Aluminum 4046: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

Alloy 4046 is a member of the 4xxx series of aluminum alloys, which are silicon-bearing alloys primarily used for welding filler and certain wrought applications. The 4xxx series is characterized by silicon as the principal alloying element; in 4046 the Si content is relatively high compared with many other 4xxx alloys, shifting the alloy toward lower melting point and improved fluidity.

Major alloying elements for 4046 are silicon as the dominant alloying addition, with iron and trace amounts of manganese, magnesium, copper, zinc, chromium and titanium as minor constituents. The alloy is essentially non-heat-treatable and derives its mechanical performance from alloy chemistry and mechanical working rather than precipitation hardening.

Key traits of 4046 are excellent molten flow and low hot-cracking tendency (useful in welding and brazing), moderate static strength, good general corrosion resistance typical of aluminum, and reasonable weldability. Formability is fair in the annealed condition but degrades as silicon content increases and as the material is strain-hardened.

Typical industries that use 4046 include automotive and transportation (as filler/weld material and some fabricated components), HVAC and refrigeration (brazed joints and heat-exchanger fabrication), marine (fabrication and joining), and electronics (where fluidity and compatibility for brazing matter). Engineers choose 4046 when excellent filler metal fluidity is required or when a silicon-enhanced alloy gives better joint integrity and resistance to solidification cracking than lower-silicon alloys.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Fully annealed, best for forming and brazing
H14	Medium	Moderate	Fair	Good	Strain-hardened half-hard; used where moderate strength required
H18	High	Low	Poor	Good	Full-hard; limited forming, higher strength via cold work
T4	Not Applicable	Not Applicable	Not Applicable	Not Applicable	Typical T tempers (solution + natural age) are not effective for non-heat-treatable 4046
T6	Not Applicable	Not Applicable	Not Applicable	Not Applicable	Artificial aging does not apply; 4046 is strengthened primarily by work-hardening

Temper significantly alters performance: the annealed (O) condition gives maximum ductility and the best formability for deep draws or tight bends, while H tempers increase strength through cold work at the expense of elongation. Because 4046 is not heat-treatable, conventional T5/T6 sequences do not produce the precipitation strengthening seen in 6xxx or 2xxx series alloys.

Chemical Composition

Element	% Range	Notes
Si	9.0–12.0	Primary alloying element; increases fluidity and reduces melting range
Fe	0.4–1.0	Common impurity; forms intermetallics that can affect ductility
Mn	0.05–0.50	Minor; can help with grain structure and resistance to intergranular corrosion
Mg	0.05–0.30	Low; not a primary strengthening agent in this alloy
Cu	0.05–0.20	Trace; can slightly increase strength but may affect corrosion resistance
Zn	0.05–0.20	Trace; generally limited in 4xxx alloys
Cr	0.05–0.20	Trace; can control grain structure in some product forms
Ti	0.02–0.10	Grain refiner additions for ingot metallurgy or cast/wrought processing
Others (each)	0.05 max	Residual elements including Bi, Pb, Ni etc.

The silicon content dominates microstructural and processing behavior: it lowers the solidus and liquidus temperatures, produces a Si-rich network or particles in the microstructure, and improves melt fluidity for better weld bead appearance and reduced hot cracking. Iron and manganese control the morphology and distribution of intermetallic phases, while minor elements are kept low to avoid deleterious effects on corrosion and ductility.

Mechanical Properties

In service and laboratory tests, 4046 exhibits moderate tensile strength and reasonable ductility in the annealed condition, with tensile strengths increasing as the material is strain-hardened. Yield strength follows the same trend; because the alloy is not precipitation hardenable, cold work (H tempers) is the principal route to raise proof strength. Elongation is high in O condition and drops substantially as hardness increases; full-hard conditions can have very limited elongation and require larger bend radii.

Hardness correlates with temper and cold work; annealed 4046 has low hardness values while H14–H18 conditions show measurable increases consistent with increased yield and tensile values. Fatigue performance is acceptable for non-structural cyclic loads but is sensitive to surface finish and joint quality when used as a filler or weld metal. Thickness effects are present: thin-gauge material is easier to form and cools quickly after welding, while thicker sections can retain coarse microstructures and require different welding parameters.

Property	O/Annealed	Key Temper (H14 / H18)	Notes
Tensile Strength (MPa)	90–130	120–180	Values depend on gauge, product form, and cold work; estimates for typical wrought product
Yield Strength (MPa)	35–70	80–150	Yield rises markedly with strain hardening; no precipitation hardening available
Elongation (%)	20–30	3–12	Elongation falls as temper gets harder; thinning reduces ductility further
Hardness (HB or HV)	25–50 HB	60–95 HB	Hardness increases with H temper; measured values vary with testing standard

Physical Properties

Property	Value	Notes
Density	2.66–2.70 g/cm³	Slightly lower than some Al alloys due to silicon content; typical aluminum density range
Melting Range	~577–615 °C	Eutectic-influenced range due to high Si; lower solidus than pure Al
Thermal Conductivity	110–140 W/m·K	Reduced relative to pure Al; silicon lowers conductivity modestly
Electrical Conductivity	~30–40 %IACS	Alloying reduces conductivity versus commercially-pure aluminum
Specific Heat	~880–910 J/kg·K	Typical for aluminum alloys around room temperature
Thermal Expansion	22–24 µm/m·K (20–100 °C)	Coefficient similar to many aluminum alloys; slight decrease with higher Si

The physical property set makes 4046 suitable for applications where molten fluidity and thermal transfer are important, such as brazing and welding of heat exchangers. The reduced melting range and lower conductivity relative to pure aluminum are trade-offs for improved weldability and jointability in certain fabrication processes.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.2–6.0 mm	Thin sheets are easier to anneal and form	O, H14	Used when forming or as cladding / brazing base material
Plate	6–50 mm	Thicker sections show coarser structure	O, H18	Used in structural or welded assemblies where thickness required
Extrusion	Profiles up to large cross-sections	Cold work during extrusion increases strength	O, H temper after extrusion	Extrudability is fair; silicon content affects die wear
Tube	Various diameters/wall thicknesses	Behavior similar to sheet/pipe of equivalent gauge	O, H tempers	Often used in heat-exchanger and HVAC tubing applications
Bar/Rod	Diameters from a few mm to large	Cold-workable to H tempers	O, H	Commonly supplied as filler wire/rod for welding and brazing; high Si filler rod variants are standard

Processing differences are driven by silicon content: high-Si alloys like 4046 flow well in the liquid state which aids brazing and welding, but the higher Si makes severe cold forming more difficult. Extrusion and rolling require attention to tooling wear and control of cooling to avoid coarse Si particles. Product availability often skews toward filler wire/rod and thin-gauge sheet for joining and heat-exchanger manufacture.

Equivalent Grades

Standard	Grade	Region	Notes
AA	4046	USA	Common wrought designation and basis for filler formulations
EN AW	4046	Europe	Often listed under EN AW-4046 in European catalogs for wrought products
JIS	A4046 (or equivalent)	Japan	Local standards may reference equivalent Al-Si compositions rather than exact numeric match
GB/T	4046	China	Chinese standards include Al-Si alloy variants comparable to AA 4046

Equivalency tables reflect nominal chemistry, but manufacturing routes and impurity limits differ by region and standard. These differences can affect properties such as ductility, intermetallic morphology, and weld filler performance, so designers should verify supplier material certifications and product datasheets when substituting materials across standards.

Corrosion Resistance

4046 exhibits good general atmospheric corrosion resistance typical of aluminum alloys owing to the protective oxide film that forms on aluminum surfaces. Silicon additions do not greatly impair uniform corrosion resistance, but they can modify local electrochemical behavior and the distribution of intermetallic particles, which may create micro-galvanic sites under aggressive chloride-containing environments.

In marine or salt-spray exposure, 4046 performs adequately for many applications but is not as inherently robust as certain high-magnesium alloys that form more tenacious passive films or as well as aluminum-manganese alloys optimized for pitting resistance. Stress corrosion cracking is not a prominent failure mode for 4046 compared with high-strength heat-treatable alloys; however, localized attack at welds and joints can be initiated if surface contaminants or residual stresses are present.

When galvanically coupled to dissimilar metals, 4046 behaves like other aluminum alloys and will be anodic to stainless steel and copper; prudent design with insulating barriers or cathodic protection is required in mixed-metal assemblies. Compared with 5xxx series (Al-Mg) alloys, 4046 offers similar general corrosion performance but trades some ductility and cold-forming capacity for improved welding/filler characteristics.

Fabrication Properties

Weldability

4046 is widely used as a filler/wire for TIG and MIG welding of aluminum and aluminum alloys because its high silicon content reduces the alloy’s solidification range and improves molten flow. TIG and MIG processes with properly selected shielding gases produce clean welds; ER4046 filler wire is commonly recommended for welding Al-Mg and Al-Si base metals when silicon-compatible filler is desired. Hot-cracking risk is reduced with 4046 compared with lower-silicon fillers, but weld parameters must control heat input to avoid excessive porosity and to maintain bead profile.

Machinability

Machinability of 4046 is moderate and influenced by the Si content which increases abrasiveness and tool wear compared with low-silicon alloys. Carbide tooling with positive rake and rigid setups are recommended; cutting speeds should be conservative for large cross-sections and interrupted cuts. Surface finish tends to be good if proper feeds and sharp tools are used, but tool life is shortened and coolant/airblast strategies should be applied to control heat.

Formability

Formability in O temper is good for mild forming operations but becomes poor in H tempers because the silicon-rich microstructure reduces ductility and increases the propensity for cracking on tight bends. Bend radius recommendations should be conservative compared with softer aluminum alloys; for critical forming operations annealing to O is commonly specified prior to forming. For cold stamping and deep drawing, careful process design and possible use of lubrication or hemming techniques are required to compensate for reduced stretchability.

Heat Treatment Behavior

4046 is classified as a non-heat-treatable alloy and therefore does not respond to solution-treatment / artificial aging sequences in the way 6xxx or 2xxx alloys do. Attempts to apply conventional T6-style treatments will not produce the precipitation strengthening typical of those families. Thermal exposure at elevated temperatures will tend to relieve cold work and reduce strength, but it will not produce stable age-hardening.

Annealing to restore ductility is achieved by heating into the typical anneal range for aluminum (commonly in the 300–420 °C range for sufficient time depending on section thickness) and then air-cooling; this returns material to O temper. Strength increases are accomplished through mechanical cold work (H tempers) and are retained until a subsequent anneal or thermal exposure causes recovery and recrystallization.

High-Temperature Performance

Mechanical strength of 4046 falls off gradually with increasing temperature, with appreciable softening occurring above approximately 150–200 °C; long-term strength retention above these temperatures is poor. Oxidation of aluminum is limited to formation of protective oxide at normal service temperatures, but at elevated temperatures the protective nature can be compromised by fluxes or contaminants present during brazing or welding.

Heat-affected zones adjacent to welds may show modified mechanical properties due to thermal cycles and microstructural coarsening; however, because 4046 is not precipitation-hardened, HAZ softening is less dramatic than in heat-treatable alloys but cold-worked parent material can be annealed during welding. For high-temperature structural service, selection of other alloys optimized for creep or elevated-temperature strength is recommended.

Applications

Industry	Example Component	Why 4046 Is Used
Automotive	Weld filler for body and subframes	Excellent weldability and flow, reduced hot cracking
Marine	HVAC/heat-exchanger brazed joints	Good fluidity for brazing and acceptable corrosion resistance
Aerospace	Non-critical fittings, filler material	Good joint integrity and compatibility for aluminum assemblies
Electronics	Heat-exchanger fins and brazed joints	Good thermal transfer and brazing characteristics

4046 is commonly specified where molten flow behavior and joint integrity are critical, particularly in brazing and as welding filler for Al-Mg and Al-Si combinations. It is not typically selected for high-strength primary structures but is highly relevant for joining, repair, and fabrications where weld quality and reduced cracking are priorities.

Selection Insights

Choose 4046 when you need a silicon-rich aluminum alloy for welding or brazing that offers exceptional molten fluidity and reduced solidification cracking. It is especially useful for joining aluminum components where good bead wetting and flow are required, and where excessive hardness is not desired.

Compared with commercially pure aluminum (e.g., 1100), 4046 trades some electrical and thermal conductivity and formability for better strength and dramatically better weld/filler performance. Compared with work-hardened alloys such as 3003 or 5052, 4046 provides similar corrosion behavior but improved molten flow and jointability; it is generally less ductile than those alloys in hard tempers. Compared with heat-treatable alloys like 6061 or 6063, 4046 will not reach the same peak aged strengths, but it is preferred when weldability, low hot-cracking tendency, and brazing compatibility are the overriding criteria.

Closing Summary

Alloy 4046 remains a practical aluminum choice where high silicon content provides superior molten fluidity, weld and brazing performance, and reliable joint formation, making it a staple filler and fabrication alloy in transportation, HVAC, and electronics industries. Designers and fabricators specify 4046 when robust joining characteristics and moderate strength combined with acceptable corrosion resistance are more important than peak age-hardening capability.