Aluminum 2017: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

Alloy 2017 is a member of the 2xxx series of aluminum alloys, which are copper-containing, heat-treatable alloys optimized for elevated strength and stiffness. Its chemical system is dominated by copper as the principal alloying addition, with modest contributions from manganese, magnesium, and trace elements that refine microstructure and influence processing response.

Strengthening in 2017 is primarily achieved through precipitation hardening (solution treatment, quench and artificial aging) combined with work-hardening in some tempers; this alloy reaches much higher yield and tensile strengths than most non-heat-treatable commercial alloys. Key traits of 2017 include high strength, reasonable machinability, moderate corrosion resistance compared to other Al alloys, and limited formability in peak-aged conditions; weldability is more challenging than in 5xxx and 6xxx families and requires care to avoid HAZ softening and hot cracking.

Typical industries using 2017 include aerospace (fittings, forgings, and structural components), defense, transportation, precision machined parts, and certain high-strength consumer components where a balance of machinability and elevated strength is needed. Engineers select 2017 when a high strength-to-weight ratio and good machinability are required and when the design can accommodate intensive corrosion protection or when localized strengthening via heat treatment is advantageous.

Compared with other aluminum families, 2017 is chosen over softer, more formable alloys when strength and fatigue resistance are priorities, and it is selected over higher-strength but lower-ductility alloys when machinability and predictable aging behavior are important design considerations.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Fully annealed; maximum ductility for forming
T4	Medium-High	Moderate	Fair	Poor-Moderate	Solution heat treated and naturally aged; balanced for machining
T6	High	Low-Moderate	Limited	Poor	Solution heat treated and artificially aged for peak strength
T651	High	Low-Moderate	Limited	Poor	T6 with stress-relief by stretching; used for stability in machining
H14	Medium	Low-Moderate	Limited	Poor-Moderate	Strain-hardened to half-hard; used where modest strength increase is needed
H18	Medium-High	Low	Limited	Poor-Moderate	Fully hard by work-hardening; used for specialized sheet applications

Temper strongly controls the trade-off between strength and ductility in 2017. Annealed (O) condition provides the greatest formability and is preferred for deep drawing and extensive cold forming, whereas T6/T651 push strength to the alloy’s practical maximum at the expense of elongation and bendability.

The T4 condition is commonly used as a machinable temper because it offers higher strength than O while avoiding the extreme hardness and reduced toughness of T6; H-series tempers provide incremental work-hardened strength useful for sheet and strip but are generally less uniform than heat-treated tempers.

Chemical Composition

Element	% Range	Notes
Si	≤ 0.12	Kept low to avoid brittle intermetallics; reduces melt fluidity effects
Fe	≤ 0.30	Impurity element; excessive Fe forms hard intermetallic particles that reduce ductility
Cu	3.5 – 4.5	Principal strengthening element; forms Al2Cu precipitates during aging
Mn	0.3 – 0.9	Grain structure refinement and improved toughness; reduces anisotropy
Mg	0.2 – 0.8	Contributes to precipitation hardening synergy with Cu and improves strength
Zn	≤ 0.25	Minor; high Zn can increase susceptibility to stress corrosion cracking
Cr	0.10 – 0.25	Controls recrystallization and grain structure during thermomechanical processing
Ti	≤ 0.15	Grain refiner used during casting and primary processing
Others	≤ 0.05 each, ≤ 0.15 total	Includes trace elements and residuals; balance is aluminum

The high copper content is the defining chemical feature of 2017 and is responsible for its heat-treatable nature and high precipitation-strength potential. Manganese and chromium are deliberately controlled to refine grain structure and to stabilize strength and toughness, while magnesium adjusts age-hardening kinetics and contributes to overall strength.

Mechanical Properties

In tensile behavior, 2017 exhibits high ultimate tensile strength and correspondingly high yield strength in T6 and T651 tempers due to dense populations of Al–Cu precipitates. Elongation is substantially reduced in peak-aged conditions, so ductility-sensitive designs often use T4 or O tempers or incorporate stress-relief/stretching to recover some toughness.

Hardness in 2017 tracks temper: annealed material is relatively soft, while T6 gives high Brinell/Vickers hardness consistent with medium-carbon steel equivalents in certain service contexts. Fatigue performance benefits from the high static strength but can be compromised by surface defects, coarse intermetallics, and corrosion pits; controlled processing and shot peening can significantly extend fatigue life.

Thickness and product form affect mechanical performance through cooling rates and grain size; thinner sections tend to achieve more uniform quench rates and more consistent age response, whereas thick forgings and plates require tailored heat-treatment cycles to avoid retained soft cores.

Property	O/Annealed	Key Temper (T6/T651)	Notes
Tensile Strength (MPa)	~200 – 250	~420 – 490	T6 values are typical for wrought tempers; depends on section thickness and aging cycle
Yield Strength (MPa)	~60 – 120	~330 – 370	Substantial increase with heat treatment; yield can be lower in thick sections due to soft cores
Elongation (%)	~18 – 25	~6 – 12	Annealed shows high ductility; T6 elongation reduced but acceptable for many machined parts
Hardness (HB)	~30 – 60	~110 – 140	Hardness ranges depend on processing and specific aging treatments

Physical Properties

Property	Value	Notes
Density	~2.78 g/cm³	Typical for high-strength Al-Cu alloys; slightly higher than pure Al due to alloying
Melting Range	~500 – 650 °C	Onset depressed by copper and other alloying elements; not a sharp melting point
Thermal Conductivity	~120 – 150 W/m·K	Lower than pure aluminum but sufficient for many thermal-management applications
Electrical Conductivity	~28 – 35 % IACS	Reduced relative to pure Al due to Cu and other solutes
Specific Heat	~0.90 kJ/kg·K (≈900 J/kg·K)	Typical for aluminum alloys at room temperature
Thermal Expansion	~23 – 24 µm/m·K	Coefficient of thermal expansion comparable to other Al alloys; useful for composite design

Thermal and electrical conductivities are reduced relative to pure aluminum because solute atoms and precipitates scatter electrons and phonons; however, 2017 retains enough conductivity for some conductive structural applications. The melting range and thermal expansion behavior must be considered during welding and heat treatment since differential expansion and retained phases can influence distortion and residual stresses.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.3 – 6 mm	Good uniformity in thin gauges	O, H14, T4, T6	Widely used for formed and machined components; short-transverse properties important
Plate	6 – 150 mm	Thickness gradients affect quench and aging	T4, T6, T651	Thick sections require long solution times and tailored quench to avoid soft cores
Extrusion	Cross-sections variable	Mechanical anisotropy depends on extrusion ratio	T4, T6	Limited compared to 6xxx alloys but used for high-strength profiles
Tube	OD 6 mm – 300 mm	Strength similar to sheet for thin-wall tubes	T4, T6	Common for structural and hydraulic components where machinability is needed
Bar/Rod	3 – 200 mm dia.	Excellent machinability in T4; peak strength in T6	T4, T6, O	Used for fasteners, fittings, and precision turned components

Form and size strongly influence final properties; thin products quench faster and typically reach target strength more reliably, while thick plates and extrusions require careful control of heat-treatment parameters. Selection of product form must account for downstream operations such as machining, joining, and surface finishing to avoid HAZ softening and to maintain dimensional tolerances.

Equivalent Grades

Standard	Grade	Region	Notes
AA	2017 / 2017A	USA	Common commercial designations; 2017A is a tighter-control variant
EN AW	2017A	Europe	EN specification aligns chemistry and mechanicals with AA 2017A
JIS	A2017	Japan	Japanese designation consistent with wrought Al–Cu series practices
GB/T	2A12 (approx.)	China	Often used as a rough Chinese equivalent; consult mill certificates for exact match

Standards across regions aim to produce functionally equivalent material but differ in permitted tolerances for trace elements, mechanical property limits, and naming conventions; for critical applications always compare specific material certificates and, when necessary, perform qualification testing. The A suffix (2017A) typically denotes tighter chemistry control that improves consistency in heat treatment response and fatigue performance.

Corrosion Resistance

Atmospheric corrosion resistance of 2017 is moderate and inferior to 5xxx (Mg-bearing) and 6xxx (Mg+Si) series alloys; the copper-rich matrix increases susceptibility to localized corrosion and reduces performance in aggressive environments unless protected. In industrial atmospheres and rural environments, properly coated or anodized 2017 components can deliver satisfactory life, but localized pitting and filiform corrosion must be considered in finish and sealing design.

In marine environments, 2017 performs less well than Al-Mg alloys; chloride-induced pitting and crevice corrosion can be significant without cathodic protection, coatings, or sacrificial anodes. Stress corrosion cracking (SCC) is a known risk for high-copper alloys under tensile stress in warm saline environments; designs requiring SCC resistance should favor other alloy families or implement strict corrosion mitigation.

Galvanic interactions should be carefully managed: 2017 is anodic to many steels but cathodic relative to more noble aluminum alloys with heavy anodic coatings; when mating with carbon steel, isolation and protective measures are needed. Compared to 1xxx or 3xxx series alloys, 2017 sacrifices corrosion robustness for higher strength and must be selected with surface treatment and environment in mind.

Fabrication Properties

Weldability
Welding 2017 is challenging relative to 5xxx and 6xxx alloys because of copper content and hot-cracking tendency in fusion welding processes. TIG and MIG welding are possible with tailored parameters and appropriate filler metals (commonly 4043 or 5356 for reduced cracking risk), but the weld heat-affected zone (HAZ) will typically be softer than the peak-aged base metal and may require post-weld heat treatment or mechanical reinforcement.

Machinability
2017 is considered one of the better machinable high-strength aluminum alloys, especially in T4 and O tempers; it machines with good surface finish and predictable tool life when using carbide tooling and high feed rates. Recommended tooling uses positive rake geometry with rigid setups, coolant or air blast for chip evacuation, and moderate speeds to avoid work-hardening at the surface; chip morphology is normally continuous but can form stringers when Mn-rich intermetallics are present.

Formability
Cold forming is easiest in O or T4 tempers where elongation and bendability are highest; minimum bend radii depend on temper and thickness but are generally larger than for softer alloys like 1100. For deep drawing or complex forming, annealing prior to forming is common, and designers must account for springback which is greater in high-strength tempers such as T6; warm-forming techniques can sometimes extend formability without sacrificing final strength.

Heat Treatment Behavior

As a heat-treatable Al–Cu alloy, 2017 responds to classical precipitation sequences: solution treatment dissolves Cu-rich phases into a supersaturated solid solution, rapid quenching retains that condition, and controlled artificial aging precipitates strengthening Al2Cu and associated phases. Typical solution treatments occur at temperatures around 495–535 °C depending on section size and fabrication, with immediate quench to room temperature to suppress coarse intermetallic formation.

Artificial aging to reach the T6 condition is typically performed at temperatures in the range of 160–190 °C for times on the order of several hours; T4 is achieved by natural aging after quench but is slower and may lead to lower peak strength compared to artificial aging. Thickness, prior cold work, and minor alloying variations shift the optimal T-T-T (time-temperature-transformation) window; overaging reduces strength but improves ductility and corrosion resistance in some cases.

Non-heat-treatable work-hardening (H tempers) provides a route to intermediate strength levels without full solution and aging cycles; annealing (O) restores ductility and is used prior to forming operations. Post-weld or patch repairs often require local solution/aging sequences or acceptance of HAZ softening in the design.

High-Temperature Performance

Service temperatures for 2017 are generally limited to well below typical aging temperatures; elevated temperature exposure leads to coarsening of precipitates and progressive strength loss. Long-term exposure above ~150 °C will reduce the peak-aged properties and can stabilize into overaged conditions with lower yield and tensile strength; design must account for this when components experience elevated ambient or process temperatures.

Oxidation is not a primary failure mode for 2017 in normal atmospheric service because of the protective aluminum oxide film, but at high temperatures scaling and accelerated diffusion of alloying elements can alter surface and near-surface properties. In welded assemblies, HAZ softening and loss of strength under thermal load can be the controlling limitation rather than bulk oxidation, necessitating thermal management or selection of alternate alloys for persistent high-temperature exposure.

Applications

Industry	Example Component	Why 2017 Is Used
Aerospace	Fittings, brackets, forgings	High strength-to-weight and good fatigue/machinability balance
Defense	Structural mounts, housings	Machinable, high-strength alloy suitable for precision parts
Automotive	High-strength machined components	Offers machining productivity and weight savings for small parts
Electronics	Structural frames, connectors	Adequate thermal conductivity and stiffness for chassis applications
Commercial	Fasteners, rivets, couplings	Strength and dimensional stability after heat treatment

2017 finds its niche where machined parts require high static and fatigue strengths combined with good machinability and dimensional stability after heat treatment. It is particularly valuable for small to medium-sized structural parts where high-strength alternatives are either too brittle or too costly to machine efficiently.

Selection Insights

Choose 2017 when the design requires higher strength and better machinability than commercially pure aluminum and when subsequent surface protection or anodizing can mitigate the alloy’s moderate corrosion susceptibility. It is advantageous for precision machined fittings, aerospace brackets, and structural components where heat treatment can be leveraged to tune performance.

Compared with commercially pure aluminum (1100), 2017 trades off electrical and thermal conductivity plus forming ease for substantially higher strength and improved fatigue resistance; use 1100 when conductivity and maximum formability are primary. Compared with work-hardened alloys such as 3003 or 5052, 2017 provides higher strength and better machinability at the cost of reduced corrosion resistance and more complex joining requirements.

When compared with common heat-treatable alloys like 6061 or 6063, 2017 can be preferred for applications that prioritize maximum machinability and a specific precipitation-strengthening response rather than the broader corrosion resistance and weldability of 6xxx alloys; choose 2017 where Cu-based precipitation and the resulting mechanical properties are essential and where surface protection can be guaranteed.

Closing Summary

Alloy 2017 remains relevant due to its combination of high precipitation-strength, predictable aging response, and excellent machinability for high-performance structural and precision components. When used with appropriate corrosion protection and carefully controlled heat treatment, 2017 offers designers a cost-effective route to elevated strength-to-weight performance in aerospace, defense, and high-strength commercial applications.