Aluminum A136: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

A136 is positioned within the 1xxx series of wrought aluminum alloys and is best described as a commercially-pure, micro-alloyed grade optimized for high formability and corrosion resistance with modest strength. The nominal chemistry is dominated by aluminum (>99 wt%), with deliberate trace concentrations of silicon, iron, copper and titanium to stabilize grain structure and improve mechanical consistency without changing the fundamental non-heat-treatable nature of the base metal. Strengthening is achieved primarily through work hardening (strain hardening) and microalloy control rather than precipitation hardening; it is not a heat-treatable alloy in the conventional T6 sense.

Key traits of A136 include excellent formability, high electrical and thermal conductivity relative to more heavily alloyed grades, and superior atmospheric corrosion resistance due to a stable native oxide film. Weldability is straightforward for common fusion processes, and machinability is moderate—better than many 5xxx/6xxx alloys when in the annealed condition but reduced after significant strain hardening. Typical industries using A136 include architectural and building products, pressure-tight housings, electrical conductors and busbars, decorative and formed panels, and lightweight enclosures where forming and corrosion performance trump high strength.

Engineers choose A136 over higher-strength alloys when design priorities emphasize deep drawability, conductivity, surface finish, and resistance to general corrosion rather than maximum structural strength. The alloy is often selected as a cost-effective, easy-to-fabricate material for parts that require complex stamping, tight surface aesthetics, or service in mildly corrosive atmospheres where the expense and weight of higher-strength, heat-treatable alloys are not justified.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High (30–50%)	Excellent	Excellent	Fully annealed, maximum ductility and conductivity
H12	Low-Medium	Medium-High (20–35%)	Very good	Excellent	Partial strain hardening, retains good formability
H14	Medium	Medium (10–25%)	Good	Excellent	Light work-hardening for improved strength
H16	Medium-High	Lower (6–15%)	Fair	Excellent	Stronger cold-worked temper, reduced stretch-formability
H18	High (cold-worked)	Low (3–8%)	Limited	Excellent	Heavily strain-hardened for maximum room-temperature strength

The temper selected for A136 directly controls the trade-off between strength and ductility because the alloy is non-heat-treatable. Moving from O to H18 progressively increases tensile and yield strength through deformation-induced dislocation density while reducing elongation and stretchability. Welded regions typically revert toward softer conditions in the heat-affected zone, so designers should account for local softening when specifying tempers for formed-and-then-welded assemblies.

Chemical Composition

Element	% Range	Notes
Al	Balance (~99.0–99.9)	Dominant element; provides conductivity and corrosion resistance
Si	0.05–0.25	Controlled to improve fluidity in cast variants and limit brittle intermetallics
Fe	0.05–0.8	Residual impurity; higher Fe increases strength slightly but can reduce ductility
Mn	≤0.05	Minimal; added only in trace amounts to control grain structure
Mg	≤0.05	Kept low to avoid precipitation strengthening; maintains conductivity
Cu	≤0.05	Very low to preserve corrosion resistance and conductivity
Zn	≤0.1	Kept minimal to avoid susceptibility to stress-corrosion phenomena
Cr	≤0.05	Trace additions for control of recrystallization in some product forms
Ti	≤0.03	Grain refiner in cast or cast-and-worked product variants
Others (including residuals)	≤0.15	Includes trace elements such as Ni, Pb, Bi; controlled for processing consistency

The chemical balance emphasizes aluminum with tightly controlled impurity and microalloy levels to maintain the 1xxx-series behavioral envelope. Small Si and Fe contents help stabilize processing and reduce the propensity for gross grain growth during thermomechanical steps, while limiting Mg, Cu and Zn prevents the alloy from behaving like a heat-treatable composition. Trace Ti or Cr can be used in some product forms to refine grain size and improve mechanical uniformity without substantially affecting conductivity.

Mechanical Properties

A136 exhibits tensile behavior typical of commercially-pure aluminum: relatively low yield and ultimate tensile strengths in the annealed condition combined with high uniform elongation and pronounced work-hardening capability. In the annealed (O) condition, the stress–strain curve is ductile with a long plastic region, allowing deep drawing and complex cold forming. As the material is strain-hardened to H-series tempers, yield and ultimate strengths rise while elongation and energy absorption fall; fracture tends to become more localized.

Hardness in A136 follows the same pattern: low Brinell or Vickers values in O condition and progressive increases with cold work. Fatigue performance is dependent on surface finish, residual stresses from forming, and the presence of notches; polished, strain-hardened parts often show improved fatigue initiation life compared with rough-formed components. Thickness effects are significant for forming and strength—thin gauges attain higher formability and lower bending springback, while thicker gauges show higher absolute stiffness but reduced deep-drawability.

Property	O/Annealed	Key Temper (e.g., H14)	Notes
Tensile Strength	60–120 MPa	110–170 MPa	Range depends on precise composition and cold work level
Yield Strength	20–60 MPa	60–130 MPa	Yield rises markedly with moderate strain hardening
Elongation	30–50%	10–25%	Ductility decreases with increasing cold work
Hardness	15–35 HB	25–55 HB	Hardness correlates with work-hardening and affects machinability

Physical Properties

Property	Value	Notes
Density	~2.70 g/cm³	Typical of aluminum; good specific strength when alloyed or cold-worked
Melting Range	~660–657 °C	Single-phase aluminum melting range; solidus/liquidus are close
Thermal Conductivity	~200–235 W/(m·K)	High, depending on purity; slightly reduced by alloying and cold work
Electrical Conductivity	~55–65% IACS	High relative to alloyed series; annealed condition near upper range
Specific Heat	~0.90 J/(g·K)	High specific heat useful for thermal buffering
Thermal Expansion	~23–24 µm/m·K	Typical isotropic expansion; consider for tight-tolerance assemblies

A136’s high thermal and electrical conductivities are useful in heat-sinking and conductor applications, and these properties scale inversely with alloying and work-hardening. Density gives a favorable strength-to-weight ratio for formed enclosures and conductive busbars, and the relatively low melting range simplifies welding processes but also constrains high-temperature service limits.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.2–6.0 mm	Consistent; best formability in thin gauges	O, H12, H14	Widely used for deep drawing and decorative panels
Plate	6–25 mm	Higher stiffness; limited deep-drawability	O, H16	Used where thicker sections are required, often machined after forming
Extrusion	Wall thickness 1–20 mm	Mechanical properties can vary with section thickness	O, H14, H16	Complex profiles for architectural trim and enclosures
Tube	OD 6–200 mm	Strength depends on wall thickness and cold work	O, H14	Drawn or welded tubes for lightweight frameworks and conduits
Bar/Rod	DIA 3–50 mm	Strength increases with cold drawing	O, H16	Used for connectors, pins, and machined components

Processing differences drive application selection: sheet forms are optimized for stamping and roll-forming, while extrusions allow complex cross-sections but may require post-extrusion aging control and straightening. Plate provides structural stiffness but reduces the available forming operations. Welded tubes and extrusions can be produced with minimal post-process distortion if temper selection and fixturing are controlled.

Equivalent Grades

Standard	Grade	Region	Notes
AA	A136	USA	Proprietary or lesser-common wrought grade in the AA 1xxx family
EN AW	1050A / 1070	Europe	Closest equivalents in widely specified European standards for high-purity Al
JIS	A1050 / A1070	Japan	Similar commercially-pure designations with high formability
GB/T	Al99.5 / Al99.7	China	Common commercial-purity equivalents in Chinese standards

Equivalent grades across standards differ primarily in minimum aluminum content and tightly controlled impurity limits; EN/JIS/GB variants supply slightly different mechanical baselines and certified impurity ceilings. When substituting, engineers must verify conductivity, temper designation crosswalks, and supplier-specific cast-and-worked processing histories to ensure equivalent formability and surface quality. Certification and mill test reports are recommended when tight conductivity or surface aesthetics are required.

Corrosion Resistance

A136 demonstrates excellent general atmospheric corrosion resistance because of a continuous, self-healing aluminum oxide (Al2O3) film that rapidly reforms after mechanical damage. In neutral and mildly industrial atmospheres the alloy survives with minimal uniform attack, and typical painted or anodized finishes further extend life in architectural applications. In marine environments the alloy performs well for many applications, but concentrated chloride exposure and spray zones can induce pitting and crevice corrosion; design choices such as sacrificial coatings, anodizing, and careful detailing are necessary for long-term performance.

Stress corrosion cracking susceptibility is low for A136 compared with 2xxx and 7xxx series alloys because of the low levels of copper and zinc; however, welded or highly cold-worked areas with tensile residual stresses require attention to avoid localized failures in aggressive environments. Galvanic interactions must be considered when coupling A136 to more noble alloys or stainless steel: aluminum will act anodically and corrode preferentially unless electrically isolated or protected by coatings. Compared with 5xxx and 6xxx series alloys, A136 offers superior conductivity and formability with similar or slightly superior general corrosion resistance when alloying additions in the latter families are moderate.

Fabrication Properties

Weldability

A136 welds readily by TIG, MIG/GMAW and resistance spot welding when common aluminum practices are used, including proper joint design and pre-cleaning to remove surface oxides and oils. Filler metals in the 4xxx (Al-Si) or 5xxx (Al-Mg) families are commonly specified depending on desired post-weld corrosion performance and strength, with 4043 and 5356 being typical choices. Hot-cracking risk is low compared with high-alloy systems, but weld joint fit-up and thermal distortion control are important to avoid porosity and surface blemishes; the heat-affected zone will revert toward softer conditions, which must be considered in strength-critical designs.

Machinability

Machinability of A136 is moderate in the annealed state but decreases as the material is strain-hardened; overall it machines easier than many higher-alloyed series due to low work-hardening exponent and good chip formation characteristics. Carbide tooling and geometries designed for aluminum (e.g., positive rake, high helix) provide clean chips and good surface finish; typical cutting speeds are high relative to steels and coolant control is required to avoid smearing. For precision turning and milling, pre-anneal or using H12/H14 tempers can reduce tool loads and improve dimensional control.

Formability

Formability is a defining strength of A136: the annealed (O) temper enables small bend radii, deep drawing and complex stretch forming with low springback. Typical minimum bend radii in sheet depend on thickness and temper but can be as low as 1–1.5× thickness for O temper in simple bends; H14/H16 require larger radii and progressive forming steps. Cold-work response is predictable allowing staged forming; when severe forming is required, interim anneals restore ductility and mitigate cracking in tight radii or deep-draw cups.

Heat Treatment Behavior

Because A136 belongs to the non-heat-treatable 1xxx family, it does not respond to solution treatment and artificial aging intended to produce precipitation strengthening. Mechanical strength modifications are achieved by work hardening and recovery/anneal cycles. Full annealing (O) is used to maximize ductility and conductivity and typically involves heating to temperatures where recrystallization occurs (commonly in the range of 300–420 °C depending on product form) followed by controlled cooling.

For production control, intermediate anneals are often applied after significant cold deformation to restore formability; these are shorter duration processes at lower temperatures (e.g., 300–350 °C) tailored to part geometry and desired microstructure. Stabilization or stress-relief anneals are used selectively to reduce residual stresses before precision machining or to minimize distortion prior to final assembly.

High-Temperature Performance

A136 retains usable mechanical properties only up to modest elevated temperatures; tensile and yield strengths decline measurably above ~100 °C and are substantially reduced by 200–300 °C as recovery and softening progress. Oxidation at typical service temperatures is limited to the formation of the protective oxide film and is not a major failure mechanism for the temperature ranges commonly encountered in architectural and electrical applications. For continuous service beyond ~150 °C designers should validate creep resistance and dimensional stability since commercially-pure aluminum exhibits significant time-dependent deformation under sustained loads at elevated temperatures.

In welded assemblies, HAZ softening becomes more pronounced with increasing service temperature and repeated thermal cycling can lead to relaxation of the work-hardened condition. For components exposed to cyclical high heat, consider alternative alloys designed for elevated-temperature strength or apply mechanical design margins.

Applications

Industry	Example Component	Why A136 Is Used
Automotive	Decorative trim panels, emblems	High formability and surface finish
Marine	Non-structural housings, trim	Good corrosion resistance and light weight
Aerospace	Interior fittings, fairings	High conductivity and ease of forming for non-critical parts
Electronics	Heat sinks, EMI shields, busbars	Excellent thermal/electrical conductivity
Architecture	Cladding, soffits, facades	Anodizable surface and corrosion resistance

A136 is commonly selected where deep-drawing, visual quality, and conductivity are critical while structural loads are moderate. Its role is pronounced in formed exterior trim, conductive components, and furniture or equipment housings where post-processing such as anodizing or painting is required to achieve the final finish and environmental protection.

Selection Insights

Choose A136 when design priorities require maximum formability, high electrical/thermal conductivity, and superior surface quality at low to moderate strength levels. It is particularly cost-effective for high-volume deep-drawn parts and conductor applications where thermomechanical treatments are minimized.

Compared with commercially-pure aluminum (1100), A136 typically trades a small portion of conductivity and formability for tighter process control and slightly higher as-fabricated strength. Versus work-hardened alloys such as 3003 or 5052, A136 offers comparable or better formability and sometimes better conductivity, but 5xxx alloys will outperform A136 in structural strength and marine chloride resistance when higher Mg levels are acceptable. Compared with heat-treatable alloys like 6061 or 6063, A136 is preferred when forming, conductivity, surface finish, and cost are prioritized over maximum achievable peak strength.

Closing Summary

A136 remains a practical choice in modern engineering where the combination of exceptional formability, high conductivity, good corrosion resistance and low cost are more valuable than the absolute highest strength. Its predictable cold-working response, compatibility with common fabrication processes, and excellent surface finish potential keep it relevant across architecture, electronics, and light-assembly industries.