Aluminum 3103: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

Alloy 3103 is a member of the 3xxx series aluminum-manganese family, positioned as a commercially alloyed, non-heat-treatable wrought alloy. Its primary microalloying element is manganese, with small additions and controlled impurities of silicon, iron, copper, and magnesium to tune strength and formability.

Strength in 3103 is generated predominantly by solid-solution effects and strain hardening during cold working rather than by precipitation heat treatment. The alloy balances moderate strength with very good ductility, excellent corrosion resistance in many atmospheric environments, and facile weldability and formability for sheet and extrusion products.

Industries that typically specify 3103 include architectural cladding, general fabrication, HVAC components, and consumer goods where deep drawing or significant forming is required. Engineers select 3103 over purer alloys when a modest increase in mechanical performance is needed without sacrificing formability or significantly increasing cost relative to common 1xxx and 3xxx alloys.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Annealed condition; maximum ductility for forming
H14	Moderate	Moderate	Very Good	Excellent	Lightly strain-hardened; common for drawn parts
H18	High	Lower	Good	Excellent	Heavier work-hardening for added stiffness
H24	Moderate	Moderate	Very Good	Excellent	Strain-hardened and partially annealed for balance
H22 / H26	Moderate–High	Moderate–Low	Good	Excellent	Intermediate hardening levels commonly supplied

Tempering 3103 changes properties almost exclusively via cold work; O (annealed) provides the best ductility and formability, while H-temper variants incrementally increase yield and tensile strengths. Heat-treatable T-tempers are not applicable to 3xxx manganese alloys in the same way as Al-Mg-Si or Al-Cu systems, so temper choices are focused on combinations of cold work and recovery anneals.

Chemical Composition

Element	% Range	Notes
Si	0.20–0.60	Impurity level; higher Si increases strength slightly but reduces ductility
Fe	0.40–1.20	Common impurity that forms intermetallics and can reduce elongation
Mn	0.80–1.50	Primary alloying element; provides solid-solution strengthening and grain structure control
Mg	0.05–0.50	Small amounts can aid strength; not a primary hardening mechanism
Cu	0.05–0.20	Controlled low Cu to limit susceptibility to localized corrosion
Zn	0.05–0.30	Minor; kept low to avoid unintended precipitation hardening
Cr	0.05 max	Trace levels to control recrystallization in some products
Ti	0.05 max	Grain refiner in cast or certain wrought processing routes
Others	Balance Al, residuals	Including trace elements such as Pb, Sn controlled per spec

The manganese level is the defining compositional control for 3103 and is responsible for most of the alloy’s mechanical differentiation from purer grades. Silicon and iron are typical residuals from raw materials and manufacturing; their morphology and size of intermetallics influence ductility and formability in drawn or deep-drawn components.

Mechanical Properties

Under annealed conditions 3103 exhibits modest tensile and yield strengths with relatively high elongation, which makes it suitable for forming and drawing operations. Cold-working to H-temper levels increases yield and tensile strengths at the expense of ductility, allowing designers to select a compromise between stiffness and formability. Hardness correlates with temper and is typically in the low Brinell range for O temper, rising with higher H tempers; fatigue strength is moderate and dependent on surface finish and cold working.

Thickness affects mechanical response: thinner gauge sheet can be drawn more readily and work-hardens more uniformly, while thicker plate or extrusions retain larger grain sizes and may show higher residual stresses after forming. The heat-affected zone from welding is generally not prone to embrittlement since the alloy does not rely on precipitate hardening, but localized softening from annealing of cold-worked regions can occur near welds.

Property	O/Annealed	Key Temper (e.g., H14/H18)	Notes
Tensile Strength	100–145 MPa	140–190 MPa	Range depends on gauge and exact temper; H18 near upper range
Yield Strength	40–80 MPa	90–140 MPa	Yield increases significantly with strain-hardening
Elongation	20–38%	6–18%	Annealed very ductile; H-tempers reduce ductility
Hardness	25–50 HB	50–85 HB	Brinell approximate; increases with work hardening

Physical Properties

Property	Value	Notes
Density	2.70 g/cm³	Typical for wrought Al-Mn alloys; useful for weight-sensitive design
Melting Range	645–660 °C	Solidus–liquidus interval typical of wrought aluminum alloys
Thermal Conductivity	120–150 W/(m·K)	Lower than pure Al but still high for thermal management
Electrical Conductivity	30–40 % IACS	Reduced from pure Al due to alloying; adequate for some bus and conductor uses
Specific Heat	0.90 kJ/(kg·K)	Typical room-temperature value for design heat capacity
Thermal Expansion	23.5 ×10⁻⁶ /K	Coefficient of linear expansion near that of most aluminium alloys

3103 retains much of aluminum’s favorable thermal conductivity and specific heat, making it suitable for moderate thermal-management roles where excellent formability is also required. Its electrical conductivity is lower than CP-Al but remains adequate for applications where mechanical properties and forming are prioritized over maximum conductivity.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.2–6.0 mm	Uniform thin-gauge work-hardening	O, H14, H18	Widely used for drawing, stamping, facades
Plate	6–25 mm	Lower formability; larger grain	O, H22	Used for structural panels and fabrication
Extrusion	Wall thickness 1–10 mm	Directional strength; anisotropy possible	O, H14	Profiles for architectural trims and channels
Tube	OD 6–168 mm	Good drawability for seamless/p welded tubes	O, H14	HVAC ducting and ornamental tubing
Bar/Rod	Dia 3–50 mm	Less common; moderate machinability	O, H14	Fasteners, turned components where formability less important

Sheet and coil are the most prevalent product forms for 3103 because the alloy’s principal advantages are formability and ease of surface finishing. Extrusions and tubes take advantage of the alloy’s flow characteristics during hot and cold deformation, whereas plate and bar are used where forming demands are lower and dimensional stability or stiffness becomes more important.

Equivalent Grades

Standard	Grade	Region	Notes
AA	3103	USA	American Aluminum Association designation
EN AW	3103	Europe	European wrought designation, similar chemistry and properties
JIS	A3103	Japan	JIS designation aligning with Al-Mn alloy family
GB/T	3103	China	Chinese standard for wrought Al-Mn alloys

Regional standards for 3103 are broadly harmonized in composition and permitted impurities but can differ in allowable ranges for elements like Fe and Si, as well as in temper definitions. These subtle differences affect final microstructure, especially intermetallic morphology, which in turn can influence deep-drawing performance and surface aesthetics in architectural applications.

Corrosion Resistance

3103 offers very good atmospheric corrosion resistance comparable to other Al-Mn alloys because manganese does not significantly increase galvanic susceptibility. In rural and urban exposures the alloy forms a stable oxide film that protects the substrate; performance in industrial atmospheres is acceptable though sulfurous and acidic pollutants accelerate localized attack compared with benign environments.

In marine or highly chloride-rich environments 3103 performs moderately well, but it is less durable than 5xxx series Al-Mg alloys specifically designed for marine service. Stress corrosion cracking is uncommon in 3103 because it is not precipitation-hardenable; however, galvanic interactions with more noble materials like stainless steel and copper can accelerate localized corrosion if design details permit electrolyte entrapment. Compared with 1xxx family (CP-Al) the 3103 alloy often shows improved mechanical performance with similar or slightly reduced corrosion resistance, while compared to 5xxx alloys it trades some corrosion robustness for better formability.

Fabrication Properties

Weldability

3103 welds readily with conventional fusion processes (TIG/MIG) and shows low susceptibility to hot cracking due to its non-heat-treatable nature. Recommended filler wires are often 3xxx-series compositions or general-purpose Al-Mg fillers when increased ductility is desired; filler selection should consider post-weld forming requirements. Heat input control is important to avoid excessive softening of adjacent cold-worked regions, though overall HAZ softening is less problematic than in age-hardenable alloys.

Machinability

Machinability of 3103 is moderate and slightly lower than free-machining Al alloys with lead or bismuth. Use of sharp carbide tooling, moderate cutting speeds, and good chip evacuation yields consistent surface finishes; feed rates influence burr formation in thin sections. Cutting tool geometry that promotes continuous chip formation and minimizes built-up edge will improve productivity, particularly in turning and drilling operations.

Formability

Formability is one of 3103’s prime advantages, with low to moderate yield strength in O temper enabling deep drawing, roll forming, and complex bending. Minimum bend radii depend on temper and thickness; in O temper a rule-of-thumb internal bend radius of 0.5–1.0× thickness is commonly achievable without cracking. For severe forming operations H14 or intermediate H tempers can be selected for springback control, while intermediate anneals restore ductility when multiple forming steps are needed.

Heat Treatment Behavior

3103 is a non-heat-treatable alloy; strength modulation is achieved by cold work and controlled annealing rather than solution treatment and aging cycles. Typical annealing (O) is performed at temperatures sufficient to recrystallize and relieve work hardening, restoring ductility for subsequent forming operations. Artificial aging cycles intended to precipitate strengthening phases are not effective for this alloy family, so thermal processing focuses on recovery and grain growth control.

For production workflows, manufacturers toggle between anneal and cold-working sequences to reach desired H-tempers; partial anneals (H24 style) provide a balance between retained formability and increased yield by allowing limited recrystallization. Careful control of thermal exposure during fabrication and welding is necessary to avoid unintentional softening or grain coarsening that can degrade mechanical performance and surface finish.

High-Temperature Performance

Strength retention of 3103 degrades progressively with temperature; significant softening begins above approximately 150–200 °C and performance is generally considered unsuitable for structural loads at elevated temperatures. Oxidation is limited at these temperatures due to the protective alumina scale, but prolonged exposure accelerates grain growth and coarsening of intermetallics, which lowers ductility and fatigue resistance. The alloy is well-suited for short-term thermal excursions and moderate service temperatures but not for continuous high-temperature structural applications.

Weld heat-affected zones can experience localized tempering effects; because the alloy is not precipitation-hardened these changes manifest predominantly as reduced cold-work strengthening and localized changes in grain structure rather than classic overaging. Designers should derate allowable stresses for components exposed to sustained elevated temperatures and consider alternative alloys for continuous service above 200 °C.

Applications

Industry	Example Component	Why 3103 Is Used
Architectural	Cladding & soffit panels	Excellent formability and surface finish for complex shapes
HVAC / Ducting	Air ducts and plenums	Easy fabrication, corrosion resistance, and low weight
Consumer Goods	Kitchen appliances, cookware exteriors	Drawability and surface treatment compatibility
Automotive	Interior trim, non-structural body panels	Balance of formability and increased strength vs CP-Al
Electronics	Heat spreader housings	Good thermal conductivity with easy stamping

3103’s combination of formability, modest strength, and corrosion resistance makes it a practical choice for many non-structural components that require extensive forming and attractive surface finishes. The alloy’s ease of fabrication reduces manufacturing complexity and cost for high-volume stamped or drawn parts.

Selection Insights

For an engineer choosing between 3103 and commercially pure aluminum (e.g., 1100), 3103 offers higher tensile and yield strength at the cost of slightly reduced electrical and thermal conductivity. Choose 3103 when forming complexity and a modest strength increase matter more than achieving maximum conductivity.

Compared with other work-hardened alloys like 3003 and 5052, 3103 generally sits between 3003 and 5052 in terms of strength and corrosion resistance: it provides improved strength over 1100/3003 while maintaining better formability than Mg-rich 5xxx alloys. Use 3103 when you need more strength than 3003 but must preserve deep-drawability and surface finish.

Against heat-treatable alloys such as 6061 or 6063, 3103 will not reach their peak strengths, but it is often preferred when complex forming, lower cost, or improved corrosion/formability balance is required. Select 3103 for stamped or drawn geometries where post-forming heat treatment is impractical.

Closing Summary

Alloy 3103 remains a practical engineering aluminum for parts that prioritize formability, corrosion resistance, and cost-effective fabrication while requiring modest strength improvements over commercially pure grades. Its non-heat-treatable nature simplifies manufacturing workflows and makes it a staple for stamped, drawn, and extruded components across architecture, HVAC, and consumer product sectors.