Aluminum 1050: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

Alloy 1050 belongs to the 1xxx series of wrought aluminum alloys and is classified as a commercially pure aluminum with a minimum aluminum content of approximately 99.5%. The alloying content is intentionally minimal so that electrical and thermal conductivity, together with excellent corrosion resistance and formability, remain the dominant material attributes. Strength in 1050 is achieved primarily through work hardening (strain hardening) rather than precipitation or solution heat treatment, so it is considered a non-heat-treatable alloy. Typical traits include low-to-moderate tensile strength, very good ductility in the annealed condition, excellent corrosion resistance in many atmospheres, and outstanding electrical and thermal conductivity, making it a preferred choice for applications where forming, conductivity, and corrosion resistance are key.

Industries that frequently specify 1050 include electrical (bus bars, conductors), HVAC and heat-exchange equipment (fins, radiators), chemical processing (corrosion-resistant components), decorative trim and signage, and some lightweight structural uses where high formability is required. Designers select 1050 when maximum ductility and conductivity are required, or when cost and ease of fabrication outweigh the need for high mechanical strength. The alloy is chosen over stronger multi-alloy systems when severe forming or deep drawing is required, or when galvanic compatibility and high electrical conductivity are essential.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High (≈35–45%)	Excellent	Excellent	Fully annealed condition with maximum ductility.
H14	Medium	Moderate (≈20–30%)	Good	Excellent	Strain-hardened to a quarter-hard condition; commonly used for moderate strength increase.
H16	Medium-High	Lower (≈15–25%)	Fair	Excellent	Strain-hardened to a half-hard condition; balances strength and formability.
H18	High (for 1xxx)	Low (≈8–15%)	Limited	Excellent	Strain-hardened to full-hard; used where strength and springback control are needed.
T5 / T6 / T651	N/A	N/A	N/A	N/A	Not applicable; 1050 is non-heat-treatable and does not respond to precipitation aging.

Temper has a direct and predictable effect on 1050 performance: cold work (H-temper) raises yield and tensile strengths while progressively reducing ductility and formability. The annealed O condition delivers the best formability and highest elongation for deep drawing and complex stamping, while H-tempers are selected when dimensional stability, springback characteristics, or higher operational strength are required.

Chemical Composition

Element	% Range	Notes
Si	0.25 max	Impurity; controlled to limit casting embrittlement and maintain conductivity.
Fe	0.40 max	Principal impurity; increases strength slightly but can reduce ductility and conductivity.
Mn	0.05 max	Low; not used for strengthening in this alloy family.
Mg	0.03 max	Negligible; limits susceptibility to certain corrosion phenomena.
Cu	0.05 max	Minimal; small amounts increase strength but can reduce corrosion resistance.
Zn	0.05 max	Trace; kept low to preserve conductivity and corrosion resistance.
Cr	0.05 max	Minor; can control grain structure at trace levels.
Ti	0.03 max	Often used as grain refiner in processing but present only in trace amounts.
Others (each)	0.05 max	Other impurities individually limited to preserve purity.
Al	Balance (min ~99.5%)	Principal component; high-purity aluminum governs the alloy characteristics.

The near-purity of 1050 means that aluminum matrix properties dominate performance. Trace impurities (Fe, Si, Cu) influence mechanical strength and conductivity: higher iron and silicon slightly increase strength but can reduce electrical performance and formability. Maintaining tight controls on minor element levels preserves the alloy’s hallmark attributes: high conductivity, good corrosion resistance, and excellent ductility.

Mechanical Properties

In the annealed O condition, 1050 exhibits low yield strength and tensile strength but very high elongation, which translates to excellent forming behavior during deep drawing and rolling operations. Yield strength in O condition is low and can vary with thickness and processing history, typically giving designers a large safety margin for forming but requiring consideration for buckling and stiffness-limited designs. Cold working by rolling, drawing, or bending raises both yield and tensile strength via strain hardening; H-tempers trade ductility for higher strength and springback control.

Hardness values for 1050 are low in the annealed state, reflecting the soft, ductile microstructure, and increase predictably with cold work. Fatigue performance is typical of commercially pure aluminum: fatigue strength is modest and strongly influenced by surface condition, residual stresses from forming, and environmental factors such as corrosion. Thickness affects mechanical values: thinner gauges often show higher apparent strength due to work-hardening in processing, while thicker sections may be relatively softer and less responsive to cold working.

Property	O/Annealed	Key Temper (e.g., H14)	Notes
Tensile Strength (MPa)	55–75	95–130	Values depend on gauge, processing, and exact temper; H14 roughly doubles strength vs O.
Yield Strength (0.2% proof, MPa)	20–40	60–100	Yield increases with degree of work hardening; use test coupons for design-critical parts.
Elongation (%)	35–45	15–30	Ductility declines with hardening; O condition required for deep drawing.
Hardness (HB)	15–25	30–45	Brinell values for cold-worked tempers increase as expected for aluminum alloys.

Physical Properties

Property	Value	Notes
Density	2.71 g/cm³	Typical of aluminum alloys; useful for mass and stiffness calculations.
Melting Range	~660 °C	Solidus and liquidus are close since alloy is near-pure aluminum.
Thermal Conductivity	~220–235 W/m·K	High thermal conductivity; excellent for heat sink and heat-exchange applications.
Electrical Conductivity	~58–62 % IACS	Among the higher conductivities for wrought alloys, favoring electrical and busbar use.
Specific Heat	~0.90 J/g·K (900 J/kg·K)	Standard value for heat capacity calculations.
Thermal Expansion	~23.6 ×10^-6 /K (20–100 °C)	Moderate coefficient; must be accounted for in thermal cycling designs.

The high thermal and electrical conductivities stem from the alloy’s low solute content and are among the principal reasons 1050 is selected for electrical and heat-transfer components. Density is sufficiently low to provide favorable specific strength for non-structural components, and the melting behavior requires standard aluminum melting practices for casting or brazing processes. Thermal expansion is typical for aluminum and can be large relative to steels, so differential expansion should be accounted for in multi-material assemblies.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.2 mm – 6 mm	Cold working during rolling can produce H-tempers	O, H14, H16, H18	Widely used for deep drawing, cladding, and decorative finishes.
Plate	>6 mm up to 25 mm	Thicker sections are softer and less responsive to cold work	O, H14	Less common in very thick plates; used where corrosion resistance outweighs stiffness.
Extrusion	Profiles up to large cross-sections	Extruded profiles typically start O and may be cold-worked	O, H14	Good surface quality and dimensional stability; useful for lightweight frames and conductive rails.
Tube	Various diameters/wall thicknesses	Mechanical properties influenced by cold drawing	O, H16	Used for fluid handling, structural tubing where corrosion and formability matter.
Bar/Rod	Round/hex up to large diameters	Cold working increases strength for springs and fasteners	O, H18	Common for rivets, pins, and lightweight fasteners where high ductility or moderate strength is needed.

Different product forms are produced by distinct processing routes that influence final properties. Sheet and foil production involves rolling and annealing cycles that set temper and grain size; extrusions and tubes are shaped by hot extrusion and often finish-cold-drawn to achieve dimensional precision. Designers should specify temper and post-processing (e.g., anneal after heavy forming) to obtain predictable mechanical performance and dimensional control.

Equivalent Grades

Standard	Grade	Region	Notes
AA	1050	USA	ASTM/AA designation for commercially pure Al with ~99.5% Al.
EN AW	1050A	Europe	EN standard variant often labeled EN AW-1050A with similar chemical limits.
JIS	A1050	Japan	Japanese Industrial Standard equivalent, commonly used in electrical and general applications.
GB/T	Al99.5 / 1050	China	Chinese standard designations refer to high-purity Al grades comparable to AA1050.

Equivalency across standards is close, but small differences in impurity limits and processing designations (e.g., 1050 vs 1050A) can influence final properties, particularly conductivity and surface finish. When substituting cross-region, verify the exact chemical limits and temper naming conventions, and confirm mechanical test data and surface condition for critical electrical or drawn applications.

Corrosion Resistance

1050 exhibits very good general corrosion resistance in atmospheric and mildly aggressive environments due to formation of a stable, adherent Al2O3 passive film. In neutral and alkaline aqueous environments the alloy performs well, and it resists many organic chemicals and oxidizing salts; however, in chloride-rich marine environments localized pitting can occur if crevices or deposits concentrate chlorides on the surface. Surface finish and presence of cold work influence susceptibility to localized corrosion, with polished or anodized surfaces providing enhanced protection.

Stress corrosion cracking is not a common failure mode for commercially pure aluminum like 1050 in typical service conditions; however, sustained tensile stresses combined with corrosive species can still precipitate environmental failures in severe cases. Galvanic interactions are important: 1050 is anodic relative to copper and stainless steel and will corrode preferentially when electrically connected in moist environments. Designers should manage dissimilar metal contact with isolation materials or protective coatings to avoid accelerated galvanic attack.

Compared with other alloy families, 1050 often outperforms many heat-treatable alloys in general corrosion resistance because of its higher purity and fewer galvanic micro-constituents. Compared to 5xxx (Mg-bearing) alloys, 1050 has lower intrinsic strength but similar or slightly different marine pitting behavior; 5xxx alloys often provide superior strength and overall marine corrosion resistance where strength is critical.

Fabrication Properties

Weldability

1050 is highly weldable by common fusion and resistance processes such as TIG (GTAW), MIG (GMAW), and spot welding, with low susceptibility to hot cracking because of its low alloy content. Typical filler rods include commercially pure aluminum filler (AA1100) or Al-Si based fillers (e.g., 4043) when improved flow or reduced cracking sensitivity is desired. Heat-affected-zone softening is not a concern in the same way as for heat-treatable alloys, but distortion and residual stress from welding should be controlled for thin sections.

Machinability

Machinability is modest for 1050 and is generally lower than typical free-machining aluminum alloys and significantly lower than some leaded or silicon-containing alloys. Recommended tooling is sharp carbide with moderate positive geometry to avoid built-up edge; speeds and feeds should be conservative to prevent work hardening at the cut surface. Chip formation is typically continuous and ductile; effective chip evacuation and lubricant/coolant control are essential for finishing surfaces and maintaining dimensional precision.

Formability

Formability of 1050 is excellent in the annealed O condition with very low forming forces and the ability to achieve tight bend radii and deep-drawn shapes. Bend radii can be taken down to a few times material thickness in O temper for many operations, but springback increases after work hardening so tool design must account for H-tempers. Cold forming is the primary hardening route and can be used strategically to produce H-tempers from O material once the required geometry is established.

Heat Treatment Behavior

Because 1050 is a non-heat-treatable alloy, it does not respond to solution treatment and precipitation aging in the manner of 6xxx or 7xxx series alloys. Property modification is achieved almost exclusively through mechanical means: cold working (rolling, drawing, bending) increases strength via dislocation density increase and grain distortion. Full annealing to restore ductility can be achieved by heating to appropriate temperatures (commonly in the range of 300–415 °C depending on section size and desired recrystallization) followed by controlled furnace cooling; this reduces residual stresses and returns the material to an O-like condition.

When annealing, care should be taken to avoid overheating which can cause grain growth and degrade surface and mechanical properties. Normalization between forming passes and stress-relief operations can be performed to stabilize dimensions and mechanical response, but there is no classical T-temper aging sequence applicable for strengthening as with heat-treatable alloys.

High-Temperature Performance

Mechanical strength of 1050 degrades rapidly with temperature, and designers should generally limit continuous service temperatures to well below 150 °C for load-bearing applications to avoid significant loss of yield and tensile strength. Oxidation resistance at elevated temperatures is provided by an aluminum oxide layer, which remains protective in many environments, but elevated temperatures combined with corrosive atmospheres accelerate mass loss and creep-like deformation in thin sections. Welded joints and heat-affected zones can experience local changes in mechanical behavior when exposed to elevated temperatures, though the absence of precipitation-hardening constituents limits complex temper transitions.

For short-term exposures or heat treatments, 1050 can tolerate elevated temperatures, but long-term mechanical property retention is poor compared with heat-resistant alloys; designers should select higher-temperature aluminum or other alloy systems when sustained elevated-temperature strength is required.

Applications

Industry	Example Component	Why 1050 Is Used
Electrical	Bus bars, conductors, grounding strips	High electrical conductivity and good formability.
HVAC / Heat Exchange	Fins, radiators, condenser components	Excellent thermal conductivity and ease of forming into thin, high-surface-area shapes.
Chemical Processing	Tanks, cladding, fittings	Good general corrosion resistance and purity for chemical compatibility.
Consumer / Decorative	Trim, signage, reflectors	Bright finishability, corrosion resistance, and ease of stamping.
Packaging	Foils, containers	Ductility and malleability for forming thin sections with consistent sealing behavior.

1050 is selected in applications where electrical or thermal conductivity, corrosion resistance, and deep drawability are prioritized over high structural strength. Its ubiquity in electrical, HVAC, and decorative markets stems from the combination of high purity, predictable forming behavior, and cost-effective supply.

Selection Insights

Choose 1050 when maximum formability, high electrical or thermal conductivity, and excellent corrosion resistance are primary requirements and when only modest mechanical strength is acceptable. It is particularly economical for parts that require extensive cold forming or where high surface quality and conductivity are required.

Compared with 1100, 1050 typically offers slightly higher purity and marginally improved conductivity at similar ductility, making 1050 preferable when conductivity is prioritized. Compared with work-hardened alloys such as 3003 or 5052, 1050 trades lower strength for higher conductivity and generally equivalent or slightly different corrosion performance; select 3003/5052 when increased strength or specific marine resistance is required. Compared with heat-treatable alloys such as 6061 or 6063, 1050 is chosen for forming ease, lower cost, and superior conductivity even though those heat-treatable alloys deliver much higher peak strengths and stiffness.

Closing Summary

Aluminum 1050 remains a mainstay material where its combination of very high purity, exceptional formability, and strong electrical and thermal conductivity are needed; its predictable work-hardening behavior and excellent corrosion resistance make it a practical, economical choice for numerous industrial and consumer applications.