Aluminum A5086: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

A5086 is an aluminum-magnesium alloy in the 5xxx series, characterized by magnesium as the principal alloying element and aluminum as the balance. It belongs to the non-heat-treatable group where strength is developed primarily through strain hardening and controlled cold work rather than precipitation hardening. The alloy exhibits a favorable combination of moderate-to-high strength, very good corrosion resistance in marine and atmospheric environments, and excellent weldability, while retaining reasonable formability in softer tempers. Typical industries using A5086 include shipbuilding, marine structures, cryogenic tanks, pressure vessels, and transportation components where corrosion resistance and toughness are required over peak heat-treatable strength.

A5086 is often chosen when a durable, weldable aluminum with superior seawater corrosion resistance is required, and when the design relies on cold-working to tune strength. Compared with heat-treatable alloys, it trades off some maximum achievable strength for better performance in corrosive and welded assemblies. The alloy is favored where structural reliability and resistance to localized corrosion dictate material selection, and where fabrication processes include large welded joints and significant forming operations. Its balance of toughness, damage tolerance, and service-life in aggressive environments keeps it relevant for both legacy and modern engineering applications.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Fully annealed condition for maximum ductility
H111	Low–Moderate	High	Very good	Excellent	Slightly strain-hardened; general-purpose forming
H116	Moderate	Moderate	Good	Very good	Marine-grade temper with improved corrosion resistance
H32	Moderate–High	Moderate	Fair	Very good	Strain-hardened and partially annealed for higher strength
H34	High	Lower	Limited	Very good	Heavier strain-hardening for structural parts
H36	Highest (work-hardened)	Lower	Poor–Limited	Very good	Maximum commercially available strain-hardening

Temper strongly controls the balance between strength and ductility in A5086 by varying the amount of permanent cold work and any stabilizing thermal steps. Softer tempers such as O and H111 are used where forming is extensive and stretch operations are required, while H32–H36 series are selected where higher yield and tensile properties are needed without heat treatment.

Chemical Composition

Element	% Range	Notes
Si	≤ 0.40	Impurity control; excessive Si can form intermetallics that reduce ductility
Fe	≤ 0.40	Iron is an impurity; limits are kept low to avoid coarse intermetallics
Mn	0.20–0.70	Improves strength and control of grain structure; contributes to work-hardening response
Mg	3.5–4.5	Principal strengthening element; controls corrosion behavior and solid-solution strengthening
Cu	≤ 0.10	Low copper to preserve corrosion resistance; higher Cu increases susceptibility to localized attack
Zn	≤ 0.25	Minor; kept low to avoid susceptibility to stress-corrosion in some environments
Cr	0.05–0.25	Small additions refine grain structure and improve resistance to stress-corrosion cracking
Ti	≤ 0.15	Grain refiner when intentionally added; otherwise limited as an impurity
Others (each)	≤ 0.05	Total others kept minimal; aluminum is balance (~ remainder)

Magnesium dominates mechanical and corrosion behavior by providing solid-solution strengthening and by influencing the electrochemical potential of the matrix. Chromium and manganese are present to control grain structure and to mitigate certain corrosion modes and recrystallization during fabrication. Strict control of iron, silicon, copper, and zinc is necessary to maintain ductility, toughness, and corrosion resistance in marine environments.

Mechanical Properties

A5086 displays a combination of ductility and strength that strongly depends on temper and cold work level; annealed (O) material offers high elongation but the lowest yield and tensile strengths, while H32–H36 tempers provide progressively higher yield with reduced elongation. Tensile behavior is typically characterized by a moderately high work-hardening exponent in the early plastic range, giving good energy absorption and damage tolerance under overload. Fatigue resistance is generally good for an aluminum alloy, but fatigue life is sensitive to surface finish, weld quality, and stress concentrators—welded joints reduce fatigue endurance significantly compared with parent metal.

Hardness scales with strain hardening and correlates to tensile/yield increases; expect a significant jump in Vickers or Brinell hardness moving from O to H34/H36. Thickness affects both strength and ductility through constraint during cold working; thicker sections are harder to strain-harden uniformly and may show lower effective elongations. Thermal exposure around welding or localized heating can soften the H-tempered zones in the heat-affected zone (HAZ), reducing yield locally and necessitating design allowances for reduced HAZ strength.

Property	O/Annealed	Key Temper (H32/H116)	Notes
Tensile Strength	Typical 120–200 MPa	Typical 260–340 MPa	Ultimate strength rises with strain hardening; wide range depends on temper and thickness
Yield Strength	Typical 35–80 MPa	Typical 170–270 MPa	Yield increases strongly with H-temper; H116 is balanced marine temper
Elongation	Typical 25–35%	Typical 8–20%	Annealed offers highest elongation; heavily cold-worked tempers exhibit lower ductility
Hardness	Low (HV ~25–40)	Moderate–High (HV ~60–90)	Hardness follows strength and cold working; values depend on measurement scale and temper

Physical Properties

Property	Value	Notes
Density	~2.66 g/cm³	Typical for aluminum-magnesium alloys; gives good strength-to-weight ratio
Melting Range	~590–650 °C	Solidus/liquidus depend on exact composition; alloy melts below pure Al's liquidus due to Mg
Thermal Conductivity	~130–140 W/m·K (at 25 °C)	High conductivity makes it useful for heat-dissipation and cooling components
Electrical Conductivity	~30–35 % IACS	Lower than pure Al due to alloying but acceptable for many electrical/thermal applications
Specific Heat	~0.90 kJ/kg·K	Useful for thermal management calculations and transient heating analysis
Thermal Expansion	~23–25 µm/m·K (20–100 °C)	Coefficient similar to other aluminum alloys; important for joined assemblies with dissimilar metals

The physical constants show that A5086 preserves many of aluminum's favorable properties, such as low density and high thermal conductivity, while alloying reduces electrical conductivity and raises strength. Thermal expansion and conductivity data are central to design in assemblies with dissimilar materials or where thermal cycling occurs, because differential expansion can induce stresses or fatigue. The melting and solidification range are relevant to welding and casting-related processes, with care required to avoid excessive grain coarsening and to control HAZ properties.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.5–6.0 mm	Uniform mechanical properties; easier to cold work	O, H111, H116	Widely used in panels, hull plating, and formed assemblies
Plate	6–150+ mm	Lower accessible cold work; properties vary with rolling schedule	H32, H34, H36	Thick sections used for structural components; heavy rolling controls grain orientation
Extrusion	Profiles up to several meters	Strength depends on post-extrusion work	H111, H32	Extrusions allow complex cross-sections; heat from extrusion can affect temper
Tube	Diameters small to large; wall thickness variable	Mechanical performance influenced by forming and aging	H111, H32	Seamless and welded tubes used in structural and pressure applications
Bar/Rod	Diameters up to 200 mm	Typically strain-hardened or annealed	O, H111, H32	Used for machined components and fittings where toughness is needed

Manufacturing form influences both achievable mechanical properties and processing choices. Sheet and thin-gauge applications permit significant cold forming and strain hardening to meet strength targets while retaining formability. Plate and thick sections present challenges for uniform strain hardening and may require heavier tempers or alternative joining strategies to manage HAZ softening. Extrusions and tubes are shaped hot and often gauge-sensitive; subsequent cold work or straightening operations are used to establish target tempers.

Equivalent Grades

Standard	Grade	Region	Notes
AA	A5086	USA	Aluminum Association designation for the alloy chemistry and commercial product forms
EN AW	5086	Europe	EN AW-5086 commonly used in European specifications with similar composition limits
JIS	A5086	Japan	Japanese industry typically maps to AA/EN equivalents for procurement and standards
GB/T	5086	China	Chinese GB/T designations align closely to AA/EN chemistries and typical tempers

Regional standards generally describe the same base chemistry but may differ in allowed tolerances, specified tempers, or testing requirements for mechanical properties. Procurement and specification calls should reference the appropriate local standard to capture mandated tolerances, testing protocols, and supply-chain acceptance criteria. Minor differences in maximum impurity limits or temper designations can have practical impacts on weldability, corrosion performance, and certification acceptance across different markets.

Corrosion Resistance

A5086 exhibits excellent atmospheric corrosion resistance and is particularly well-suited to marine and offshore service due to its high magnesium content and carefully controlled impurities. In seawater and splash zones it forms a stable oxide and hydroxide film that limits deep pitting, and certain tempers (H116) are tailored for enhanced resistance to intergranular and localized corrosion. Stress-corrosion cracking susceptibility increases with tensile stress and certain microstructural conditions; controlled tempers and proper design to avoid high tensile residuals are important to minimize SCC risk.

Galvanic interactions must be considered when joining A5086 to more noble metals such as stainless steel or copper; aluminum will be the anodic member and will corrode preferentially unless electrically insulated or cathodic protection is provided. Compared with 2xxx and 7xxx series alloys, A5086 offers markedly superior corrosion resistance in chloride-containing environments, though it does not reach the corrosion resistance of some high-purity commercial aluminum grades in specific atmospheres. Design for corrosion resistance should consider alloy temper, surface finish, and maintenance regimes to achieve long service life in aggressive environments.

Fabrication Properties

Weldability

A5086 has excellent weldability with common fusion methods including MIG/GMAW and TIG/GTAW, and it responds well to solid-state processes such as friction stir welding. Recommended filler alloys for welds are typically 5356 or 5183, chosen to balance strength and corrosion resistance while avoiding hot-cracking; 5356 is common for marine applications because of its good strength and ductility. Welds are susceptible to HAZ softening where strain-hardened parent metal loses strength locally, requiring design margin or post-weld cold work when necessary.

Machinability

Machinability of A5086 is moderate and generally lower than free-machining aluminum alloys due to higher strength and work-hardening; machinability indices are typically in the 40–60% range relative to pure aluminum benchmarks. Carbide tooling and rigid setups with appropriate chip breakers are recommended to handle continuous, ductile chips and to maintain surface finish. Lower cutting speeds with heavier feed and positive rake tools can improve tool life and reduce built-up edge for common turning and milling operations.

Formability

Formability is excellent in annealed and lightly tempered conditions, enabling deep drawing, bending, and complex stretch forming operations used in hull plating and bodywork. Minimum bend radii depend on temper and thickness, but O and H111 can achieve tight radii due to high elongation; heavy H32–H36 tempers require larger radii and may be limited to simple bends. Cold working raises strength effectively, and designers exploit this to achieve local strengthening after forming; however, overworking or severe bending can produce springback and surface cracking if not controlled.

Heat Treatment Behavior

A5086 is a non-heat-treatable alloy and does not gain strength from precipitation hardening; thermal treatments mainly serve to anneal, stabilize, or recrystallize the microstructure. Annealing (full softening to O condition) is performed by heating into the range where recrystallization occurs followed by controlled cooling, restoring ductility for subsequent forming operations. Artificial aging and T-temper transitions are not relevant for strength increases in this alloy, though thermal exposure during welding can locally anneal and reduce strength in H-tempers.

Work hardening is the primary means of increasing strength in A5086; controlled cold rolling, stretching, or bending steps are used to achieve H11x–H36 tempers. Stabilization treatments (mild thermal exposure) can be applied to arrest natural aging-like processes or to relieve residual stresses, but they will not produce the hardening effects seen in 6xxx or 7xxx series alloys. Design and process engineers should plan forming and welding sequences to manage the balance between desired strength and retained ductility, accounting for HAZ softening and possible rework.

High-Temperature Performance

A5086 retains useful mechanical properties at moderately elevated temperatures, but strength and stiffness degrade as temperature rises; structural properties fall off progressively above ~100–150 °C. For sustained service above this range, designers should consider derating factors and potential creep or relaxation phenomena depending on load and exposure duration. Oxidation is minimal for aluminum alloys at common service temperatures, but protective films can be disrupted in aggressive thermal-cycling or high-humidity conditions, altering local corrosion behavior.

Welded regions are particularly sensitive to elevated temperatures because prior HAZ softening combined with thermal exposure can further reduce local yield and fatigue strength. Long-term exposure near the melting range is of course unsuitable and will cause serious microstructural degradation; for high-temperature applications, alternative alloys specifically designed for elevated-temperature stability are preferred. For intermittent temperatures and short excursions, A5086 can perform acceptably provided that design stresses and joint details are conservative.

Applications

Industry	Example Component	Why A5086 Is Used
Marine	Hull plating, superstructure, fittings	Excellent seawater corrosion resistance and weldability
Transportation	Trailer bodies, railcars	High strength-to-weight, toughness, and damage tolerance
Aerospace	Secondary structure, interior fittings	Good strength and corrosion resistance for non-primary structural parts
Energy / Pressure Vessels	Cryogenic tanks, heat exchangers	Good toughness at low temperature and thermal conductivity
Electronics / Thermal	Heat spreaders, housings	High thermal conductivity and low density for thermal management

A5086’s combination of corrosion resistance, weldability, and formability makes it a go-to choice for structural applications exposed to marine or outdoor environments. The alloy’s ability to maintain toughness at low temperatures also expands its use into cryogenic and refrigerated applications. Where engineered joining and long-term durability are prioritized over absolute peak tensile values, A5086 provides a pragmatic balance of properties and manufacturability.

Selection Insights

Choose A5086 when the application requires a weldable, corrosion-resistant aluminum with good strength provided by cold work and when service will include exposure to seawater or aggressive atmospheres. Compared with commercially pure aluminum (1100), A5086 trades some electrical conductivity and ease of forming for substantially higher strength and better resistance to mechanical loading. Compared with 3xxx (e.g., 3003) or 5xxx alloys like 5052, A5086 typically offers higher strength while retaining comparable or improved corrosion resistance in marine conditions.

Against heat-treatable alloys such as 6061 or 6063, A5086 will not reach the same peak, precipitation-hardened strengths, but it is often preferred where welded assemblies and long-term chloride exposure are dominant design drivers. Consider cost, availability of specific tempers, and fabrication sequence: if extensive welding and exposure to seawater are expected, A5086 (H116/H32) is frequently the optimal trade-off between strength, longevity, and manufacturability.

Closing Summary

A5086 remains a key engineering aluminum alloy where corrosion resistance, weldability, and damage-tolerant strength are required without reliance on heat treatment. Its alloy chemistry and tempering options allow engineers to tailor properties through cold work and processing, making it a durable, versatile choice for marine, transportation, and cryogenic structural applications.