Aluminum 8017: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

8017 is an aluminum alloy that sits within the 8xxx series, a family dominated by lithium-bearing chemistries and other alloying strategies aimed at improving specific strength and stiffness. As an Al-Li derived alloy, 8017 uses lithium as a key alloying addition alongside controlled amounts of copper, magnesium and trace elements to optimize mechanical performance.

The primary strengthening mechanism in 8017 is precipitation hardening combined with a beneficiating reduction in density from lithium additions; precipitation of δ' (Al3Li) and other coherent phases during artificial aging produces a high strength-to-weight microstructure. Secondary strengthening contributions arise from grain refinement and possible cold-work in certain tempers, giving designers the option to balance ductility and strength through temper selection.

Key traits of 8017 include above-average specific strength and stiffness relative to conventional Al-Mg and Al-Mn alloys, competitive fatigue resistance, and a reduced density that benefits weight-sensitive applications. Corrosion resistance is generally good in atmospheric environments but can be sensitive to copper levels and heat treatment state; weldability is moderate and formability is temper-dependent.

Typical industries include aerospace primary and secondary structures, high-performance transportation components, and some high-strength marine and electronics structures where weight reduction is a priority. Engineers specify 8017 when the design must trade modestly lower absolute toughness and manufacturing complexity for a significant gain in specific strength and stiffness compared with 5xxx/3xxx alloys.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Fully annealed, maximum ductility and formability
H14	Medium	Medium	Good	Good	Strain-hardened to a controlled hardness for moderate strength
T4	Medium	Medium-High	Good	Good	Solution treated and naturally aged; good balance of ductility and strength
T6	High	Low-Medium	Fair	Moderate	Solution treated, quenched and artificially aged to peak strength
T8 / T651	Very High	Low	Limited	Moderate	Cold worked after solution treatment and aging (T8) or stress relieved after solution + artificial aging (T651)

Temper affects 8017 significantly because the Li-bearing precipitates responsible for strengthening are sensitive to time–temperature histories; solution treatment and aging sequences control the size, density and distribution of δ' and other precipitates. Cold work and strain hardening can supplement precipitation strengthening but reduce formability and change fatigue crack initiation behavior.

Chemical Composition

Element	% Range	Notes
Si	0.05–0.25	Controlled low silicon to limit brittle intermetallic formation and maintain weldability
Fe	0.20–0.60	Controlled impurity; excessive Fe forms intermetallic particles that reduce ductility
Mn	0.05–0.40	Controls recrystallization and grain structure for toughness and formability
Mg	0.20–0.80	Contributes to precipitation and solid-solution strengthening; interacts with Li/Cu phases
Cu	0.20–0.60	Promotes higher peak strength via Al–Cu–Li/T1-type phases but can reduce corrosion resistance
Zn	0.05–0.30	Minor; can assist strength in small amounts but high Zn is avoided to limit SCC risk
Cr	0.02–0.25	Microalloying element that stabilizes grain structure and limits recrystallization
Ti	0.02–0.15	Grain refiner for cast/extruded product and helps control eutectic particles
Others	Li 0.8–1.4; residuals balance Al	Lithium is the defining addition that lowers density and forms δ' (Al3Li) precipitates

The low but critical lithium content in 8017 tailors the density, elastic modulus and precipitation chemistry; it forms coherent δ' precipitates that provide strong age-hardening response. Copper and magnesium are tuned to produce reinforcing intermetallics without excessively compromising corrosion resistance, while microalloying additions such as Cr and Ti stabilize the microstructure during thermomechanical processing.

Mechanical Properties

Tensile behavior for 8017 varies strongly with temper: in the fully annealed condition the alloy shows moderate tensile and yield values with relatively high elongation, while peak-aged tempers develop a fine precipitate population that raises yield and ultimate strengths substantially but reduces total elongation. Yield to tensile ratios in peak-aged states are typical of heat-treatable aluminum alloys, and ductility is usually traded off for strength in high-strength tempers.

Hardness follows the same trend as tensile properties and is a reliable shop-floor metric for aging progression; hardness increases rapidly during artificial aging as δ' and other strengthening phases nucleate and coarsen. Fatigue performance of 8017 is often superior on a specific-strength basis relative to common 6xxx alloys owing to its higher stiffness and fine precipitate structure, but surface condition and residual stresses from forming/welding are critical for life predictions.

Thickness and product form influence achievable properties because diffusion distances during solution heat treatment and aging affect precipitate size and distribution; thin gauges reach full solutioning and homogenization faster than thick plates, which can exhibit gradients in properties and residual stresses after quenching.

Property	O/Annealed	Key Temper (T6)	Notes
Tensile Strength	150–220 MPa	350–470 MPa	T6 peak strength varies with exact composition and aging cycle
Yield Strength	70–120 MPa	300–420 MPa	Yield increases dramatically with aging and cold work
Elongation	15–22%	6–12%	Elongation drops as strength increases; gauge has a strong effect
Hardness	HB 40–55	HB 115–150	Hardness correlates with precipitate density and is used to control aging

Physical Properties

Property	Value	Notes
Density	~2.62 g/cm³	Reduced relative to pure Al (≈2.70 g/cm³) due to lithium additions; benefits specific stiffness
Melting Range	~555–645 °C	Solidus/liquidus vary slightly with alloying; standard Al heat treatment practice applies
Thermal Conductivity	~120–140 W/m·K	Lower than high-purity aluminum but still high relative to steels; decreases with alloying
Electrical Conductivity	~22–38 % IACS	Conductivity drops with increased alloy content and after aging due to precipitation
Specific Heat	~0.9 J/g·K	Typical for aluminium alloys, useful for thermal mass calculations
Thermal Expansion	~22–24 µm/m·K (20–100 °C)	Slightly lower than some Al alloys; Li reduces thermal expansion marginally

The reduced density of 8017 is a primary driver for its selection in weight-sensitive designs; engineers exploit the higher specific modulus to reduce structural mass. Thermal and electrical properties are adequate for heat-sinking and conductive structural components but must be balanced against the alloy's reduced conductivity compared with pure aluminum in electrical or thermal-critical applications.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.3–6.0 mm	Uniform through-thickness in thin gauge	O, T4, T6	Used for panels and formed skins; thin gauges age uniformly
Plate	6–50+ mm	Potential property gradients after heat treatment	T6, T651	Thick plates require careful solution treatment and quench control
Extrusion	Profiles up to 300 mm	Good directional strength; extrusion heat effects	T6 after aging	Complex cross-sections achievable; grain flow aids fatigue resistance
Tube	OD 6–150 mm	Similar to extrusions; wall thickness affects aging	O, T6	Used for high-strength structural tubing and hydraulic components
Bar/Rod	3–80 mm dia.	Good machinability in annealed, high strength in aged	O, H14, T6	Produced for fittings, fasteners and machined parts

Processing differences among product forms govern selection: sheet and thin extrusions can be rapidly solution treated and aged, while plate and heavy sections require longer soak times and more aggressive quench strategies to avoid residual microstructural gradients. Forming operations are most successful in annealed or naturally aged tempers; final aging often follows forming to regain required strength.

Equivalent Grades

Standard	Grade	Region	Notes
AA	8017	USA	Recognized as an 8xxx-series Al-Li alloy in manufacturer specifications
EN AW	Not standardized / approximate	Europe	No single direct EN equivalent; closest mapping is to high-strength Al-Li families in EN AW 8xxx variants
JIS	Not standardized	Japan	JIS equivalents are rare; bespoke specifications are common for aerospace users
GB/T	8017 / Al-Li series	China	Some Chinese standards reference Al-Li chemistry comparable to AA8017 in national catalogs

Equivalent grade mapping for Al-Li alloys like 8017 is not always direct because different standards set different maximum impurity limits and ageing requirements; manufacturers and specifiers frequently rely on certified chemistry and mechanical property tables rather than a single cross-reference. When substituting across standards, engineers must reconcile lithium content, copper/magnesium balances and specified heat-treatment cycles to ensure mechanical and corrosion behavior match design intent.

Corrosion Resistance

In atmospheric environments 8017 generally exhibits good resistance provided copper levels are controlled and appropriate tempers are chosen; the naturally aged or annealed conditions often provide better sacrificial behavior than overaged or highly coppered tempers. Localized corrosion such as pitting can occur in chloride-rich environments, and surface finish and cladding or conversion coatings are commonly used to enhance long-term performance.

Marine behavior is acceptable for many components but must be assessed against exposure severity; seawater immersion and splash zones accelerate localized attack and crevice corrosion, especially where galvanic couples with more noble materials exist. Proper surface treatments (anodizing, conversion coatings) and cathodic protection strategies are typical to extend life in marine applications.

Stress corrosion cracking susceptibility increases with tensile stresses and with higher copper or zinc contents; 8017 in peak-aged, high-strength tempers can be more susceptible to SCC than lower-strength, work-hardened alloys. Galvanic interactions are significant when paired with carbon-fiber composites or stainless steel fasteners, and insulating barriers or careful fastener selection are recommended to avoid accelerated corrosion.

Compared with other alloy families, 8017 often provides better specific stiffness and similar or slightly reduced corrosion resistance compared with 5xxx magnesium alloys, and generally superior to high-strength 7xxx alloys which can be more prone to SCC; the final assessment depends heavily on temper, surface finish and local environment.

Fabrication Properties

Weldability

Weldability of 8017 is moderate; fusion welding (TIG/MIG) can be accomplished but requires controlled preheat, low heat-input techniques and the right filler to avoid hot cracking and degraded mechanical properties in the HAZ. Recommended filler alloys are typically Al–Mg–Si or Al–Cu–Li compatible wires specified by the alloy supplier to match corrosion and strength requirements, and post-weld aging can be used to recover strength where geometry permits.

Machinability

Machinability of 8017 is fair in the annealed condition and more challenging in peak-aged tempers due to increased hardness and work-hardening tendencies; tool material selection favors carbide inserts with positive rake and high wear resistance. Cutting speeds and feeds should be established empirically for specific product forms, with good coolant and chip evacuation practices to prevent built-up edge and to maintain surface integrity.

Formability

Formability is best in O or T4-type tempers where ductility is high and strain hardening is moderate; minimum bend radii are thickness-dependent but typically larger than soft 1xxx or 3xxx alloys when in high-strength tempers. Cold forming followed by final aging is a common manufacturing route to achieve complex shapes without losing final mechanical performance, and springback behavior must be considered in tooling design due to higher yield strengths in aged tempers.

Heat Treatment Behavior

As a heat-treatable Al-Li alloy, 8017 responds sensitively to solution treatment, quenching and artificial aging sequences; the common sequence is solutionizing at temperatures near 520–540 °C followed by rapid quench to retain lithium and copper in solid solution. Artificial aging at temperatures in the range of 140–190 °C produces the δ' (Al3Li) and other strengthening phases, and peak-aged conditions (T6) are achieved by controlling time and temperature to produce a fine, high-density precipitate distribution.

Overaging or incorrect aging temperatures can lead to coarsening of precipitates and reduced strength, along with possible reductions in ductility and corrosion resistance; therefore, precise thermal cycles are used in aerospace-grade processing. For some components a T8 route (solution treat, quench, stretch/cold work and artificially age) is used to combine precipitation and work-hardening, optimizing both yield strength and fatigue performance.

Non-heat-treatable strengthening in related product lines is achieved via work hardening (H-series tempers) and annealing is used to restore ductility; however, such routes are less effective at exploiting the full potential of the lithium precipitation system than controlled T6/T651 processes.

High-Temperature Performance

Strength retention in 8017 degrades progressively with temperature; significant loss of yield and tensile strength begins above approximately 120–150 °C as precipitates begin to dissolve or coarsen. Continuous operation at elevated temperatures is therefore limited, and designers typically specify service temperature limits below 120 °C to avoid permanent softening.

Oxidation in air is modest and similar to other aluminum alloys owing to the protective alumina layer, but the alloy should not be used in oxidative high-temperature environments without protective coatings. HAZ and thermally cycled regions near welds can experience localized softening and must be considered when designing high-temperature components.

Applications

Industry	Example Component	Why 8017 Is Used
Aerospace	Fuselage or wing secondary structure	High specific strength and stiffness reduce weight while maintaining structural performance
Automotive / Transportation	High-performance chassis components	Weight reduction for fuel economy and dynamic stiffness improvement
Marine	Structural frames and fittings	Favorable strength-to-weight and reasonable corrosion resistance with protective finishes
Electronics	Structural heat spreaders and brackets	Lower density combined with acceptable thermal conductivity and mechanical strength

8017 is frequently selected for applications where reducing mass without compromising stiffness or fatigue resistance is critical, and where manufacturing routes can accommodate its heat-treatment and welding requirements. The alloy's performance envelope is most attractive when an integrated design–manufacturing approach is used to take advantage of post-forming aging and surface protection.

Selection Insights

Choose 8017 when specific strength and stiffness per unit mass are driving metrics and when manufacturing can support solution heat treatment, quenching and controlled aging. It is a good choice for components where a weight penalty would significantly impact system performance, and where post-forming heat treatment is feasible.

Compared with commercially pure aluminum (e.g., 1100), 8017 trades higher strength and stiffness and lower density for reduced electrical/thermal conductivity and more constrained formability; 1100 remains preferable where maximum formability and conductivity are required. Versus common work-hardened alloys such as 3003 or 5052, 8017 occupies a higher-strength niche with comparable or slightly