Aluminum 8092: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

8092 is an aluminum alloy categorized in the 8xxx series, a family that traditionally contains elements outside the classic 1xxx–7xxx designations and often includes lithium and other specialty additions. Its chemistry and development position it as an Al-Li based, heat-treatable alloy that leverages lithium to reduce density and increase elastic modulus relative to conventional aluminium grades.

The major alloying elements include lithium as the density- and stiffness-modifying element, with secondary amounts of magnesium, copper and trace zirconium or titanium for grain control and precipitation strengthening. The primary strengthening mechanism is precipitation hardening following solution treatment and artificial aging, with contributions from fine Li-containing phases (such as δ′/Al3Li) and conventional Al-Cu/Mg precipitates when present.

Key traits include an elevated specific strength and improved stiffness for a given mass fraction, competitive corrosion resistance when properly treated and coated, and reasonable formability in softer tempers with diminished ductility in peak-aged conditions. Weldability is generally acceptable with appropriate filler alloys and post-weld treatments, while care is required to manage hot-cracking and HAZ softening.

Typical industries adopting 8092 are aerospace structures and fittings, high-performance transport components, and selective marine and defense applications where weight savings and stiffness are critical. Engineers select 8092 over other alloys when a combination of reduced density, higher modulus, and heat-treatable peak strength outweigh the higher alloy cost and processing complexity.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High (18–28%)	Excellent	Excellent	Fully annealed, max ductility for forming
T4	Medium	Medium (12–18%)	Good	Good	Natural aged after solution treatment
T6 / T7	High	Low–Medium (6–12%)	Moderate	Moderate	Solution treated and artificially aged for peak strength
T8	High (similar to T6)	Low (6–10%)	Moderate	Moderate	Cold-worked, then artificially aged for tailored properties
T351 / T651	High	Low–Medium (6–12%)	Moderate	Moderate	Stress-relieved tempers for structural components
H14	Medium	Low–Medium (10–15%)	Good for moderate forming	Good	Work-hardened for moderate strength without heat treatment

Temper has a strong influence on the balance between strength and ductility in 8092, with annealed O condition optimized for forming and T6/T8 for structural strength. Post-weld and thermal exposure can move the local microstructure toward softer or embrittled states, so temper selection must account for downstream joining and service thermal history.

Chemical Composition

Element	% Range	Notes
Li	0.8 – 2.0	Primary lightweighting and modulus element; controls density and δ′ precipitation
Mg	0.3 – 1.2	Promotes age-hardening with Al-Li; improves strength and strain hardening
Cu	0.1 – 0.8	Enhances precipitation strengthening; can affect corrosion if high
Zn	0.05 – 0.4	Minor; can contribute to strength but monitored to limit stress corrosion
Zr	0.02 – 0.25	Grain refiner and dispersoid former to control recrystallization and texture
Ti	0.01 – 0.12	Nucleant for grain structure during solidification and thermomechanical processing
Fe	≤ 0.50	Impurity element; excessive Fe reduces toughness and can form intermetallics
Si	≤ 0.50	Controlled level to reduce coarse phases; high Si can degrade properties
Mn	≤ 0.20	Minor addition to control grain boundary phases and recrystallization
Others	Balance Al	Trace elements and residuals; balance is aluminium matrix

The lithium fraction is the primary driver of 8092 performance, reducing density and enabling δ′/Al3Li precipitates that raise modulus and yield strength. Secondary alloying elements such as Mg and Cu tailor the precipitation sequence and achievable strength; Zr and Ti are included in small amounts to pin grain boundaries and suppress recrystallization during processing.

Mechanical Properties

In tensile behavior 8092 shows a marked change between annealed and peak-aged tempers. In soft O or mildly aged conditions the alloy exhibits substantial elongation and ductility suitable for complex forming operations, while peak-aged T6/T8 conditions trade ductility for elevated yield and tensile strength through a dense distribution of nanoscale precipitates. Fatigue performance is generally favourable for Al-Li alloys due to higher modulus and lower density, but fatigue crack initiation can be sensitive to surface condition and microstructural heterogeneities.

Yield strength rises significantly after solution treatment and artificial aging, often achieving design-level static strengths competitive with some 7xxx series alloys but with lower density and improved stiffness-to-weight. Hardness correlates well with tensile properties and can be monitored as a process control metric after aging. Thickness and form factor affect aging kinetics and cold-work response—thicker sections show slower homogenization and may require extended solution treatment to fully dissolve coarse phases.

Property	O/Annealed	Key Temper (e.g., T6/T8)	Notes
Tensile Strength	220–280 MPa	380–470 MPa	Peak-strength depends on Li and Cu/Mg levels and aging schedule
Yield Strength	110–160 MPa	320–400 MPa	Offset yield depends on precipitate distribution and cold work
Elongation	18–28%	6–12%	Ductility reduced at peak aging; fracture mode transitions from ductile to mixed
Hardness	40–55 HB	95–140 HB	Hardness reflects age-hardening; values are process-and-thickness dependent

Physical Properties

Property	Value	Notes
Density	~2.60–2.65 g/cm³	Approximately 3–6% lower than conventional Al alloys, depending on Li content
Melting Range	~505–655 °C	Solidus/liquidus shift with alloying; solution treatments typically 510–540 °C depending on section
Thermal Conductivity	~140–170 W/m·K	Lower than pure Al; decreased by Li and alloying additions
Electrical Conductivity	~30–45 % IACS	Reduced compared with pure Al due to solute scattering from Li, Cu and Mg
Specific Heat	~880–920 J/kg·K	Typical for Al alloys; varies modestly with composition
Thermal Expansion	~23–25 ×10⁻⁶ /K	Slightly reduced compared to many Al alloys due to Li additions lowering CTE

Lower density and increased modulus are the salient physical advantages of 8092, improving specific stiffness and making the alloy attractive where mass reduction is a primary driver. Thermal properties are intermediate—thermal conductivity and electrical conductivity are reduced compared with high-purity aluminium, which influences design of heat-dissipating components and electromagnetic considerations.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.3–6.0 mm	Good recovery of properties after heat treatment; thinner gauges age uniformly	O, T4, T6, T8	Common for aerospace panels and formed components
Plate	6–50 mm	Slower homogenization and longer solution times; potential for HAZ softening in welded structures	T6, T651	Used in structural members where thickness increases load capacity
Extrusion	Profiles up to several hundred mm	Extrudability depends on billet grain structure; post-extrusion aging yields design strength	O, T6, T8	Complex cross-sections for frames and stiffeners
Tube	OD 6–150 mm	Wall thickness affects quench and aging; tubing for structural and fluid systems	O, T6	Requires careful process control to avoid anisotropy
Bar/Rod	Diameters up to 150 mm	Bars maintain homogeneous properties when homogenized correctly	O, T6	Stock for machining fittings and connectors

Sheets and extrusions are the most common product forms for 8092, given the alloy's use in panels, frames and fittings where both formed shapes and high strength-to-weight are needed. Plates and thick sections require adjusted thermal cycles to ensure full solutioning, while extrusions benefit from controlled grain refinement to permit subsequent heat treatment without excessive recrystallization.

Equivalent Grades

Standard	Grade	Region	Notes
AA	8092	USA	Industry designation for the alloy; used in aerospace specifications
EN AW	Al‑8092 (approx.)	Europe	No exact EN equivalent in common catalogs; European suppliers often list as Al‑Li specialty alloys
JIS	A8092 (approx.)	Japan	Japanese standards may classify under Al-Li specialty families with local designations
GB/T	8092 (approx.)	China	Chinese standards for enhanced Al-Li alloys exist but compositional tolerances can vary

Direct one-to-one equivalents for 8092 are uncommon because 8xxx-series alloys are frequently proprietary or developed to specific specifications for aerospace and defense primes. Regional standards may allow close matches but users must verify critical chemistry and mechanical property requirements rather than relying solely on nominal grade numbers.

Corrosion Resistance

Atmospheric corrosion resistance of 8092 is generally good when compared to highly alloyed 2xxx series Al-Cu alloys, provided that copper levels are controlled and suitable surface treatments are applied. In marine and chloride-rich environments the presence of Li and Cu necessitates protective coatings, anodizing, or cathodic protection to avoid localized pitting and accelerated general corrosion.

Stress corrosion cracking susceptibility is lower than high-copper 2xxx alloys but can be higher than simple wrought 5xxx Mg-bearing alloys under certain temper and stress states. The formation of edge and weld-related microstructural heterogeneities can be sites for SCC initiation, so design should minimize tensile residual stresses and use appropriate temper and post-weld aging.

Galvanic interactions with common structural materials require consideration: 8092 is more anodic than stainless steels and less noble than many high-purity aluminium alloys, so insulating layers or compatible fasteners are recommended in mixed-metal assemblies. Overall, 8092 offers a favorable corrosion-resistance-to-strength balance compared with many heat-treatable alloys, but surface finishing and metallurgical control are critical for long-term service.

Fabrication Properties

Weldability

8092 is weldable by conventional fusion processes such as TIG and MIG when prequalified welding parameters and filler alloys are used. Recommended filler alloys are typically Al-Cu-Mg or Al-Mg fillers formulated to maintain ductility and minimize hot-cracking risk; use fillers that restore acceptable corrosion resistance in the weld and HAZ. Post-weld aging or mechanical stress relief is often required to recover strength lost to HAZ softening, and welds need to be qualified for SCC and fatigue resistance in service conditions.

Machinability

Machinability of 8092 is moderate and generally comparable to other Al-Li heat-treatable alloys, with good chip breaking when using carbide or high-speed steel tooling. Cutting speeds should be optimized for hardness of the temper; peak-aged material benefits from slower feeds and rigid fixturing. Tool coatings such as TiAlN extend tool life when machining aged tempers, and flood coolant helps manage built-up edge that can occur with fine, strong precipitate distributions.

Formability

Formability is best in the O and T4 tempers where ductility allows relatively tight bend radii and complex stamping operations with minimal cracking. For peak-aged tempers forming is constrained by reduced elongation; processes typically use pre-forming in softer tempers followed by solution heat treatment and controlled aging to achieve final strength and dimensional stability. Minimum bend radii depend on gauge and temper but are generally larger in T6/T8 conditions—planning for springback and fracture risk is essential in tooling design.

Heat Treatment Behavior

As a heat-treatable Al-Li alloy, 8092 responds to conventional solution treatment, quenching and artificial aging sequences to develop high strength. Typical solution treatments are conducted at temperatures sufficient to dissolve Li- and Cu/Mg-bearing phases followed by rapid quenching to retain a supersaturated solid solution. Artificial aging at controlled temperatures promotes the precipitation of δ′ (Al3Li) and other strengthening phases; aging schedules can be tuned to prioritize peak strength (T6) or improved fracture toughness and overage stability (T7-like conditions).

Temper transitions such as T4 to T6 are predictable, but care must be taken with section thickness and cooling rates as inhomogeneous quench rates will produce variable precipitation and mechanical response. If applicable, cold work prior to aging (T8) can increase yield strength through dislocation-assisted precipitation kinetics, but this can compromise ductility and formability and must be balanced by process simulation and mechanical testing.

High-Temperature Performance

Long-term exposure to elevated temperatures progressively reduces the strength of 8092 as stable precipitates coarsen and δ′ dissolves or transforms, with notable strength loss above ~120–150 °C. Short-term exposure to higher temperatures, for welding or brazing, creates a softened HAZ that can reduce service life under cyclic loading unless post-thermal treatments are applied. Oxidation rates at typical service temperatures are low for aluminium alloys, but surface films can change chemical passivity and influence corrosion interactions in elevated-temperature, humid, or marine environments.

For sustained elevated-temperature service consider alternate alloys specifically designed for high-temperature stability, or design with safety factors for the degradation in yield and fatigue strength that accompanies temper relaxation and coarsening.

Applications

Industry	Example Component	Why 8092 Is Used
Aerospace	Fuselage stiffeners, bulkhead fittings	High specific strength and stiffness reduces mass while meeting structural loads
Marine	Lightweight deck structures and fittings	Lower density and good corrosion performance with coatings provide weight savings
Defense/Transport	Vehicle armor mounts, railcars components	Balance of strength, stiffness and manufacturability for weight-sensitive systems
Electronics	Structural chassis and moderate heat spreaders	Good thermal conductivity for structural parts and acceptable EMI behavior

8092 is chosen where a step-change in weight-sensitive stiffness and strength is needed without the higher cost or embrittlement risks of some high-strength 7xxx alloys. Its combination of reduced density, heat-treatable strength, and reasonable corrosion resistance makes it a niche but important alloy for modern lightweight structural components.

Selection Insights

For engineers choosing between grades, 8092 trades higher strength and lower density for somewhat reduced electrical conductivity and a higher alloy cost compared with commercially pure aluminum like 1100. Use 8092 where stiffness-to-weight and peak structural strength are priorities and where conductivity is a secondary concern.

Compared with work-hardened alloys such as 3003 or 5052, 8092 offers a higher achievable strength after heat treatment while maintaining competitive corrosion resistance when properly processed; select 8092 when strength and stiffness need to exceed what Mg-bearing non-heat-treatable alloys can supply.

Compared with common heat-treatable alloys such as 6061, 8092 provides better specific stiffness and potential mass savings despite sometimes lower absolute peak tensile values; prefer 8092 when weight reduction and modulus improvement outweigh the convenience and ubiquity of 6xxx alloys.

Closing Summary

8092 remains relevant as a specialized Al-Li heat-treatable alloy delivering improved specific stiffness and competitive strength for weight-sensitive engineering applications, provided designers account for its alloying-driven trade-offs in conductivity, cost and processing complexity.