Aluminum 5356: Composition, Properties, Temper Guide & Applications

Comprehensive Overview

5356 is a member of the 5xxx series aluminum alloys (Al–Mg family), nominally containing about 4.5–5.5% magnesium and minor amounts of manganese and chromium. As a 5xxx-series alloy it is non-heat-treatable and derives its strength primarily from solid-solution strengthening and strain hardening rather than precipitation heat treatment.

Key traits of 5356 include relatively high strength for a wrought Al–Mg alloy, excellent weldability (commonly supplied and used as welding filler alloy ER5356), good resistance to general corrosion and seawater, and reasonable formability in annealed and partially hardened tempers. Typical industries that use 5356 are marine and shipbuilding, pressure vessels, transportation and automotive structures, architectural panels, and as filler material for welding of Al alloys.

Engineers select 5356 when a balance of weldable, corrosion-resistant, and stronger-than-commercially-pure performance is required, especially for welded assemblies in marine or chloride-exposed environments. It is frequently chosen over lower-strength alloys when welded joint strength and resistance to seawater corrosion are priorities, and over some heat-treatable alloys when post-weld heat treatment is impractical or when solid-solution stability under cyclic service is important.

Temper Variants

Temper	Strength Level	Elongation	Formability	Weldability	Notes
O	Low	High	Excellent	Excellent	Fully annealed; best for deep drawing and forming
H111	Moderate	Moderate-High	Good	Excellent	Partially strain-hardened; common for extrusions
H112	Moderate-High	Moderate	Good	Excellent	Permanent set through controlled processing
H14	Moderate-High	Moderate	Fair-Good	Excellent	Quarter-hard — increased strength by cold work
H24	High	Low-Moderate	Limited	Excellent	Strain-hardened and partially annealed for toughness
H32 / H34	High	Low	Limited	Excellent	Strain-hardened and stabilized; used where springback control needed

Tempers in 5356 are achieved by combinations of cold work and stabilization, not by solution/aging cycles. Moving from O to progressively higher H-numbers increases strength and decreases elongation and formability; weldability remains good across the temper range because the alloy does not rely on heat treatment to develop strength.

Chemical Composition

Element	% Range	Notes
Si	≤ 0.25	Low silicon keeps solidification range narrow and reduces brittle intermetallics.
Fe	≤ 0.40	Typical impurity; excessive iron can degrade ductility and increase inclusion content.
Mn	0.20–0.60	Controls grain structure and contributes modestly to strength and corrosion resistance.
Mg	4.5–5.5	Principal alloying element; provides solid-solution strengthening and corrosion performance.
Cu	≤ 0.10	Kept low since copper reduces corrosion resistance in marine environments.
Zn	≤ 0.20	Low zinc preserves galvanic behavior versus steel and other Al alloys.
Cr	0.05–0.25	Added to control grain growth and improve resistance to sensitization during thermal exposure.
Ti	≤ 0.15	Grain refiner when present in small amounts.
Others (each)	≤ 0.05	Residuals and trace tramp elements; controlled to maintain consistent properties.

The chemistry of 5356 emphasizes magnesium to achieve solid-solution strengthening and improved seawater resistance while limiting copper and zinc to retain corrosion performance. Manganese and chromium are used in controlled amounts to refine microstructure and reduce susceptibility to grain-boundary related corrosion during thermal cycles.

Mechanical Properties

Tensile behavior of 5356 is dominated by solid-solution strengthening from magnesium and by the degree of cold work imparted in the tempering step. In annealed condition the alloy exhibits ductile fracture with relatively high elongation, while in strain-hardened tempers the tensile strength increases significantly at the cost of reduced elongation. Thickness and finishing (rolling vs extrusion) have measurable effects: thinner sections and heavily worked extrusions typically show higher yield and ultimate strength due to greater cold-work and finer microstructure.

Yield strength and elongation are temper- and thickness-dependent; higher H-temper states increase yield and ultimate strength but lower uniform and total elongation. Hardness correlates with the cold-work level and is commonly reported as Vickers or Brinell values that rise with progressively higher H-numbers. Fatigue performance is generally favorable for 5356 in seawater and atmospheric environments, but welded joints and heat-affected zones must be designed to avoid stress concentration and tensile residual stresses that lower fatigue life.

Property	O/Annealed	Key Temper (e.g., H111/H14)	Notes
Tensile Strength (MPa)	180–240	240–320	Values vary with thickness and specific H-temper; listed ranges are typical for wrought product.
Yield Strength (MPa)	70–140	150–260	Work-hardened tempers show elevated yield correlated with cold reduction.
Elongation (%)	18–30	6–18	Annealed exhibits highest ductility; strain-hardened tempers reduce elongation.
Hardness (HB)	35–60	60–95	Hardness increases roughly linearly with cold work; values are indicative for common tempers.

Physical Properties

Property	Value	Notes
Density	~2.66 g/cm³	Typical for Al–Mg alloys; useful for strength-to-weight calculations.
Melting Range	~570–645 °C	Solidus–liquidus range depends on alloying and inclusion levels; eutectics minimal.
Thermal Conductivity	~120–150 W/m·K	Lower than pure aluminum but still good for thermal dissipation applications.
Electrical Conductivity	~28–38 % IACS	Reduced compared to pure Al due to magnesium in solution.
Specific Heat	~0.90 J/g·K (900 J/kg·K)	Typical aluminum specific heat for thermal mass calculations.
Thermal Expansion	~23–24 µm/m·K	Typical coefficient for Al alloys at ambient temperatures.

5356 retains many of aluminum’s attractive physical traits: good thermal conductivity, low density, and easy recyclability. The exact thermal and electrical properties are depressed relative to pure aluminum because of the magnesium content; designers should account for these reductions when specifying for thermal management or electrical-conductivity-critical applications.

Product Forms

Form	Typical Thickness/Size	Strength Behavior	Common Tempers	Notes
Sheet	0.5–6.0 mm	Performance varies with cold roll reduction	O, H111, H14	Widely used for panels and welded fabrications; often clad in architectural uses.
Plate	6–50 mm	Lower work-hardening effect for thick sections	H111, H112	Thicker sections are more difficult to cold work; mechanical properties depend on processing history.
Extrusion	Complex profiles, wall thickness from 1–20 mm	Good strength in formed profiles due to work hardening	H111, H14, H32	Common for structural members and welded frames; good surface finish achievable.
Tube	Ø10–300 mm, wall thickness variable	Strength influenced by extrusion and draw processes	H111, H14	Used for fluid lines, marine railings, and structural tubing; corrosion resistance advantageous.
Bar/Rod	Diameters 3–50 mm	Behavior depends on cold drawing	H111, H14	Also supplied as welding rods/wire (ER5356) for filler applications.

Processing differences between sheet, plate and extrusion are significant: cold rolling and drawing impart strain-hardening that raises strength in thinner products, while plate manufacture tends to produce coarser grains and lower as-fabricated strength. Welding filler availability (rods/wires) is a major reason 5356 is produced in many product forms; this facilitates matched metallurgy for welded assemblies.

Equivalent Grades

Standard	Grade	Region	Notes
AA	5356	USA	Primary wrought alloy designation; ER5356 is common welding filler.
UNS	A95356	International	UNS registry designation corresponding to AA 5356 for engineering specs.
ISO / EN	AlMg5	Europe / International	Generic Al–Mg5 family designation; check local standard for full spec details.
JIS	A5356 (typical)	Japan	Regional numbering varies; verify mechanical and chemical clauses.
GB/T	AlMg5 / 5356	China	Chinese standards often list as AlMg5 with national chemical limits.

Regional standards often use the Al–Mg5 nomenclature for the same nominal chemistry, but limits on trace elements, allowable impurities, and temper designations may differ slightly. ER5356 (welding filler) is a ubiquitous designation across regions, but purchasers should always confirm thickness-dependent properties and any additional processing treatments from the mill certificate.

Corrosion Resistance

5356 exhibits very good general corrosion resistance in atmospheric and marine environments because magnesium in solid solution forms a stable passive film and the alloy contains minimal copper. In seawater and splash zones it performs well for hulls, decks, and fittings when properly detailed and maintained; surface treatments and coatings further extend life. Pitting corrosion is less aggressive than in some high-copper alloys, but crevice corrosion can occur in stagnant chloride-rich environments if deposits or differential aeration cells develop.

Alloys with approximately 5% Mg, including 5356, are more susceptible to sensitization and intergranular corrosion if exposed to temperatures in the 65–160 °C range for extended periods; this is relevant for welded assemblies where thermal excursions and HAZs can lead to localized anodic grain boundaries. Stress corrosion cracking (SCC) is a potential concern under sustained tensile stress in certain environments, particularly where chloride concentration and temperature are elevated, so design must minimize residual tensile stresses and avoid galvanic couples that drive anodic reactions. Compared with 3xxx series and commercially pure aluminum, 5356 trades slightly reduced formability for substantially improved corrosion resistance and strength; compared with some 6xxx heat-treatable alloys, 5356 is often more robust in marine chloride environments.

Fabrication Properties

Weldability

5356 is considered an excellent welding filler and base alloy for most fusion welding processes including GTAW (TIG), GMAW (MIG), and SAW. ER5356 welding wire and rods are commonly specified for joining Al–Mg base metals, and welds typically show good tensile strength and ductility. Hot-cracking risk is low compared with some Al–Si fillers, but weld metal composition and joint design must be controlled; dissimilar welding to high-copper alloys or certain 6xxx series alloys can introduce galvanic and SCC concerns. The HAZ can be softened relative to cold-worked parent material due to recovery of cold work; designers should anticipate local reductions in yield near welds.

Machinability

Machining 5356 is rated as fair to moderate compared with free-machining aluminum alloys; it machines better in softer tempers and with carbide tooling. Recommended tooling are carbide end mills and inserts with moderate rake angles to avoid built-up edge; cutting speeds are relatively high compared to steels, and feeds should be optimized to produce short, controllable chips. Coolant or air blast helps to evacuate chips and control heat; finishing passes and light cuts improve surface finish due to the alloy’s ductility.

Formability

Formability is excellent in the O condition with small bend radii possible; partially strain-hardened tempers reduce formability and increase springback. Typical practical inside bend radii in the annealed state can be as small as 1–2× thickness for sheet operations, while H14–H32 tempers generally require larger radii of 2–4× thickness depending on tooling. For deep drawing or complex stamping, start from O temper and apply controlled work-hardening or stabilize to the desired H-temper after forming.

Heat Treatment Behavior

5356 is a non-heat-treatable aluminum alloy; conventional solution treatment and artificial aging are not used to raise strength. Strength changes are achieved through mechanical deformation (cold work) and, where required, stabilization anneals for stress relief. Typical heat exposure above ~65 °C can lead to some diffusion of magnesium and formation of Mg-rich precipitates at grain boundaries (sensitization) which impacts corrosion resistance; therefore, post-fabrication thermal cycles should be minimized or controlled.

Annealing (O temper) softens the alloy by recovery and recrystallization, restoring ductility and formability. Stabilization treatments (low-temperature anneals) are sometimes applied to reduce residual stresses after forming or welding, but these do not produce the strengthening seen in precipitation-hardened aluminum alloys. Design and process controls therefore rely on cold work schedules and control of thermal exposure rather than T-temper cycles.

High-Temperature Performance

Like most Al–Mg alloys, 5356 experiences meaningful strength loss at elevated temperatures; continuous service temperatures are typically limited to about 100–120 °C for load-bearing components. Above ~150 °C the alloy undergoes microstructural recovery and grain-boundary precipitation that reduce mechanical properties and may increase susceptibility to intergranular corrosion. Oxidation in air is minimal compared with steels, but long-term high-temperature exposure accelerates microstructural changes that degrade fatigue and SCC resistance.

Weld heat-affected zones are particularly important under high-temperature applications, since thermal cycles can both soften cold-worked parent material and accelerate sensitization processes at grain boundaries. For short-term elevated-temperature exposures typical of welding or forming operations the effect is usually manageable; for sustained high-temperature service, a different alloy class should be considered.

Applications

Industry	Example Component	Why 5356 Is Used
Marine	Hull plating, railings, deck hardware, fittings	Excellent seawater corrosion resistance and weldability; common filler for weld repairs
Transportation	Structural frames, fuel tanks, trailers	Good strength-to-weight ratio and robust welded joints
Aerospace & Defense	Secondary structures, brackets, fittings	Favorable combination of weldability, fatigue resistance, and corrosion performance
Pressure Vessels / Cryogenics	Storage tanks, welded vessels	Reliable weld filler and stable properties at low temperatures
Welding / Fabrication	Welding rods/wires (ER5356), cladding	ER5356 widely used as filler for Al–Mg and Al–Si base alloys
Architecture	Curtain walls, canopy panels	Corrosion resistance and anodizing compatibility for durable appearance

5356’s role in modern engineering is often focused around welded assemblies where a corrosion-resistant, weldable filler or base alloy is required. The alloy’s combination of formability (in O condition), strength (in H tempers), and availability as welding consumable makes it a practical choice across multiple sectors.

Selection Insights

For designs requiring better strength than commercially pure aluminum (e.g., 1100) while retaining good weldability and corrosion resistance, 5356 is a logical step up; it sacrifices some electrical and thermal conductivity for higher mechanical performance. Compared with work-hardened alloys such as 3003 or 5052, 5356 generally offers higher strength and better seawater corrosion resistance, though 5052 retains very good formability and may be preferable where deep drawing is primary. Against heat-treatable alloys like 6061/6063, 5356 is chosen when post-weld or in-service heat treatment is impractical, or when superior chloride resistance is required despite a lower peak strength capacity.

Select 5356 when welded joint properties and marine corrosion resistance are primary drivers, when use of a magnesium-bearing filler alloy improves joint metallurgy, or when a non-heat-treatable processing route is preferred. If maximum strength per weight is the overriding requirement and post-fabrication heat treatment is acceptable, a T6 heat-treatable alloy may offer higher ultimate strength; if deep drawing is the core requirement, a softer alloy such as O-temper 3xxx series might be preferable.

Closing Summary

5356 remains a widely used and relevant Al–Mg alloy because it delivers an effective balance of weldability, corrosion resistance, and mechanically useful strength without relying on heat-treatment processes. Its common availability as both wrought product and welding consumable (ER5356) makes it a practical choice for engineers addressing welded structures in marine, transportation, and architectural applications where reliable performance and service life in chloride environments are essential.