Aluminum A1070: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

A1070 is a commercially pure aluminum in the 1xxx series, characterized by an aluminum content typically of 99.7% minimum and classified among the highest-purity industrial Al alloys. The 1xxx series designation indicates minimal intentional alloying; typical residual elements include small amounts of Si, Fe, Cu, Mn, Mg, Zn and Ti present as controlled impurities rather than strengthening additions.

Strengthening in A1070 is achieved almost exclusively by work hardening (strain hardening) and grain structure control rather than by precipitation heat treatment. Key traits include excellent electrical and thermal conductivity, superior corrosion resistance in many environments, excellent formability in the annealed condition, and good weldability; tensile strength is low compared with alloyed series but ductility and conductivity are among the highest for structural Al products.

Typical industries for A1070 include electrical conductors, chemical process equipment linings, architectural components, and forming-intensive components for consumer and industrial goods. Engineers choose A1070 when high conductivity, excellent surface quality, and maximum formability with good corrosion resistance take precedence over peak mechanical strength.

A1070 is selected over other alloys when purity-driven properties are required, such as in electrical or chemical-contact applications, or where complex cold forming is needed without the risk of embrittlement from alloying additions. It is also preferred in applications that exploit its compatibility with coatings, anodizing and joining processes where consistent, predictable behavior is essential.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High (30–45%)	Excellent	Excellent	Fully annealed, maximum ductility and conductivity
H12	Low–Moderate	Moderate (20–30%)	Very Good	Excellent	Quarter-hard by limited strain hardening
H14	Moderate	Moderate (15–25%)	Good	Excellent	Typical half-hard temper for sheet forming
H16	Moderate–High	Lower (10–20%)	Fair	Excellent	Three-quarter hard, used where springback is needed
H18	High	Low (5–12%)	Limited	Excellent	Fully hard by extensive cold work, reduced ductility
H111	Low–Moderate	Moderate (20–30%)	Very Good	Excellent	Slightly strain-hardened with natural aging allowed

Temper selection markedly affects the balance between strength and ductility in A1070; annealed O temper offers the best formability and highest electrical/thermal conductivity, while H‑tempers trade ductility for incremental strength via cold work. Work hardening introduces yield and tensile increases but reduces elongation and formability; temper choice should match forming processes and end-use mechanical demands.

Chemical Composition

Element	% Range	Notes
Si	≤ 0.25	Impurity; excess can reduce conductivity and increase casting/rolling inclusions
Fe	≤ 0.40	Common impurity; forms intermetallics that influence strength and surface finish
Mn	≤ 0.03	Minimal; not a deliberate alloying element in 1xxx alloys
Mg	≤ 0.03	Controlled impurity; higher levels would move alloy out of 1xxx series
Cu	≤ 0.05	Minor, reduces corrosion resistance at higher concentrations
Zn	≤ 0.03	Minor, generally not intentional
Cr	≤ 0.03	Trace; can influence grain structure if present in larger amounts
Ti	≤ 0.02	Grain refiner in small quantities when intentionally added
Others (each)	≤ 0.05; total ≤ 0.15	Other residuals include Ni, Pb, Bi; kept low to preserve conductivity and ductility

The near‑pure aluminum composition of A1070 is deliberate: minimal alloy content preserves high electrical and thermal conductivity and yields excellent resistance to general corrosion due to a uniform, adherent oxide film. Trace impurities (Fe, Si) produce discrete intermetallic particles that raise strength slightly but can affect surface finish, formability and conductivity when present in higher amounts.

Mechanical Properties

A1070 exhibits classic soft aluminum tensile behavior: the annealed condition provides low yield and tensile strengths with high elongation, while cold working (H‑tempers) increases yield and tensile strengths at the expense of ductility. Yield behavior is gradual rather than sharply defined in very pure aluminum; engineers should use 0.2% offset yield values for design and account for variability due to gauge and processing history.

Hardness values are low in O temper and increase proportionally with cold work. Fatigue performance is limited by low strength and a high propensity for surface-initiated cracks under reversed loading; however, the alloy’s ductility delays crack initiation when parts are well finished and free of notches. Thickness and surface condition significantly influence mechanical properties, with thinner gauges typically showing higher measured strengths after cold rolling and better material homogeneity.

Property	O/Annealed	Key Temper (e.g., H14)	Notes
Tensile Strength	65–95 MPa typical	95–145 MPa typical	Values depend on thickness and strain hardening level
Yield Strength	30–60 MPa typical	60–120 MPa typical	Use 0.2% offset yield; cold work raises yield more than UTS proportionally
Elongation	30–45% typical	15–25% typical	Elongation drops with increasing temper; gauge influences values
Hardness	15–30 HB	25–45 HB	Hardness tracks temper and cold work; can be measured by Brinell or Vickers

Physical Properties

Property	Value	Notes
Density	2.70 g/cm³	Typical for commercial aluminum, used in mass and strength-to-weight calculations
Melting Range	660–657 °C (solidus ≈ 660 °C)	Narrow melting point typical of high-purity aluminum
Thermal Conductivity	≈ 220–235 W/m·K (room temp)	Among the highest for aluminum alloys; excellent for heat-sinking
Electrical Conductivity	≈ 58–64 % IACS	Very high conductivity, close to pure Al benchmarks
Specific Heat	≈ 900 J/kg·K	Useful for thermal mass calculations in thermal management
Thermal Expansion	≈ 23–24 ×10⁻⁶ /K (20–100 °C)	Relatively high coefficient compared with steels; important for design of assemblies

A1070’s physical profile makes it attractive where heat transfer or electrical conduction are primary design drivers. Engineers must account for aluminum’s relatively high coefficient of thermal expansion when mating A1070 components with dissimilar materials to avoid joint stresses during temperature excursions.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.2–6.0 mm	Strength increases with cold rolling	O, H12, H14, H16	Widely used for deep drawing and rolled products
Plate	6–25 mm	Similar trends; thicker plate may be less cold worked	O, H111	Less common due to alloy’s focus on thin gauge applications
Extrusion	up to large cross-sections	Extruded properties depend on cooling and subsequent work	O, H14	Limited compared with 6xxx alloys but used where purity is needed
Tube	Various diameters/walls	Mechanical properties similar to sheet of comparable work	O, H14, H16	Good for welded and drawn tubes for chemical or architectural use
Bar/Rod	Ø 2–200 mm	Machinability and strength vary with temper	O, H14	Rods used in conductor and fabricated parts manufacturing

Processing route (rolling vs extrusion vs drawing) affects final grain structure and mechanical anisotropy in A1070. Thin gauge sheet benefits most from the alloy’s formability for deep drawing and complex stamping, while extrusions are selected where cross-sectional purity and surface finish are priorities.

Equivalent Grades

Standard	Grade	Region	Notes
AA	A1070	USA	Original Aluminum Association designation for high-purity 1070 alloy
EN AW	AW-1070	Europe	EN designation aligns closely; European standards may set slightly different impurity limits
JIS	A1070	Japan	Japanese standard generally equivalent but with local specification tolerances
GB/T	1070	China	Chinese standard equivalent in classification; check local tables for exact composition limits

Equivalent grade labels across standards are intended to represent the same high‑purity 1xxx family behavior, but sheet mill practices and allowable impurity tolerances can vary by standard. When specifying cross‑standard equivalents, review the actual chemical and mechanical limits in the referenced specification to ensure interchangeability for critical properties like conductivity or surface quality.

Corrosion Resistance

A1070 exhibits excellent general atmospheric corrosion resistance due to a stable and rapidly forming aluminum oxide film that passivates the surface. In rural and industrial atmospheres the alloy performs very well and often outperforms alloyed series where impurities or second-phase particles drive localized corrosion.

In marine environments A1070 has good resistance to uniform corrosion but can be susceptible to pitting and crevice corrosion in concentrated chloride environments if surface deposits and oxygen deprivation occur. Stress corrosion cracking is uncommon in very pure aluminum compared with certain heat-treatable alloys; however, tensile stressed components in corrosive chloride environments should still be designed conservatively and tested.

Galvanic interaction must be considered since A1070 is anodic relative to many common metals (stainless steels, copper, brass); it will preferentially corrode when electrically coupled in an electrolyte unless electrically insulated. Compared with 5xxx (Al-Mg) series, A1070 often offers superior conductivity and comparable general corrosion resistance, while 5xxx alloys can be more resistant to localized corrosion in seawater when properly alloyed.

Fabrication Properties

Weldability

A1070 welds readily by common fusion processes such as TIG and MIG using appropriate shielding and clean surfaces; welding does not introduce significant hardenability issues because the alloy is non-heat-treatable. Recommended filler wires are those that match or slightly alloy the joint (e.g., ER1100 for like-to-like welding) or Al‑Mg fillers for marine joints where enhanced corrosion resistance is desired; selection should consider galvanic compatibility and joint service. Hot‑cracking risk is generally low but depends on joint design, cleanliness and residual impurities; weld HAZ does not exhibit the same softening concerns as precipitation‑hardening alloys since A1070 gains strength only by cold work.

Machinability

Machinability of A1070 is fair but often lower than some wrought alloy grades due to its softness and tendency to form continuous, gummy chips under poor tooling conditions. Carbide tooling with positive rake and good chip breakers, high feed rates and effective lubrication/coolant improve surface finish and tool life. Surface finish and dimensional control are typically good when using proper tooling systems, but allowance for springback and burr formation should be included in process planning.

Formability

Formability in the annealed O temper is excellent: A1070 is favorable for deep drawing, spinning and bending with small bend radii relative to many alloyed grades. Bend radii can be quite small in O temper (sometimes less than 1× thickness for mild deformation) but increase with H‑tempers as strain hardening reduces ductility. For complex forming sequences, start from O temper or apply intermediate anneals to avoid cracking and maintain tight tolerances.

Heat Treatment Behavior

A1070 is not a heat-treatable alloy; it does not respond to solution treatment and artificial aging to produce strengthening precipitates. Attempts to “age” 1xxx alloys do not produce the marked hardness and strength increases seen in 2xxx–7xxx alloys, so thermal processing is primarily used for annealing and stress‑relief.

Work hardening through cold deformation is the primary method for improving strength, and this effect can be reversed or reduced by annealing. Full annealing is typically performed at temperatures in the 350–415 °C range to restore ductility and conductivity, followed by slow cooling to avoid thermal gradients and resultant distortion.

High-Temperature Performance

A1070 loses mechanical strength rapidly as temperature increases above ambient; while it retains some load-carrying capability to several hundred degrees Celsius, practical design limits for structural stiffness and strength are usually set below 100–150 °C for continuous service. Oxidation at elevated temperatures produces a thicker oxide scale that generally remains protective, but scaling and softening may limit suitability in prolonged high-temperature service.

Welded regions and heat-affected zones do not suffer from aging-related softening but will show reduced yield relative to cold-worked parent material if the component relied on strain hardening for strength. For intermittent high-temperature exposure, designers should assess creep and reduction in modulus for long-term performance.

Applications

Industry	Example Component	Why A1070 Is Used
Electrical	Bus bars, conductors, foils	High electrical conductivity and good formability
Chemical processing	Linings, tanks, fittings	Purity and corrosion resistance to many chemicals
Architecture	Decorative cladding, façades	Surface finish quality, formability, corrosion resistance
Consumer goods	Cookware, cookware components	Thermal conductivity and surface appearance
Electronics	Heat spreaders, EMI shields	High thermal/electrical conductivity and lightweight

A1070 is favored where a combination of purity, conductivity and formability enables reliable, low‑cost fabrication of complex shapes. The alloy’s ability to accept surface treatments such as anodizing and its consistent response in forming and joining operations make it a practical choice across multiple sectors.

Selection Insights

A1070 is an excellent choice when electrical or thermal conductivity and maximum formability are more important than peak mechanical strength; choose it for conductors, heat sink elements and deep‑drawn components. Compared with commercially pure aluminum grades like 1100, A1070 generally offers higher minimum purity and correspondingly slightly better conductivity at similar formability, trading negligible additional strength for improved conductive properties.

Compared with work‑hardened alloys such as 3003 or 5052, A1070 often provides superior electrical conductivity and sometimes better ductility, while 3003/5052 offer higher as‑worked strength and improved resistance to certain types of localized corrosion. Compared with heat‑treatable structural alloys like 6061 or 6063, A1070 is chosen when formability, conductivity, corrosion performance and lower cost outweigh the need for higher peak strengths achievable in precipitation‑hardened alloys.

When deciding, weigh conductivity, formability and surface finish priorities against strength requirements and availability; specify O temper for complex forming and H‑tempers when incremental cold‑work strength is needed, and confirm standard limits for conductivity and impurities for critical electrical or chemical service.

Closing Summary

A1070 remains relevant because it combines very high aluminum purity with excellent formability, thermal and electrical conductivity, and consistent corrosion performance, making it ideal for applications where these attributes are prioritized over high mechanical strength. Its predictable behavior in forming, joining and surface finishing keeps it a widely used material in electrical, chemical, architectural and thermal management applications.