Aluminum 5082: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

5082 is a member of the 5xxx series of wrought aluminum alloys, characterized primarily by magnesium as the principal alloying element. It is a non-heat-treatable, strain-hardenable alloy that achieves elevated strength through cold work rather than precipitation hardening.

Major alloying species in 5082 are magnesium (typically in the ~4.0–5.0 wt% range), with smaller additions of manganese and trace chromium to control grain structure and enhance corrosion resistance. These additions give 5082 a balance of moderate-to-high strength, good ductility in annealed condition, excellent seawater corrosion resistance, and generally good weldability.

Key traits that define 5082 are its elevated strength among non-heat-treatable Al-Mg alloys, strong resistance to marine and atmospheric corrosion, favorable fatigue properties in many conditions, and fair formability in annealed tempers. Typical industries using 5082 include marine construction, transportation (fuel tanks, trailers), pressure vessel and cryogenic tankage, and electronic enclosures where corrosion resistance and moderate strength are valued.

Engineers select 5082 when a design requires higher strength than common commercial-purity aluminum without sacrificing corrosion performance or weldability. It is chosen over heat-treatable alloys when weld distortion and post-weld temper recovery are concerns, and over lower-strength 1xxx/3xxx series alloys when structural integrity or fatigue life is a priority.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High (20–30%+)	Excellent	Excellent	Fully annealed; best formability and ductility
H111	Low-Medium	Moderate	Good	Excellent	Slightly strain-hardened; commonly supplied for bending
H112	Medium	Moderate	Good	Excellent	Control of mechanical properties via processing
H32	Medium-High	Reduced (8–15%)	Fair	Very Good	Strain-hardened and stabilized; common marine temper
H34	Medium-High	Reduced	Fair	Very Good	More severe strain hardening than H32; higher strength
H116 / H321	Medium-High	Moderate	Good	Very Good	Designed for improved stress-corrosion cracking resistance and weldability

Temper has a strong influence on the balance between strength and formability for 5082. Annealed O temper maximizes ductility and drawing operations, while H32/H34 deliver higher yield and tensile strengths at the expense of bendability and elongation.

Weldability remains good across most tempers since 5082 is non-heat-treatable, but deformation temper and strain aging after welding can change local mechanical properties; designers often select a temper that balances forming needs with final-strength requirements.

Chemical Composition

Element	% Range	Notes
Si	≤ 0.40	Impurity that can reduce ductility if elevated
Fe	≤ 0.50	Typical impurity; affects grain boundary phases
Mn	0.15–0.40	Improves strength and corrosion resistance via dispersoids
Mg	4.0–5.0	Principal strengthening element; enhances corrosion resistance
Cu	≤ 0.10	Limited to avoid corrosion and embrittlement
Zn	≤ 0.25	Low; excessive Zn can reduce corrosion resistance
Cr	≤ 0.25	Controls grain structure and helps combat sensitization
Ti	≤ 0.15	Grain refiner in cast and wrought processing
Others (each)	≤ 0.05	Other trace elements; Al balance

Magnesium is the primary strengthener and also enhances resistance to seawater corrosion by promoting a protective surface film. Manganese and chromium are added in small amounts to stabilize microstructure and limit grain growth, which improves toughness and reduces susceptibility to localized corrosion.

Impurities such as iron and silicon are controlled because they form intermetallic particles that can be sites for pitting or crack initiation under fatigue and corrosive environments. The overall composition is tuned to maximize the combination of strength, weldability, and marine corrosion performance.

Mechanical Properties

In tensile loading 5082 exhibits a classic strain-hardened response: annealed O temper shows relatively low yield and tensile strengths with high elongation, while H-tmpers raise both yield and ultimate strengths at the cost of ductility. Yield behavior is typically progressive with cold work; work hardening exponents vary with temper and thickness, influencing forming and springback behavior.

Hardness correlates with temper: annealed material has low Brinell or Vickers hardness values, and strain-hardened tempers show significantly higher hardness that tracks with measured yield strength. Fatigue strength for 5082 in marine environments is often favorable compared with many 6xxx alloys, provided design avoids stress concentrators and accounts for the alloy's notch sensitivity in corrosion-prone conditions.

Material thickness and fabrication history strongly influence mechanical properties; thinner gauge material often attains slightly higher yield due to processing strain, and thick plate may be supplied in less-worked tempers requiring post-forming strain-hardening to achieve design strengths.

Property	O/Annealed	Key Temper (H32 / H116)	Notes
Tensile Strength	110–145 MPa	210–260 MPa	Values depend on thickness and exact temper; typical ranges
Yield Strength	40–70 MPa	120–165 MPa	Yield increases strongly with strain hardening
Elongation	20–35%	8–15%	Ductility reduced in cold-worked tempers
Hardness (HB)	25–40	55–85	Correlates with yield; measured values depend on temper and thickness

Physical Properties

Property	Value	Notes
Density	2.66 g/cm³	Typical for Al-Mg alloys; excellent strength-to-weight
Melting Range	~590–645 °C	Alloy solidus/liquidus spread; care needed in welding and brazing
Thermal Conductivity	~120 W/m·K (at 25 °C)	Slightly reduced versus pure Al due to alloying
Electrical Conductivity	~28–36 %IACS	Lower than 1xxx series due to Mg content
Specific Heat	~0.90 J/g·K	~900 J/kg·K; useful for thermal management estimates
Thermal Expansion	~23–24 µm/m·K	Typical aluminum thermal expansion; important for joint design

5082 retains excellent thermal conductivity compared with many steels and some aluminum alloy families, which makes it useful for heat-dissipating structures where corrosion resistance is required. The relatively high coefficient of thermal expansion requires attention in dissimilar-material joints and precision assemblies, especially in cycling thermal environments.

Density and thermal properties combine to make 5082 attractive where weight savings plus thermal performance are required, though electrical conductivity is reduced relative to purer aluminum grades and therefore less suited where high conductivity is the primary requirement.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.3–6.0 mm	Wide range via temper	O, H111, H32	Widely used in marine panels, fuel tanks
Plate	6–100+ mm	Lower cold work in thick plate; heavier sections	O, H112	Thick sections often require fabrication after shaping
Extrusion	Various cross-sections	Strength varies with section and temper	H32, H111	Widely used for structural profiles and stiffeners
Tube	0.5–10+ mm wall	Strength depends on cold work and drawing	O, H32	Common for pressure and conduit applications
Bar/Rod	Ø6–50+ mm	Machinability and forming differ by temper	O, H111	Used for fittings, fasteners, specialty machined parts

Sheet and plate production routes and subsequent cold work create the most common practical differences in strength and formability for 5082. Thin-gauge sheet is often supplied in softer tempers for deep drawing and bending, while plate and extrusions are selected when stiffness and section properties are prioritized.

Extruded profiles allow designers to combine thin web sections with stiffening ribs; they can be age-stable in the H32 family and are frequently chosen for marine superstructure and transport frame elements where weldability and corrosion resistance are key.

Equivalent Grades

Standard	Grade	Region	Notes
AA	5082	USA	Standard wrought designation under Aluminum Association
EN AW	5082	Europe	Often specified as EN AW-5082; similar composition controls
JIS	A5082	Japan	Japanese industrial standard equivalent; compositionally similar
GB/T	5082	China	Chinese standard mirrors typical Al-Mg-Mn chemistry

Equivalent designations across regions are broadly interchangeable for general engineering applications, but mill certifications and specified property tables should be checked for exact compositional limits and temper designations. Slight regional differences may exist in maximum impurity limits (Fe, Si) or in naming of stabilization tempers (H116 vs H321), which can influence specified corrosion performance in critical marine or cryogenic service.

When substituting material sources, engineers should verify mechanical property certificates and any supplementary requirements such as stress-relieving, surface finish, and trace element limits to ensure performance parity.

Corrosion Resistance

5082 exhibits excellent resistance to general atmospheric and seawater corrosion due to the protective oxide film stabilized by magnesium and manganese. It performs particularly well in marine environments compared with many heat-treatable alloys, showing limited pitting and good resistance to uniform corrosion when proper surface treatments and design practices are used.

The alloy is relatively resistant to stress-corrosion cracking compared with certain high-strength aluminum systems, but sensitization and intergranular corrosion can occur if exposed to elevated temperatures for prolonged periods, particularly in the range where magnesium-rich precipitates can form. Designers should avoid long-term exposures above ~65–100 °C without testing and should consider cathodic protection or coatings for aggressive service.

Galvanic interactions with dissimilar metals must be managed; 5082 is anodic relative to stainless steels and tin-bronze, and cathodic relative to pure zinc. Appropriate isolation, sacrificial protection, and fastener material selection are essential to prevent accelerated corrosion at joints. Compared with 6xxx series alloys, 5082 typically provides superior marine corrosion resistance but lower peak age-hardening strength.

Fabrication Properties

Weldability

5082 is highly weldable by common fusion processes such as TIG (GTAW) and MIG (GMAW) with predictable bead shape and low hot-cracking tendency. Typical filler metals include 5356 (Al-Mg) and 5183 for better corrosion resistance; these fillers match alloy chemistry to avoid excessive galvanic coupling and to preserve mechanical integrity.

Weld heat-affected zones (HAZ) can exhibit localized softening in heavily strain-hardened tempers, and distortion control is necessary for thin gauges; post-weld mechanical properties generally remain acceptable since the alloy is non-heat-treatable. Preheating is not usually required for moderate thicknesses, but control of interpass temperature and cleaning of oxide films are important for weld quality.

Machinability

5082 is not among the easiest aluminum alloys to machine because of its relatively high magnesium content which can cause built-up edge and gummy chips under inappropriate conditions. Typical machinability indexes are moderate: carbide cutting tools with positive rake, chip breakers, and proper coolant/feed strategies are recommended to maintain surface finish and tool life.

Recommended cutting speeds and feeds depend on section and rigidity, but moderate speeds with heavier feed and reliable chip evacuation produce the best results; abrasive inclusions from impurities can shorten tool life, so machine setups should be validated on production stock.

Formability

Forming performance is best in O temper where deep drawing, stretch forming, and bending produce consistent results with low springback. For strain-hardened tempers such as H32, minimum bend radii increase and formability drops; designers should allow larger bend radii and account for increased springback.

Cold working is the principal strengthening method, and controlled intermediate anneals are used if severe forming is required; warm forming can be considered to improve ductility but must be validated to avoid sensitization and corrosion issues.

Heat Treatment Behavior

5082 is a non-heat-treatable alloy and therefore does not respond to solution treatment/age hardening to produce large strength gains. Attempts to apply T-style precipitation treatments will not yield the strengthening seen in 6xxx or 7xxx alloys because Mg in 5xxx series alloys forms solid-solution and dispersoid structures rather than strengthening precipitates.

Work hardening and strain aging are the primary mechanisms to adjust mechanical properties; cold work increases strength while annealing (O temper) restores ductility. For parts requiring stable service properties after welding or forming, temper stabilization (e.g., H116) and controlled strain-hardening sequences are standard practice to manage mechanical property changes.

High-Temperature Performance

5082 strength begins to decline progressively with increasing temperature; above about 100–150 °C the usable yield strength drops notably, and prolonged exposure accelerates microstructural changes that can reduce corrosion resistance. Continuous service temperatures are typically limited to below ~100 °C for structural applications; intermittent exposure to higher temperatures (e.g., short-term welding) is acceptable if followed by proper processing.

Oxidation of aluminum at engineering temperatures is limited by the protective oxide layer, but tensile and fatigue properties degrade faster than oxidation; the alloy's HAZ near welds is particularly sensitive to high local temperatures which can reduce mechanical performance. Careful thermal management and design for thermal expansion are important when using 5082 in elevated-temperature environments.

Applications

Industry	Example Component	Why 5082 Is Used
Automotive	Fuel tanks, trailer panels	Good corrosion resistance, formability, moderate strength
Marine	Hulls, decks, superstructure	Excellent seawater corrosion resistance and weldability
Aerospace	Fittings, brackets	Good strength-to-weight for non-critical primary structures
Electronics	Enclosures, heat spreaders	Adequate thermal conductivity with corrosion protection
Pressure Vessels / Cryogenics	Tanks, piping	Toughness at low temperatures and weldability

5082’s combination of cold-worked strength, toughness at low temperature, and resistance to seawater corrosion makes it a mainstay for marine structures, transportation fuel systems, and storage vessels. It is often specified where welding and forming are required without post-weld heat treatment, and where corrosion resistance is a key driver in material selection.

Selection Insights

For engineers deciding between 5082 and softer commercial-purity aluminum (e.g., 1100), 5082 trades higher strength and much better structural performance for somewhat reduced electrical conductivity and slightly lower formability. Choose 5082 when strength and corrosion resistance are more critical than maximizing conductivity or the absolute ease of forming.

Compared with work-hardened alloys like 3003 or 5052, 5082 sits at a higher strength tier while retaining similar—or improved—marine corrosion resistance; it is the choice when design loads exceed the capability of these lower-strength alloys but full heat-treatable strength is not practical.

Against heat-treatable alloys such as 6061 or 6063, 5082 will not reach the same peak tensile strength but is favored when superior weldability, better seawater corrosion resistance, and reduced susceptibility to post-weld aging issues are required. Select 5082 when corrosion exposure and welded structure integrity outweigh the need for maximum age-hardened strength.

Closing Summary

5082 remains a practical, widely used aluminum alloy that balances elevated non-heat-treatable strength, strong seawater corrosion resistance, and robust weldability; these attributes keep it relevant for marine, transportation, and storage applications. Its predictable cold-work behavior and availability in many product forms make it a go-to choice when designers need reliable structural performance without the complexities of heat-treatment processes.