Aluminum 4044: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

Alloy 4044 is a member of the 4xxx series aluminum alloys, which are silicon (Si) major-alloying compositions in the wrought family. Its silicon content is high relative to 1xxx–3xxx series alloys and it is classified as a non-heat-treatable alloy relying primarily on solid-solution strengthening and strain hardening for mechanical property gains.

Major alloying constituents are silicon with small controlled additions or limits of iron, manganese and trace elements; copper and magnesium levels are typically very low. The Si-rich composition improves castability and weldability while modifying the alloy's melting behaviour and joining characteristics.

Key traits of 4044 include moderate strength, good corrosion resistance in many atmospheric and mild aqueous environments, excellent weldability and reasonable formability when in the annealed condition. Typical industry uses span automotive body and brazing/filler applications, heat exchangers, electrical components and general structural extrusions where good flow and filler compatibility are important.

Engineers choose 4044 over other alloys when a balance of weldability, brazing performance, and corrosion resistance is needed without the cost, process complexity or reduced ductility that accompany many heat-treatable alloys. Its silicon content improves fluidity and reduces hot-cracking during welding and brazing, which is a primary reason it is selected for joining and filler applications.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Fully annealed, best ductility and formability
H12 / H14 / H16	Moderate	Moderate	Good	Very Good	Strain-hardened tempers; available from light to moderate work hardening
H18 / H24	Higher	Reduced	Fair	Good	Heavier strain-hardening for elevated strength where formability is less critical
T (e.g., T4/T5/T6)	Not applicable / Limited	N/A	Limited	N/A	4xxx alloys are not conventionally heat-treatable; T tempers are rare or related to specific processing

Temper has a strong, predictable effect on 4044 performance because the alloy is non-heat-treatable and derives increased strength primarily from cold work. Moving from O to H‑tempers raises yield and tensile strengths at the expense of ductility and formability, which directly affects bend radii and stretch-forming limits.

For welding and brazing work, annealed (O) material is preferred for forming prior to joining and for minimizing residual stresses in weld zones; H‑tempers are used when higher as‑fabricated strength is required and post-forming operations are limited.

Chemical Composition

Element	% Range	Notes
Si	4.0 – 6.0	Principal alloying element; improves fluidity, reduces melting point range
Fe	≤ 0.7	Common impurity; affects strength and intermetallic formation
Mn	≤ 0.5	Small additions can refine grain structure and improve strength modestly
Mg	≤ 0.20	Typically low; higher Mg not characteristic for 4044
Cu	≤ 0.20	Generally low to minimize corrosion and retain weldability
Zn	≤ 0.10	Low; not a strengthening element here
Cr	≤ 0.10	Trace control element for grain stability
Ti	≤ 0.20	Typically present as grain refiner in some product forms
Others (each)	≤ 0.05	Residuals and trace elements; Al balance

The silicon concentration is the dominant factor controlling 4044 microstructure, solidus-liquidus behaviour and the formation of Si-rich phases. Small iron and manganese contents produce intermetallics that influence high-temperature properties and machinability, while intentionally low Mg and Cu maintain corrosion resistance and weldability. Overall performance is a function of Si-driven solid solution strengthening plus microstructural control via thermo-mechanical processing.

Mechanical Properties

Tensile behaviour for 4044 is typical of non-heat-treatable Al–Si alloys: relatively high ductility in the annealed state and progressively higher yield and tensile strengths with strain hardening. Yield is low in O condition but increases significantly with H‑tempers; elongation is highest in O and drops as the material is work-hardened. Hardness follows the same trend; H‑tempers exhibit higher hardness due to dislocation accumulation and possible fine precipitation of impurity phases.

Fatigue performance is moderate and strongly dependent on surface finish, thickness and residual stress state induced by forming or welding. Thinner gauge material tends to show reduced fatigue life if not properly deburred and stress relieved; weld heat-affected zones and inclusions from processing can be nucleation sites for fatigue cracks. Designers must account for gauge-dependent behavior and the influence of welds or brazed joints on cyclic life.

Microstructural heterogeneities from casting or extrusion, such as Si particle distribution, affect machinability and wear resistance; thicker sections can retain coarser Si particles and reduced ductility compared with thin sheet produced and cold-rolled to H‑tempers.

Property	O/Annealed	Key Temper (e.g., H14)	Notes
Tensile Strength	70 – 110 MPa (typical)	130 – 180 MPa (typical)	Values vary by temper and thickness; H‑tempers substantially higher
Yield Strength	30 – 60 MPa (typical)	100 – 150 MPa (typical)	Yield rises sharply with cold work
Elongation	20 – 35%	5 – 15%	Ductility reduced by strain hardening
Hardness (HB)	25 – 40 HB	55 – 75 HB	Brinell as a comparative index, varies with work hardening

Physical Properties

Property	Value	Notes
Density	2.70 g/cm³	Typical for Al alloys; useful for mass and stiffness calculations
Melting Range	≈ 577 – 635 °C	Eutectic-influenced melting due to Si content; exact range depends on Si level
Thermal Conductivity	≈ 120 – 160 W/m·K	Lower than pure Al; Si and impurities reduce conductivity
Electrical Conductivity	≈ 35 – 55 % IACS	Alloying reduces conductivity compared with 1xxx series
Specific Heat	≈ 880 – 910 J/kg·K	Typical for aluminum alloys at ambient temperatures
Thermal Expansion	≈ 23 – 24 ×10⁻⁶ /K	Similar to other Al alloys, important for thermal mismatch design

The physical properties make 4044 suitable where good thermal conductivity is desirable but absolute electrical conductivity is not critical. Thermal expansion and conductivity figures are important when designing heat exchangers, electronic housings or multi-material assemblies to manage differential expansion. The relatively low melting onset due to Si eutectics also governs welding, brazing and casting/joining process windows.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.3 – 6.0 mm	Uniform; responsive to cold work	O, H14, H24	Used for panels, heat sinks, brazing sheets
Plate	6 – 25 mm	Slightly lower cold-work response	O, H18	Heavier gauge, coarse Si distribution may reduce ductility
Extrusion	Profiles up to several meters	Good directional strength	O, H14	Si aids flow and surface finish in extrusion dies
Tube	Various OD/wall combinations	Similar to sheet behavior	O, H14	Used for brazed heat exchangers and structural tubing
Bar/Rod	Diameters up to ~100 mm	Higher as-extruded strength	O, H12	Often used where machining or forging follows

Processing differences between sheet, extrusion and plate are controlled by cooling rates and working schedules that affect Si particle distribution and grain size. Thin-gauge products cold-rolled to H‑tempers exhibit higher strength and lower elongation than annealed plate. Extruded shapes exploit Si-induced fluidity to produce complex thin-wall sections while preserving surface finish and dimensional stability for downstream forming or joining.

Equivalent Grades

Standard	Grade	Region	Notes
AA	4044	USA	Aluminum Association designation
EN AW	4044	Europe	Common European designation; compositional limits may differ slightly
JIS	A4044 (approx.)	Japan	Local standards may use similar Al–Si designations
GB/T	Al4044 (approx.)	China	Chinese standards may list Al–Si alloys with comparable Si content

Equivalent grade labels generally denote broadly similar chemistry, but regional standards can differ in the allowable ranges for impurities and trace elements. These tolerances affect properties such as electrical conductivity, machinability and brazing performance; engineers should consult specific standard tables for final procurement and qualification. When replacing or substituting, verify certification test reports for critical properties like Si content, tensile data and impact of any additional alloying.

Corrosion Resistance

4044 exhibits good general atmospheric corrosion resistance comparable to many commercial Al alloys, owing to the protective Al2O3 film that naturally forms on aluminum surfaces. Silicon additions do not substantially degrade the passive film, and 4044 performs well in industrial and rural atmospheres where pollutants are moderate.

In marine environments the alloy shows reasonable resistance to uniform corrosion, but localized corrosion can occur in crevices and stagnant seawater if galvanic coupling with more noble materials (e.g., stainless steel or copper alloys) is present. Surface preparation, coatings and cathodic/anodic considerations are necessary for long-term service in harsh marine exposures.

Stress corrosion cracking susceptibility for 4044 is low relative to high-strength, heat-treatable 2xxx and 7xxx series alloys because its strength levels are moderate and silicon does not promote the same intergranular attack mechanisms. Nonetheless, welded or brazed joints must be detailed carefully, as heterogeneous microstructures and tensile residual stresses can accelerate local corrosion processes compared with base metal.

Fabrication Properties

Weldability

4044 is highly weldable and is often used as a filler chemistry for aluminum welding and brazing because the silicon improves fluidity and reduces hot‑cracking tendency. Common processes such as GMAW (MIG) and GTAW (TIG) perform well when appropriate filler (ER4043/ER4044) wires are selected; ER4044 is widely used for automotive and brazing applications. The heat-affected zone may show localized softening in highly worked tempers, and preheating or post-weld treatments are sometimes used to reduce residual stresses.

Machinability

Machinability of 4044 is moderate; silicon particles increase tool engagement stability and can improve chip control relative to pure Al while also increasing tool wear versus very soft alloys. Carbide tooling with TiN or TiAlN coatings and positive rake geometries are recommended for stable cutting at moderate speeds. Surface finish is good when chips are evacuated cleanly; built-up edge formation is less problematic than in some copper-bearing alloys.

Formability

Formability is excellent in the O condition, enabling tight bend radii and deep drawing applications when Si particle distribution and grain size are controlled. Work hardening reduces formability in H‑tempers, so forming operations are typically performed in annealed condition followed by (if needed) strain-hardening to reach the required strength. Minimum recommended inside bend radii depend on gauge and temper but are best determined empirically for a given tool set and alloy coil batch.

Heat Treatment Behavior

4044 is classified as a non-heat-treatable alloy; its mechanical properties cannot be improved by conventional solution treatment and artificial aging the way 6xxx or 7xxx families are. The primary strengthening route is cold work (strain hardening) combined with solid-solution effects from silicon. Attempts to apply T‑type treatments have limited benefit and are mainly related to specific product processing rather than strengthening cycles.

Annealing and recrystallization are effective for restoring ductility: full anneal (O) dissolves work-induced dislocation structures and coarsens any fine precipitates or Si dispersoids to produce the best forming characteristics. Stabilization and stress-relief cycles are used industrially to control residual stresses after welding, brazing or forming rather than to raise strength.

High-Temperature Performance

Strength for 4044 degrades with increasing temperature, with usable structural behavior generally limited to temperatures below ~150 °C for sustained loads. Above this range, dislocation mobility increases and the contribution of solid solution and work hardening to strength diminishes rapidly, so designers should restrict continuous operation to lower temperatures or use thicker sections to compensate.

Oxidation is not severe for aluminum alloys at moderate elevated temperatures because the Al2O3 scale is protective, but prolonged exposure at high temperatures accelerates growth of oxide and diffusion-driven microstructural coarsening of Si phases. Welding and brazed joints exposed to elevated service temperatures may experience softening in the HAZ and should be evaluated for creep or stress relaxation where cyclic loading or sustained stresses exist.

Applications

Industry	Example Component	Why 4044 Is Used
Automotive	Brazing filler and heat exchanger fins	Excellent fluidity and weld/braze compatibility; corrosion resistance
Marine	HVAC ducting and non-critical structural components	Corrosion resistance and ease of fabrication
Aerospace	Non