Aluminum A3004: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

A3004 is a member of the 3xxx series aluminum alloys, falling into the Al-Mn family where manganese is the principal alloying addition. It is a non-heat-treatable, strain-hardenable alloy that often contains modest copper and silicon additions to boost strength over the baseline 3003 family. Its strengthening mechanism is predominantly cold work (strain hardening) and microalloying-driven solid solution and dispersoid effects rather than precipitation hardening. Typical performance characteristics include moderate to high ductility in annealed condition, improved room-temperature strength in strain-hardened tempers, good general corrosion resistance, and conventional aluminum weldability and formability.

A3004 is selected by industries that require a balance of formability and higher cold-work strength than pure or lightly alloyed Al-Mn grades. Common sectors include architectural cladding, heat exchanger fins, cookware and consumer appliances, transportation panels, and general sheet metal work where stamping and drawing are required. It is chosen over simpler alloys when the design requires additional yield and tensile strength without sacrificing forming operations or when surface quality and paintability are important. Engineers prefer A3004 when a cost-efficient, readily formed alloy with better strength than 1100/3003 but without the processing penalties of heat-treatable alloys is needed.

The alloy is widely available in sheet, coil, and some extruded forms, making it practical for high-volume manufacturing. Production reasons such as ease of cold work, predictable springback, and stable temper transitions during processing add to its attractiveness for designers and production engineers. Material selection typically hinges on the balance of part geometry, forming routes, and required post-forming strength levels.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Fully annealed condition for maximum ductility
H14	Medium	Moderate	Very good	Very good	Half-hard, common for moderate forming and moderate strength
H18	High	Low	Fair	Very good	Full-hard, used for applications needing higher strength and stiffness
H24	Medium-High	Moderate	Good	Very good	Quarter-soft (strain-hardened then stabilized), balance of form/final strength
H26	High	Low-Moderate	Fair	Very good	Temper with greater work-hardening for higher yield

Tempers in the 3xxx family directly control the trade-off between strength and formability through the degree of cold work. Annealed (O) provides the best drawability and elongation, while H-tempers progressively increase yield and tensile strength at the expense of ductility and deep-draw capability.

Manufacturers will commonly sequence anneal, preforming, and final cold work to achieve tailored property stacks on parts. Stabilized H-tempers (e.g., H24) are often used where mild springback control and subsequent moderate forming stages are required.

Chemical Composition

Element	% Range	Notes
Si	0.3 max	Minor deoxidizer; small amounts improve castability and surface finish
Fe	0.7 max	Typical impurity; influences grain structure and can reduce ductility if excessive
Mn	1.0–1.5	Principal strengthener in 3xxx series; improves strain-hardening response
Mg	0.10 max	Typically low; larger amounts shift behavior toward 5xxx family
Cu	0.2–0.6	Small Cu raises strength and tensile properties compared with 3003
Zn	0.25 max	Minor impurity; modest effect on strength
Cr	0.10 max	Trace addition to control grain structure and improve temper stability
Ti	0.15 max	Grain refiner in cast products and ingots
Others (incl. Zr, Be)	0.05 each, 0.15 total max	Residuals and trace elements; Al balance

The chemistry of A3004 is tuned to provide additional room-temperature strength relative to 3003 primarily through the Mn content and a controlled copper addition. Manganese acts as a substitutional alloying element that increases work-hardening rate and stabilizes the grain structure during thermomechanical processing. Copper further increases strength and can modestly reduce corrosion resistance; hence its content is limited to maintain good atmospheric performance.

Trace elements and low impurity limits are important to avoid embrittlement, maintain formability, and secure consistent sheet behavior across production batches. Aluminum is the balance element and dominates physical properties such as density and thermal conductivity.

Mechanical Properties

A3004 demonstrates classical strain-hardening tensile behavior: the annealed O temper shows low yield and high elongation, while H-tempers present increased yield and tensile strengths with reduced ductility. Yield behavior in H-tempers is relatively linear with degree of cold work; incremental strain hardening is effective for tailoring mechanical performance to part requirements. Hardness rises predictably with temper and can be used as a production control metric for in-line checks.

Fatigue performance is typical for Al-Mn alloys: endurance limits are lower than steels but adequate for many cyclic-loading applications when stress concentrations are controlled. Fatigue life is sensitive to surface finish, residual stresses from forming, and localized heat-affected zones from welding. Thickness has a direct effect on both strength and ductility observed in tensile tests; thin gages may show higher apparent formability while thicker sections can retain more energy-absorbing capacity.

Springback and anisotropy are practical considerations for stamping and bending; directional properties stemming from rolling must be accounted for in die design. Lightweight structural applications exploit the alloy's favorable strength-to-weight ratio, but design margins should consider reduced notched fatigue and lower fracture toughness than higher-strength heat-treatable aluminum grades.

Property	O/Annealed	Key Temper (e.g., H14/H18)	Notes
Tensile Strength	~120–160 MPa	~200–260 MPa	H-tempers significantly raise UTS by cold work
Yield Strength	~35–70 MPa	~140–190 MPa	Yield scales with temper; measured 0.2% offset
Elongation	~30–40%	~3–15%	Large ductility drop in full-hard conditions
Hardness (HV)	~25–40	~45–85	Hardness increases with strain hardening and correlates to strength

Physical Properties

Property	Value	Notes
Density	2.70–2.74 g/cm³	Typical aluminum alloy density; slight variation due to alloying
Melting Range	~605–660 °C	Solidus–liquidus range influenced by minor alloy additions
Thermal Conductivity	~120–160 W/m·K	Lower than pure Al but still good for heat transfer applications
Electrical Conductivity	~30–38 % IACS	Reduced from pure Al due to alloying; acceptable for conductive components
Specific Heat	~900 J/kg·K	Typical of aluminum alloys at room temperature
Thermal Expansion	~23–24 µm/m·K (20–100 °C)	Comparable to other wrought aluminum alloys

A3004 retains favorable thermal transport characteristics compared with many structural metals, making it useful for heat exchange and thermal management applications. The alloy's electrical conductivity is reduced by manganese and copper additions, so it is not the first choice where maximum conductivity is required, but it is acceptable for conductive structural parts or current-carrying sheet in low-demand contexts.

Thermal expansion and low density support dimensional stability and lightweight design across a moderate temperature range, but engineers must account for expansion and reduced mechanical properties at elevated temperatures when designing assemblies.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.2–6.0 mm	Strength increases with H-tempers	O, H14, H24	Most common form for cladding, fins, and panels
Plate	6–25 mm	Limited availability; thicker sections are harder to cold work	O, H18	Used for structural parts where thickness is essential
Extrusion	Sections up to 200 mm	Strength influenced by extrusion and subsequent cold work	H14, H24	Less common than sheet; custom shapes for brackets and profiles
Tube	0.5–6 mm wall	Performance similar to sheet; drawing processes used	O, H14	Used in HVAC, heat exchanger cores, and small-diameter tubing
Bar/Rod	Ø3–50 mm	Typically supplied in H-tempers; machining stock	H14, H18	Employed for machined components and fasteners where alloy is permitted

Sheet and coil are the dominant commercial product forms for A3004, reflecting its primary use in stamping, drawing, and rolling processes. Extrusions and bars exist but are less prevalent; these forms may require specialized ingot composition control and are used where section geometry drives design.

Processing differences—rolling, annealing cycles, cold work—produce property gradients through thickness and across coil width, which must be accounted for in forming dies and welding design. Suppliers can provide tailored tempering sequences to balance formability and final strength according to production needs.

Equivalent Grades

Standard	Grade	Region	Notes
AA	A3004	USA	Common American Aluminum Association designation
EN AW	3004	Europe	AlMn1Cu type composition in EN standards
JIS	A3004	Japan	Often referenced in Japanese industry for sheet and coil
GB/T	3A05 / 3004 equivalent	China	Local designations may vary; check exact composition

Cross-reference designations vary by standardizing body; the numerical family (3004/3xxx) is consistent, but upper and lower limits for minor elements can differ by specification and producer. When substituting between standards, engineers must check exact chemical and mechanical property limits, especially for copper and manganese minima/maxima which affect strength and corrosion behavior. Surface treatments, coating processes, and temper definitions may also have differing nomenclature and requirement clauses across regions.

Corrosion Resistance

A3004 exhibits good general atmospheric corrosion resistance due to the formation of a stable aluminum oxide film on the surface. In marine or chloride-rich environments the alloy is susceptible to localized pitting; careful selection of coatings, sealants and design to avoid crevices is recommended. The modest copper content slightly reduces corrosion resistance relative to pure Al or 3003 but often yields acceptable lifetime when appropriate surface protection is used.

Stress corrosion cracking is not a major concern for the A3004 composition under normal service temperatures; 3xxx Al-Mn alloys are not highly susceptible to SCC compared with high-strength aluminum alloys. Galvanic interactions with more noble metals (e.g., stainless steel, copper) can accelerate corrosion of A3004 if direct electrical contact and an electrolyte are present; isolation and correct fastener selection mitigate this risk. Compared with 5xxx (Al-Mg) and 6xxx (Al-Mg-Si) families, A3004 trades some resistance to marine pitting for better cold-work performance and lower cost.

Fabrication Properties

Weldability

A3004 is readily weldable by common fusion methods such as TIG and MIG, exhibiting low hot-cracking tendency compared with higher-strength aluminum alloys. Typical filler wires include Al-Si (e.g., 4043) or aluminum alloys compatible with the 3xxx series; selection depends on joint service requirements and desired post-weld corrosion resistance. Welded joints will show localized HAZ softening if they were previously strain hardened, so post-weld mechanical properties should be verified for critical components. Preheating is usually not required for thin sections, but heat management and restraint design control distortion.

Machinability

Machinability of A3004 is moderate; it machines better than pure aluminum but not as well as some Cu- or Pb-bearing alloys designed for easy cutting. Carbide tooling and moderate feed rates produce consistent chip control and surface finish, while high-speed tools can be used if coolant and chip evacuation are managed. Burr formation is manageable, and typical feed/speed windows are similar to other 3xxx series alloys for turning and milling. Threading and tapping require attention to workhardening tendencies in H-tempers.

Formability

A3004 offers excellent formability in the O temper and very good formability in light-to-moderate H-tempers, making it suitable for deep drawing, bending, and roll forming. Minimum bend radii depend on temper and thickness; annealed sheet can achieve tight radii while full-hard tempers require larger radii to avoid cracking. Incremental forming with intermediate anneals or stretch-forming techniques can produce complex geometries without sacrificing final strength. Springback behavior must be accounted for, especially in H-tempers where yield strength is elevated.

Heat Treatment Behavior

A3004 is a non-heat-treatable alloy; it does not respond to solution treatment and artificial aging in the way 6xxx or 7xxx alloys do. Strength increases are achieved exclusively by work hardening (plastic deformation) and by microstructural control during thermomechanical processing. Full annealing (O) is performed to restore ductility, reduce residual stresses, and enable subsequent forming operations.

Annealing cycles are typically performed at temperatures that allow recrystallization without excessive grain growth; manufacturers specify the exact soak and ramp times to guarantee consistent properties. Stabilization or partial reversion heat treatments (e.g., tempering after cold work to set a H24-like condition) are used to control residual stresses and springback in formed components. There is no practical solution-aging regime to achieve precipitation hardening for A3004.

High-Temperature Performance

A3004 experiences progressive strength loss with increasing temperature; above roughly 150–200 °C significant reductions in yield and tensile strength occur, limiting long-term structural use at elevated temperatures. Oxidation is limited by the formation of an adherent Al2O3 scale, which provides some high-temperature protection but does not prevent strength degradation. For short-term exposures to moderately elevated temperatures, the alloy retains useful ductility but designers should perform application-specific testing for creep and relaxation.

Weld heat-affected zones may exhibit altered strength and ductility after exposure to high temperatures, and prolonged thermal cycling can accelerate softening in cold-worked sections. For applications requiring sustained strength above ~150 °C, engineers typically specify heat-resistant alloys or specialist aluminum series with better high-temperature retention.

Applications

Industry	Example Component	Why A3004 Is Used
Automotive	Body panels, trim	Good formability for stamping, improved strength over 3003
HVAC / Heat transfer	Fins, condenser coils	Thermal conductivity and formability for thin fins/coils
Architecture	Cladding, soffits	Surface finish, paintability, and corrosion resistance
Consumer goods	Cookware, appliances	Balance of formability, strength and surface quality
Electronics	Chassis panels, enclosures	Lightweight, thermally conductive structural panels

A3004 is favored where manufacturability and economics meet functional performance: it can be formed into complex shapes, retains adequate strength after forming, and accepts surface treatments and joining methods with predictable behavior. The alloy’s combination of properties supports high-volume production parts that require a balance of ductility and elevated strength without resorting to heat treatment steps.

Selection Insights

For an engineer deciding whether to specify A3004, focus on the balance between formability, moderate strength, and cost. Choose A3004 over commercially pure aluminum (1100) when higher yield and tensile strength are needed while still retaining good forming and weldability characteristics. It gives up some electrical conductivity and maximum ductility compared with 1100, but offers meaningful strength advantages for stamped or drawn parts.

Compared with other work-hardened alloys like 3003 and 5052, A3004 sits between them: it is stronger than 3003 due to copper and manganese additions and often comparable in corrosion resistance to 3003, while 5052 provides superior corrosion resistance in marine environments and higher strength in many tempers. Select 5052 when chloride resistance is paramount, but pick A3004 when forming operations and cost sensitivity dominate the decision.

When compared with heat-treatable alloys such as 6061 or 6063, A3004 is chosen where the complexity and processing cost of solution/aging are not justified. Use A3004 for highly formable sheet applications with moderate final strength needs; reserve 6061/6063 for applications requiring higher peak strength or structural performance at elevated temperatures.

Closing Summary

A3004 remains a practical and widely used 3xxx series aluminum alloy that fills the niche between highly ductile commercial-purity material and more complex heat-treatable alloys. Its controlled chemistry and reliable strain-hardening response make it an economical choice for formed, painted, and welded parts in architecture, HVAC, automotive and consumer goods. Designers select A3004 when the optimal combination of formability, mid-range strength, and cost-effectiveness is required for production-scale manufacturing.