Aluminum 1350: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

1350 is a member of the 1xxx aluminum series, representing the commercially pure aluminum family with nominal minimum aluminum content around 99.5%. This series is characterized by very low alloying additions and is distinct from the 3xxx, 5xxx and 6xxx families that rely on Mn, Mg or Mg+Si for strengthening.

The primary alloying elements in 1350 are trace impurities and controlled residuals such as iron, silicon and very small amounts of manganese or titanium; these are kept low to preserve electrical and thermal conductivity. Strengthening in 1350 is accomplished almost exclusively through work‑hardening (strain hardening) rather than by heat treatment, and softening is achieved by annealing and recrystallization.

Key traits of 1350 include very high electrical and thermal conductivity for an alloy, good corrosion resistance in atmospheric environments, excellent formability in annealed tempers, and generally easy weldability using conventional fusion processes. Typical industries using 1350 are electrical power distribution (conductors, busbars), electronics (shims, foils, heat spreaders), architectural elements and some lightweight structural applications where conductivity and formability are prioritized over peak strength.

Engineers select 1350 when the design driver is combination of electrical conductivity, good surface finish, and ease of forming or welding rather than highest strength; it is chosen over higher‑alloyed or heat‑treatable aluminum grades when conductivity, corrosion resistance and cost are dominant factors. Its relative purity also simplifies joining and surface finishing for electrical and reflective components.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Fully annealed condition; maximum ductility and conductivity
H12	Low-Mid	Moderate	Very good	Excellent	Quarter hard; light work‑strengthening
H14	Mid	Low-Moderate	Good	Excellent	Half hard; common for conductor strip and some formed parts
H16	Mid-High	Low	Fair-Good	Excellent	Three‑quarter hard; used when more yield is required
H18	High	Low	Limited	Excellent	Full hard; best strength from cold work but lowest formability
T4 (not applicable)	—	—	—	—	1xxx alloys are not heat‑treatable; T tempers are rare and limited to processing definitions
T5/T6/T651	—	—	—	—	Heat‑treatable tempers are not applicable for 1xxx series; listed for reference only

Temper significantly controls the mechanical and forming behavior of 1350 because the alloy does not respond to age hardening; all practical strengthening comes from strain hardening. Choosing an O temper maximizes ductility and conductivity for deep drawing and tight bends, while H‑tempers trade formability for higher yield and tensile strength useful in structural strip, busbars and rigid formed components.

Chemical Composition

Element	% Range	Notes
Si	≤ 0.25	Controlled to maintain conductivity and minimize intermetallics
Fe	≤ 0.60	Principal impurity; higher Fe reduces conductivity and can affect formability
Mn	≤ 0.05	Small amounts can slightly increase strength; kept low in 1350
Mg	≤ 0.05	Minimal; magnesium not used for strengthening in this grade
Cu	≤ 0.05	Kept very low to preserve corrosion resistance and conductivity
Zn	≤ 0.05	Minimal, controlled to avoid galvanic concerns and brittleness
Cr	≤ 0.05	Trace levels; not a deliberate alloying element for this grade
Ti	≤ 0.03	Deoxidizer and grain refiner in some ingot practices
Others	≤ 0.15 total	Residuals and trace elements; Al balance (~99.5% min)

The near‑purity chemistry is optimized to deliver high electrical and thermal conductivity while keeping intermetallic precipitates and second‑phase particles to a minimum. Small amounts of iron and silicon are tolerated as processing residuals, but designers must account for their effect on conductivity, surface finish and deep‑draw response.

Mechanical Properties

In tensile behavior 1350 exhibits low yield strength in the annealed O condition and progressively higher yield and ultimate strength with increasing work hardening (H‑tempers). Elongation in the O condition is high, enabling deep drawing and severe forming operations; however elongation falls sharply as temper moves toward H18 where the material is substantially strengthened by cold work.

Hardness correlates with temper: annealed material measures low hardness typical of pure aluminum while fully strain‑hardened conditions approach values suitable for light structural loads and rigid strips. Fatigue resistance for 1350 is moderate compared with higher‑alloyed aluminum grades and is influenced by surface quality, residual stress from forming and the presence of notches or welds.

Thickness affects formability and strength; thin gauges are easier to cold‑work to higher hardness levels but may also suffer from edge cracking if improperly processed. Thicker sections maintain higher through‑thickness ductility in annealed condition but require greater force and larger tooling radii for forming.

Property	O/Annealed	Key Temper (e.g., H14)	Notes
Tensile Strength	~60–110 MPa	~120–160 MPa	Tensile increases with work hardening; values are temper and gauge dependent
Yield Strength	~20–50 MPa	~100–140 MPa	Yield rises markedly with H‑tempers; annealed yield is low
Elongation	~30–40%	~5–15%	Elongation drops as temper is increased; sheet thickness also influences values
Hardness	~20–35 HB	~35–55 HB	Hardness roughly follows cold work level; higher hardness reduces formability

Physical Properties

Property	Value	Notes
Density	2.69 g/cm³	Typical for aluminum alloys; useful for mass and stiffness calculations
Melting Range	~660 °C (solidus ≈ 660 °C)	Near pure aluminum melting point; narrow melting range
Thermal Conductivity	~215–235 W/m·K	High for an alloy; varies with impurity content and temper
Electrical Conductivity	~57–62 %IACS	High conductivity makes 1350 attractive for conductors and busbars
Specific Heat	~900 J/kg·K	Typical aluminum specific heat used in thermal analyses
Thermal Expansion	~23–24 µm/m·K (20–100 °C)	Coefficient important for bonded assemblies and thermal cycling design

The physical property set emphasizes heat and charge transport: thermal conductivity and electrical conductivity values are high relative to most structural alloys, which makes 1350 well suited for electrical and thermal management applications. The combination of low density and good thermal properties allows designers to exploit mass and heat‑sinking advantages in electronics and power systems.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.2–6.0 mm	Soft in O; strengthened by cold roll to H‑tempers	O, H12, H14, H16	Widely used for reflectors, capacitor foils, and heat spreaders
Plate	>6.0 mm	Similar trends but thicker sections retain ductility longer	O, H12	Less common; used where thicker conductors are required
Extrusion	Profiles up to large cross‑sections	Extruded parts generally start soft then are cold worked	O, H14	Cross‑section complexity can be moderate due to high ductility
Tube	0.5–10 mm wall	Behavior mirrors sheet for thin‑wall; formability matters for bends	O, H14	Common for bus duct and conduit where conductivity is needed
Bar/Rod	Diameters 2–50 mm	Cold swaged for strength; low alloying limits hardening range	O, H18	Used for electrical terminals and machined components

Processing differences between forms affect mechanical properties: sheet and thin strip are readily cold‑worked to H‑tempers with predictable increases in strength, whereas thicker plate and bar often require more aggressive forming or machining. Extrusions and tubes allow complex geometries while preserving the alloy’s conductivity advantages, and product selection should match tempering and required forming operations to component geometry.

Equivalent Grades

Standard	Grade	Region	Notes
AA	1350	USA	Industry designation for this specific 1xxx commercial alloy
EN AW	Al99.5 (approx.)	Europe	Equivalent falls into commercially pure Al classifications; spec varies by EN standard
JIS	A1050 / A1070 (approx.)	Japan	JIS 1xxx family equivalents; exact chemistry and tempers differ slightly
GB/T	Al99.5 (approx.)	China	Mapped to commercially pure Al grades in Chinese standards

Direct one‑to‑one equivalents are often represented as “commercially pure” or Al99.5 family grades in regional standards, but exact impurity limits, permitted minor elements and temper definitions vary by standard organization. Engineers should consult the specific standard sheet and supplier certification to confirm electrical conductivity, impurity caps and permitted tempers when substituting between regional equivalents.

Corrosion Resistance

1350 exhibits good natural atmospheric corrosion resistance because of its high aluminum content and minimal active alloying elements. In normal urban and industrial atmospheres the naturally forming oxide film provides effective protection, and the alloy performs well in painted or anodized finishes when surface appearance is important.

In marine environments the alloy has reasonable resistance to general corrosion but is susceptible to localized attack if chloride concentrations are high and crevice conditions exist; anodizing or protective coatings are common mitigations. Stress corrosion cracking is not a typical failure mode for low‑alloy 1xxx series aluminum because the alloy lacks the precipitate structures that promote classic SCC in some high‑strength alloys.

Galvanic interactions must be considered when 1350 is paired with more noble metals such as copper or stainless steel; as a relatively active metal it will corrode preferentially when electrically connected in an electrolyte. Compared with 5xxx and 6xxx family alloys, 1350 sacrifices some strength but generally provides equal or superior corrosion resistance in many atmospheres due to its purity and the absence of galvanic‑promoting alloy phases.

Fabrication Properties

Weldability

1350 is readily welded by common fusion methods such as TIG and MIG due to its high aluminum content and lack of hardening precipitates. Recommended practice uses similar‑composition filler alloys (for example ER4043 or ER1100 where electrical conductivity is critical) to balance mechanical and electrical properties; filler choice depends on whether conductivity or joint strength is prioritized. Hot‑cracking risk is low compared with higher Cu or Mg alloys, but attention to joint design, contamination and oxide removal is important to avoid porosity and poor fusion. Heat‑affected zone softening is not a concern in the same way as for heat‑treatable alloys, because the alloy is non‑heat‑treatable and mechanical properties are controlled by cold work.

Machinability

Machinability of 1350 is fair to moderate; because the alloy is relatively soft, it tends to produce long, continuous chips and can gall with inappropriate tooling or feeds. Carbide tooling with positive rake and chip‑breaking geometries is recommended for high‑productivity machining, and cutting speeds should be moderate to avoid built‑up edge. Surface finish achievable is good, but attention to clamping and part rigidity is necessary to prevent chatter in thin or long sections.

Formability

Formability of 1350 in the annealed O condition is excellent for deep drawing, bending and stretch forming, and it is commonly used where tight radii and complex shapes are required. Bend radii can be relatively small in O temper, often down to a few times material thickness depending on tooling and surface lubrication; in H‑tempers recommended minimum bend radius increases significantly. Cold working raises strength but decreases formability; designers should choose the softest practical temper for severe forming and plan final tempering or mechanical strengthening after forming where needed.

Heat Treatment Behavior

As a 1xxx series alloy, 1350 is non‑heat‑treatable in the sense of precipitation hardening; manipulation of mechanical properties is achieved through cold work and annealing. Annealing of 1350 promotes recovery and recrystallization; full anneal cycles are typically carried out in the 300–400 °C range depending on cross‑section and processing to restore ductility and conductivity.

There are no meaningful solution treatment and aging cycles for 1350 because it lacks the alloying elements required to form strengthening precipitates; therefore T‑temper classifications associated with age hardening do not apply. Work hardening is the primary strengthening mechanism: careful control of rolling, drawing and swaging parameters determines the final strength and ductility balance of produced parts.

High-Temperature Performance

1350 maintains metallic integrity to temperatures below about 150–200 °C, but will show progressive strength loss and creep tendency at elevated temperatures compared to higher‑strength alloys. In continuous service near or above 150 °C designers must account for reduced yield and increased thermal softening; thermal cycling can also coarsen grain structure and change surface oxide characteristics. Oxidation in air is limited to formation of the protective oxide film typical of aluminum, but prolonged exposure at elevated temperature can affect surface finish and electrical contact resistance.

In welding and brazing operations the heat‑affected zone does not produce the same over‑aging or precipitate dissolution seen in heat‑treatable alloys, but local annealing will reduce cold‑work induced strength adjacent to welds. For high‑temperature structural needs or where creep resistance is critical, engineers should consider heat‑resistant alloys outside the 1xxx family.

Applications

Industry	Example Component	Why 1350 Is Used
Electrical/Power	Overhead conductor strands, busbars, connectors	High electrical conductivity and good formability for conductor shaping
Electronics	Heat spreaders, foil, shielding	High thermal conductivity and excellent surface finish
Architecture	Roofing trim, reflectors	Corrosion resistance and aesthetic finishability
Automotive	Non‑structural conductive strips, reflectors	Good formability, conductivity and low cost
Marine	Non‑critical fittings, trim	Corrosion resistance in atmospheric marine environments

1350 is widely used where electrical or thermal performance and formability outweigh requirements for high strength; these application traits make it an economical choice for conductor components, thermal management parts and decorative architectural elements. Its combination of low cost, ready availability and compatibility with common joining and finishing methods keeps it relevant in modern production environments.

Selection Insights

For designs prioritizing conductivity and formability over peak strength, 1350 is a logical choice because it delivers high electrical and thermal conductivity with excellent ductility in annealed condition. When comparing to commercially pure 1100, 1350 often provides similar conductivity with modestly higher mechanical properties and slightly different impurity limits, trading very slight reductions in formability for improved stiffening in some tempers.

Compared with work‑hardened alloys such as 3003 or 5052, 1350 typically offers better electrical conductivity and comparable atmospheric corrosion resistance, but falls behind in achievable strength without significant cold work. Against heat‑treatable alloys like 6061 or 6063, 1350 will not reach their peak strength or stiffness, yet it is preferred when conductivity, formability, surface finish and cost are more important than maximum mechanical performance.

Use 1350 when electrical or thermal requirements, ease of forming and cost/availability drive material selection; choose H‑tempers only when additional cold work strength is needed, and specify O temper for deep drawing, tight bends and maximum conductivity.

Closing Summary

1350 remains a practical and widely used commercial‑purity aluminum because it combines high electrical and thermal conductivity with excellent formability, corrosion resistance and ease of fabrication, making it a first choice for conductors, heat‑management components and formed architectural parts where peak strength is not the primary design driver.