Aluminum 3009: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

3009 is an alloy in the 3xxx aluminum series, a family defined by manganese as the principal alloying element. As a member of the 3xxx group, 3009 derives its basic strengthening from solid-solution effects and work-hardening rather than precipitation heat treatment, which governs its processing and performance limits.

The major alloying constituents in 3009 are manganese (Mn) with minor magnesium (Mg) additions and trace levels of silicon, iron and other residuals. These alloying additions yield a combination of improved strength over commercially pure aluminum, good formability, and respectable corrosion resistance without the need for age hardening cycles.

Key traits of 3009 include moderate tensile and yield strength for a non-heat-treatable alloy, good resistance to atmospheric corrosion, excellent cold formability in softened tempers, and routine weldability using common fusion processes. Typical industries using 3009 include packaging and containers (sheet for cans and closures), building and cladding, HVAC components, and general sheet metal applications where a balance of formability and strength is required.

Engineers often choose 3009 where formability and reasonable strength at low cost are priorities and where precipitation-hardening alloys are unnecessary or undesirable. Its position in the 3xxx family gives it a cost and corrosion advantage over higher-strength heat-treatable alloys for many sheet and light-structure components.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High (~25–40%)	Excellent	Excellent	Fully annealed condition for maximum ductility
H12 / H14	Low–Medium	Moderate (~12–25%)	Very good	Very good	Light cold work increases yield, common for formed parts
H18	Medium–High	Low (~2–6%)	Poor	Good	Full-hard, used when springback and stiffness are required
H32 / H34	Medium	Moderate (~8–18%)	Good	Good	Strain-hardened and partially annealed for balance of formability and strength
H111	Low–Medium	Moderate (~10–20%)	Very good	Very good	Essentially stable for limited forming operations
T5 / T6 / T651	Not applicable	N/A	N/A	N/A	Typical precipitation tempers are not applicable; 3009 is non-heat-treatable

Temper choice controls the mechanical balance of 3009 explicitly through work-hardening and annealing cycles. Annealed (O) tempers permit deep drawing and complex forming while H‑tempers are selected to achieve higher yield and stiffness at the expense of elongation and formability.

Because 3009 is not responsive to precipitation hardening, temper control is achieved entirely by mechanical cold work and controlled annealing steps, which also influence springback, residual stresses and subsequent weld/paint behavior.

Chemical Composition

Element	% Range	Notes
Si	0.20–0.60	Typical impurity level; higher Si reduces ductility slightly
Fe	0.20–0.70	Common impurity; excessive Fe can reduce corrosion resistance and formability
Mn	0.60–1.50	Principal strengthening element for 3xxx series; improves strength and recrystallization behavior
Mg	0.10–0.50	Small Mg raises strength modestly and can improve strain hardening response
Cu	≤0.10	Kept low to maintain corrosion resistance and minimize SCC susceptibility
Zn	≤0.10	Controlled low levels to avoid detriment to corrosion resistance
Cr	≤0.10	Trace levels may be present to stabilize grain structure
Ti	≤0.15	Microalloying for grain refinement in cast or wrought processing
Others (each)	≤0.05	Unspecified residuals, balancing to Aluminum (~remainder)

The manganese content is the dominant purposeful alloying addition and sets the 3xxx series behavior by providing solid-solution strengthening and stable substructure during cold work. Minor magnesium additions raise strength and modify strain-hardening behavior, while limiting copper and zinc keeps general corrosion resistance good.

Trace elements and residuals influence processing window, recrystallization, and surface properties; material certified to a given specification will control these to ensure consistent forming, joining and corrosion performance.

Mechanical Properties

Tensile behavior of 3009 is characteristic of non-heat-treatable Al–Mn alloys: moderate ultimate tensile strength with a relatively low yield point in annealed condition and rising yield as the material is cold-worked. Ductility is high in O temper and reduces progressively with increased strain hardening; thus designers must account for reduced allowable strain for H‑tempers during forming operations.

Yield and tensile strength both depend strongly on temper and thickness. Thin-gauge sheet work-hardened to H14/H18 will exhibit substantial increases in yield compared with O condition, but this is coupled with reduced elongation and increased springback, which affects forming dies and dimensional tolerance control.

Hardness correlates with temper: Vickers/BHN values move from low in O (soft, low hardness) to significantly higher values in H18 (full hard). Fatigue performance is generally favorable for light-duty cyclic loading but is sensitive to surface finish, residual stresses from forming and welding, and thickness-driven constraint effects.

Property	O/Annealed	Key Temper (e.g., H14/H18)	Notes
Tensile Strength	~70–120 MPa	~150–260 MPa	Wide range due to temper and thickness; values approximate for typical sheet gauges
Yield Strength	~30–60 MPa	~120–220 MPa	Work hardening dramatically raises yield; yield-to-tensile ratio improves with cold work
Elongation	~25–40%	~2–20%	Ductility decreases with strain hardening; design for forming in O or light-hardened tempers
Hardness (BHN)	~20–40 HB	~40–90 HB	Hardness roughly proportional to previous cold work; influences wear and embossing performance

Physical Properties

Property	Value	Notes
Density	2.70 g/cm³	Typical for Al–Mn wrought alloys, useful for mass and stiffness calculations
Melting Range	600–655 °C	Alloying depresses solidus slightly from pure Al (660 °C); cast-related phases not significant in wrought sheet
Thermal Conductivity	~130–170 W/m·K	Lower than pure Al but still high; useful for heat-dissipation components
Electrical Conductivity	~30–40 % IACS	Reduced from commercial-purity aluminum due to alloying; adequate for some busbar and connector uses where formability needed
Specific Heat	~900 J/kg·K	Typical specific heat near room temperature for aluminum alloys
Thermal Expansion	23–24 µm/m·K (20–100 °C)	Similar to other Al alloys; important for thermal joining and bimetallic design considerations

3009 retains many of aluminum's attractive physical attributes: low density, high thermal conductivity and large specific heat. These factors contribute to favorable strength-to-weight and thermal management in sheet applications.

For designers, the moderate reduction in electrical and thermal conductivity relative to purer alloys should be weighed against the alloy’s improved mechanical properties and formability advantages.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.2–6.0 mm	Thickness affects work-hardening rate; thin gauges respond well to can forming	O, H12, H14, H18	Dominant form for packaging, cladding and formed parts
Plate	6–25 mm	Reduced cold formability; more limited to machined parts and structural uses	O, H32	Used where thicker sections or machining are required
Extrusion	Variable cross-sections	Section geometry influences residual stresses; cold working post-extrusion commonly used	O, H111	Less common than sheet, used for specialty profiles
Tube	0.3–5 mm wall	Drawing and seam welding behavior influenced by temper; thin walls require O/H14	O, H14	HVAC ducting and light structural tubing
Bar/Rod	Ø6–50 mm	Used for machined components and fittings; bar stock usually softer for secondary operations	O, H111	Less common for 3009; other series more typical for high-strength bars

Processing differences between sheet, plate and extrusions revolve around strain path, recrystallization during heating and the ability to cold-work for strengthening. Sheet gauges are optimized for deep drawing and roll-forming, while thicker plate and bar forms are more oriented to machining and limited forming.

Availability of specific tempers depends on mill capabilities and market demand; 3009 is most commonly stocked as sheet in a range of O and H tempers for forming and can manufacturing.

Equivalent Grades

Standard	Grade	Region	Notes
AA	3009	USA	Typical wrought alloy designation under Aluminum Association standards
EN AW	3009	Europe	EN designation commonly written as EN AW‑3009 for equivalent composition control
JIS	A3009 / A3000 series	Japan	Japanese standards map to 3xxx family; exact suffix may vary with spec
GB/T	3009 / AlMn series	China	Chinese GB/T tables list comparable Al–Mn wrought alloys; verify exact spec for critical use

Regional standards often use a direct numeric carry-over for wrought Al–Mn alloys, but chemical limits, permitted impurities and temper definitions can differ. For critical parts it is important to compare the specific standard sheet or mill certificate for compositional and mechanical tolerances rather than assuming interchangeability.

Subtle differences such as maximum iron or silicon limits, guaranteed mechanical properties at given thicknesses, and finish specifications can affect corrosion and forming behavior and thus require validation for cross-standard substitutions.

Corrosion Resistance

In atmospheric environments 3009 exhibits good natural corrosion resistance comparable to other Al–Mn alloys due to the protective aluminum oxide film. It performs well in industrial and rural atmospheres and resists staining and general pitting better than copper-bearing alloys because of its low copper content.

In marine or chloride-containing environments, 3009 offers moderate resistance; localized pitting is possible on exposed edges or if the protective film is mechanically damaged. For prolonged marine exposure, 5xxx (Al–Mg) series alloys generally provide superior performance, though 3009 remains acceptable for interior marine components and applications not directly exposed to seawater spray.

Stress corrosion cracking risk for 3009 is low owing to its low strength in typical tempers and absence of high copper; however, welded structures with high residual tensile stresses and aggressive environments should be evaluated. Galvanic interactions follow standard aluminum rules: 3009 will corrode preferentially when coupled with more noble metals like copper or stainless steel unless electrically isolated or sacrificial anodes are applied.

Compared with heat-treatable families (6xxx/7xxx), 3009 trades peak strength for more stable corrosion performance in many atmospheric applications and avoids post-heat-treatment temper instability issues.

Fabrication Properties

Weldability

3009 is readily welded by common fusion processes such as GTAW (TIG) and GMAW (MIG) with good wetting and low hot-cracking propensity. Use of standard aluminum filler alloys such as ER4043 (Al‑Si) or ER5356 (Al‑Mg) is common depending on desired ductility and corrosion resistance; ER4043 offers improved fluidity and reduced hot-cracking risk in thin sheet welding.

Heat-affected zone (HAZ) softening is limited compared to heat-treatable alloys because 3009 is not age hardened, but local residual stresses and distortion can occur with heavy weld lines and thin gauges. Pre- and post-weld mechanical treatments (stress relief bending, light tempering or mechanical straightening) may be necessary for precision assemblies.

Machinability

As a relatively soft, ductile wrought alloy, 3009 machines with moderate ease but will tend to produce long, continuous chips if not using chip-break geometry. Carbide tooling with positive rake angles and high feed rates is recommended to avoid built-up edge; conservative cutting speeds relative to steel and titanium should be used to account for aluminum’s tendency to clog and stick.

Machinability index is lower than free‑cutting aluminum alloys but comparable to other 3xxx series alloys; surface finish and dimensional control are usually excellent if proper coolant, tool coating and chip evacuation are maintained.

Formability

3009 is highly formable in O and mild H tempers, allowing deep drawing, ironing and complex stamping operations with relatively low risk of cracking. Minimum recommended bend radii depend on temper and thickness but are generally in the range of 1–3× material thickness for air bending in softened tempers and increase for harder tempers.

Work hardening response is predictable and uniform; designers should plan forming sequences to avoid overstrain in localized regions and may use intermediate anneals to restore ductility when multiple forming stages are required.

Heat Treatment Behavior

3009 is a non-heat-treatable wrought alloy; its mechanical property envelope is controlled by cold working and annealing rather than solution treatment and precipitation aging. As such, conventional solution/aging cycles used for 6xxx or 7xxx series do not produce significant hardening in 3009.

Soft annealing (recrystallization anneal) is used to restore ductility after cold work and is typically performed at temperatures that promote recrystallization without incipient melting or excessive grain growth. Controlled furnace annealing and subsequent quenching are followed by mechanical processing to reach required H‑tempers.

Because hardening is achieved through plastic deformation, designers can tailor local properties using mechanical processes (e.g., cold rolling, stretch forming) and localized anneals; this makes 3009 versatile for parts requiring variable stiffness or spring characteristics without complex heat-treatment infrastructure.

High-Temperature Performance

3009 retains modest strength up to moderately elevated temperatures but exhibits progressive softening above ~150–200 °C, which limits structural applications at sustained higher temperatures. Design service temperature for long-term load-bearing components is typically kept below 100–150 °C to preserve yield margins and fatigue life.

Oxidation rates at elevated temperature remain low due to aluminum’s protective oxide, but surface scale and potential embrittlement of surface films can alter formability after prolonged exposure. Weld HAZ and joint regions exposed to higher temperatures will show local softening and should be considered in thermal cycling and creep-critical designs.

Applications

Industry	Example Component	Why 3009 Is Used
Automotive	Outer body panels, trim	Good formability and dent resistance with low weight
Packaging	Beverage can bodies, closures	Balance of drawability, surface finish and cost
Building & Construction	Cladding, soffits, gutters	Corrosion resistance and ease of forming for architectural details
HVAC	Ductwork, fins	Thermal conductivity, formability and corrosion resistance
Consumer Appliances	Inner panels, housings	Cost-effective, easy to stitch-weld or rivet with good surface finish

3009's combination of formability, adequate strength and corrosion resistance makes it a go-to alloy for thin-gauge sheet applications where complex forming and low weight are required. Its use in packaging and light architectural products remains predominant because of the alloy’s balance of properties and mill availability.

Selection Insights

Choose 3009 when high formability and reasonable strength are the primary drivers and when precipitation hardening is unnecessary. The alloy offers a lower-cost, easily formed alternative to many heat-treatable alloys and provides better corrosion performance than copper-bearing alloys.

Compared with commercially pure aluminum (1100), 3009 trades some electrical and thermal conductivity for improved yield and tensile strength and better strain-hardening capability, making it preferable for load-bearing formed parts. Versus common work-hardened alloys such as 3003 or 5052, 3009 typically sits between them: providing slightly higher strength than pure Al and competitive formability, while offering corrosion resistance comparable to 3003 but typically inferior to the higher-Mg 5052 in marine environments.

When compared with heat‑treatable alloys (6061/6063), 3009 is selected where complex forming, lower cost and better general corrosion resistance are more important than achieving maximum peak strength; it is the right choice for deep-drawn and spun components where post-form heat treatments would be impractical or damaging to geometry.

Closing Summary

3009 remains a relevant engineering alloy because it combines the manufacturability and corrosion stability of the 3xxx series with modest strength increases from controlled Mn and Mg additions. Its compatibility with standard forming, joining and finishing processes makes it a practical choice for sheet-dominated industries where cost-effective, high-ductility materials are required.