type filler use, 4943 is intended to provide a stronger deposited weld metal without relying on base-metal dilution. It is suitable for post-weld heat-treatment-and-aging applications when the complete assembly and welding procedure are designed for that route. The supplier identifies low shrinkage, reduced distortion, low welding smut/discoloration, and low hot-cracking sensitivity in most applications. The 5–6% Si range retains the familiar welding characteristics that make 4xxx filler metals practical for many 6xxx fabrication joints.	4943 is principally a welding consumable; its deposited-metal properties do not establish structural design allowables for a wrought 4943 product. Filler selection must consider base-alloy chemistry, restraint, service environment, joint design, and required post-weld properties; it is not a universal replacement for 5xxx filler metals. The stated suitability for 5xxx alloys is limited by the supplier to alloys containing less than 2.5% Mg; higher-magnesium alloys require careful filler selection. As with other aluminum welds, welding locally changes the heat-affected-zone temper of heat-treatable base materials. The filler’s grey anodized color may not match the visual finish required for cosmetic anodized assemblies.

Advantages

Limitations

The Al–Si–Mg chemistry gives 4943 a lower melting range and high fluidity, supporting a smooth weld pool and good wetting behavior.
Compared with conventional 4043-type filler use, 4943 is intended to provide a stronger deposited weld metal without relying on base-metal dilution.
It is suitable for post-weld heat-treatment-and-aging applications when the complete assembly and welding procedure are designed for that route.
The supplier identifies low shrinkage, reduced distortion, low welding smut/discoloration, and low hot-cracking sensitivity in most applications.
The 5–6% Si range retains the familiar welding characteristics that make 4xxx filler metals practical for many 6xxx fabrication joints.

4943 is principally a welding consumable; its deposited-metal properties do not establish structural design allowables for a wrought 4943 product.
Filler selection must consider base-alloy chemistry, restraint, service environment, joint design, and required post-weld properties; it is not a universal replacement for 5xxx filler metals.
The stated suitability for 5xxx alloys is limited by the supplier to alloys containing less than 2.5% Mg; higher-magnesium alloys require careful filler selection.
As with other aluminum welds, welding locally changes the heat-affected-zone temper of heat-treatable base materials.
The filler’s grey anodized color may not match the visual finish required for cosmetic anodized assemblies.

Processing & Fabrication

Process	Description
GMAW (MIG)	Hobart specifies direct-current electrode positive (DCEP) for GMAW. Use 100% argon or argon/helium shielding mixtures; the cited typical GMAW gas-flow range is 35–50 cfh (14–24 L/min). Clean oxide and contamination from the joint before welding.
GTAW (TIG)	Hobart specifies AC for GTAW with 100% argon or argon/helium mixtures; the cited typical GTAW gas-flow range is 20–30 cfh (10–14 L/min). ER4943 is available as wire and R4943 as rod.
Preheat and interpass control	Control cleaning, oxide removal, preheat, and interpass temperature as required by the base-metal type and thickness. The supplier notes that these procedure variables can be critical for aluminum welding.
Post-weld heat treatment	4943 is intended for applications requiring post-weld heat treatment and aging. Establish the thermal cycle from the base-material specification and qualified welding procedure; do not assume that an as-welded deposit retains the properties of a heat-treated base alloy.

Applications

4943 is selected where 4043-like weldability is desired but a stronger, potentially heat-treatable weld deposit is beneficial. Typical use is in aluminum fabrication rather than as a general-purpose wrought construction alloy.

6xxx-series structural and fabricated components: The alloy is intended for welding 6xxx base metals, combining fluid Al–Si filler behavior with higher typical deposited-metal tensile strength than conventional 4043-type practice.
Post-weld heat-treated assemblies: 4943 is specifically promoted for weldments that will be solution heat treated and aged after welding, subject to a qualified assembly-level process.
Automotive and motorcycle frames: The supplier lists automotive/motorcycle frames, where weld-pool fluidity, reduced distortion, and the opportunity for post-weld heat treatment can be useful.
Selected 1xxx, 3xxx, and low-magnesium 5xxx fabrications: Hobart identifies these base-metal families, including 5052 as an example, for 5xxx alloys containing less than 2.5% Mg.
Aerospace hardware: The supplier lists aerospace hardware; application remains dependent on the applicable engineering approval, filler specification, and qualified welding procedure.

Standards & Designations

Designation	Value	Description
Aluminum Association	4943	Active registered wrought aluminum alloy designation; registered chemical-composition limits are published in the Aluminum Association Teal Sheets.
AWS	AWS A5.10 ER4943, R4943	Hobart Maxal 4943 solid wire and rod are listed as conforming to these filler-metal classifications.
ASME	SFA 5.10 ER4943, R4943	Listed by the Hobart product data as a conformance.
EN ISO	EN ISO 18273-S Al 4943 (AlSi5Mg)	Listed by Hobart as a DB designation for the product.
ASME Boiler and Pressure Vessel Code	F23 filler-metal group	The American Welding Society article states that 4943 has been designated as a Group F23 filler metal by ASME Boiler and Pressure Vessel Code.

Frequently Asked Questions

How does 4943 differ from 4043 aluminum filler metal?

Both are Al–Si fillers with similar fluid weld-pool behavior, but 4943 also contains magnesium. This supports a higher-strength deposited weld metal and makes 4943 suitable for post-weld heat-treatment-and-aging applications when the full joint procedure is qualified.

What tensile strength can be expected from 4943 weld metal?

Hobart reports a typical as-welded tensile strength of 33,000 psi (228 MPa) for its ER4943/R4943 weld metal. Actual joint strength depends on base metal, joint geometry, dilution, shielding, welding parameters, and any post-weld thermal treatment.

Can 4943 be used to weld 5052?

The Hobart data list 5xxx base metals containing less than 2.5% magnesium, with 5052 given as an example. Filler choice should still be verified against the specific service environment and corrosion, ductility, and strength requirements of the weldment.

References & Data Notes

(n.d.). Aluminum Association, International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys (Teal Sheets), revised December 2025. https://www.aluminum.org/sites/default/files/2026-01/Teal%20Sheets%20December%202025.pdf
(n.d.). Hobart Maxal 4943 product datasheet. https://www.hobartbrothers.com/wp-content/uploads/hobart-catalog/datasheets/Hobart_Maxal_4943-1.pdf
(n.d.). American Welding Society, Filler Metal 4943: A Fresh Beginning in Welding. https://www.aws.org/magazines-and-media/welding-journal/4943-filler-metal-a-fresh-beginning

Chemical limits are registered AA 4943 values unless explicitly noted otherwise. Numerical mechanical and filler physical data are typical supplier data for ER4943/R4943 deposited weld metal or filler product, not guaranteed values or generalized wrought-alloy properties.