Aluminium plate marine grade

2026-02-10 18:18:56

Marine environments are uniquely punishing: salt spray, humidity, temperature cycling, abrasion, and galvanic couples all work together to attack metal. Aluminium plate marine grade is engineered to thrive in these conditions by combining corrosion resistance, strength-to-weight efficiency, and dependable fabrication performance. For boatbuilders, shipyards, offshore contractors, and coastal infrastructure projects, marine-grade aluminium plate offers a practical path to long service life with reduced maintenance compared to many steels.

What "Marine Grade" Means

In aluminium plate, marine grade generally refers to alloys that have demonstrated strong resistance to seawater corrosion and retain good mechanical properties after welding. In practice, the most common marine-grade plate families are:

5xxx series (Al-Mg) such as 5083, 5086, 5454, 5754
Selected 6xxx series (Al-Mg-Si) such as 6061, 6082 (often for extrusions and structural components; plate is also used)

For immersed or splash-zone service, 5xxx alloys dominate because of their excellent resistance to chloride-driven corrosion and strong weldability. For machined structural parts where higher yield strength and heat-treat capability are valuable, 6xxx alloys are often chosen-typically with added attention to corrosion design and isolation from dissimilar metals.

Features Customers Value

Feature	What it means in service	Typical benefit
Seawater corrosion resistance	Strong resistance to pitting and general corrosion in chloride environments	Longer life, less coating dependency
High strength-to-weight	Good mechanical strength at low density	Faster vessels, higher payload, easier handling
Weldability	Stable properties and low defect sensitivity in welded structures	Efficient fabrication, reliable joints
Toughness at low temperature	Maintains toughness in cold marine climates	Safer structures in harsh regions
Formability	Good bending and forming for hull plating and superstructures	Cleaner fabrication, fewer seams
Recyclability	Aluminium is widely recycled with high retained value	Better lifecycle economics

Common Marine-Grade Alloys and Tempers

Marine plate is usually supplied in tempers that balance strength, workability, and stress-corrosion performance.

Alloy	Alloy family	Common tempers (plate)	Typical marine use
5083	Al-Mg-Mn	H116, H111, H321	Hulls, decks, bulkheads, high-performance structures
5086	Al-Mg	H116, H111	Hull plating, tanks, welded assemblies
5454	Al-Mg	H32	Pressure vessels, fuel/chemical tanks, heat-affected zones with good stability
5754	Al-Mg	H111, H22/H24	Superstructures, interior panels, general marine fabrication
6061	Al-Mg-Si	T6, T651	Machined parts, frames, fittings, structural members
6082	Al-Mg-Si	T6, T651	European structural plate applications, machined components

Temper notes (quick guide)

H116 / H321 are widely used for marine 5xxx plate because they are designed to improve corrosion performance in seawater service while maintaining strength.
T6 / T651 indicate solution heat-treated and artificially aged (with T651 stress-relieved by stretching), often preferred for dimensional stability in machining.

Chemical Composition (Typical Ranges)

Actual limits vary by standard and product form. Confirm exact chemistry to the governing specification for your project.

5083 (Marine Plate Standard Workhorse)

Element	Typical range (wt%)
Mg	4.0–4.9
Mn	0.4–1.0
Cr	0.05–0.25
Si	≤0.40
Fe	≤0.40
Cu	≤0.10
Zn	≤0.25
Ti	≤0.15
Al	Balance

5086 (Excellent Welded Hull Plate)

Element	Typical range (wt%)
Mg	3.5–4.5
Mn	0.2–0.7
Cr	0.05–0.25
Si	≤0.40
Fe	≤0.50
Cu	≤0.10
Zn	≤0.25
Ti	≤0.15
Al	Balance

6061 (Structural, Machinable Marine Component Plate)

Element	Typical range (wt%)
Mg	0.8–1.2
Si	0.4–0.8
Cu	0.15–0.40
Cr	0.04–0.35
Fe	≤0.70
Mn	≤0.15
Zn	≤0.25
Ti	≤0.15
Al	Balance

Mechanical Properties (Typical Values)

Properties depend on thickness, orientation, and standard. The values below are representative for common supply conditions.

Alloy / Temper	Tensile strength (MPa)	Yield strength (MPa)	Elongation (%)	Notes
5083-H116	305–350	215–250	10–16	Excellent hull plate choice
5083-H321	305–350	215–250	10–16	Stable for welded structures
5086-H116	275–340	200–240	10–16	Very good welded performance
5754-H111	190–240	80–130	12–22	Great formability, moderate strength
6061-T6 / T651	290–320	240–280	8–12	Strong, machinable; corrosion design matters

Technical Specifications Customers Commonly Request

Dimensional Supply (Typical Capabilities)

Availability varies by mill and region; these ranges reflect common stocking and production practice.

Parameter	Typical range
Thickness	3–150 mm (stock); thicker plate may be available by inquiry
Width	1000–2500 mm
Length	2000–12000 mm
Flatness	Controlled by plate class; tighter tolerances available
Surface finish	Mill finish; optional brushed or patterned finishes
Protection	PVC film, paper interleaving, export seaworthy packing

Physical Properties (Useful for Design)

Property	Typical value (5xxx marine plate)	Typical value (6061)
Density	~2.66–2.68 g/cm³	~2.70 g/cm³
Thermal conductivity	~110–140 W/m·K	~167 W/m·K
Electrical conductivity	Moderate	Moderate
Melting range	~570–640 °C	~582–652 °C

Performance in Marine Corrosion Conditions

Marine-grade aluminium plate resists corrosion primarily through a stable oxide film and the alloy's chemistry. In real-world marine service, performance is strongly influenced by design and fabrication practices.

Marine exposure zone	Typical risk	Recommended alloy family
Immersed seawater	Pitting, crevice corrosion	5xxx (5083/5086/5454)
Splash / tidal zone	Wet-dry cycling, chloride concentration	5xxx preferred; good detailing and drainage essential
Atmospheric coastal	Salt spray, staining	5xxx or 6xxx with good coating/anodizing practice
Dissimilar metal contact	Galvanic corrosion	Any alloy needs isolation strategy

Fabrication, Welding, and Finishing Notes

Topic	Practical guidance for customers
Welding	5xxx plate welds efficiently with common marine filler choices; control heat input and cleanliness for best results
Heat treatment	5xxx is non-heat-treatable; strength is from work hardening. 6xxx is heat-treatable and often supplied in T6/T651
Forming	5754 and 5086 are very friendly for bending; 5083 offers strong performance with slightly higher forming loads
Machining	6061-T651 is often preferred for tight tolerances and stable machining
Surface protection	Marine coatings and anodizing improve durability; even "marine grade" benefits from good coating design
Galvanic isolation	Use insulating gaskets, sleeves, coatings, and proper fastener selection when joining to steel, copper alloys, or carbon composites

Typical Applications

Application	Why marine aluminium plate fits
Boat and ship hulls	High strength-to-weight, corrosion resistance, weldable large plates
Decks and superstructures	Reduced top weight improves stability and fuel efficiency
Offshore walkways, platforms	Durable in salt-laden air, easy modular fabrication
Fuel, water, and process tanks	Selected 5xxx alloys offer reliable corrosion performance and weld integrity
Gangways, ramps, pontoons	Lightweight handling, strong in service, good repairability
Coastal infrastructure	Ladders, covers, housings, and panels with long service life

How to Specify the Right Plate Quickly

What to decide	Practical recommendation
Primary environment	Immersed/splash zone favors 5083/5086; structural machined parts often favor 6061
Welded or machined?	Heavy welding: 5xxx. Tight machining and fixtures: 6061-T651
Target thickness and flatness	Confirm plate class, tolerances, and stress-relief needs
Certification needs	Request mill test certificate, traceability, and standard compliance for marine projects
Corrosion design	Plan drainage, avoid crevices, isolate dissimilar metals, and consider coatings

Aluminium plate marine grade-commonly 5083-H116/H321 and 5086-H116-is designed for seawater durability, excellent weldability, and high strength-to-weight performance. It is widely used in boat hulls, decks, offshore structures, tanks, and coastal equipment, offering reliable corrosion resistance in immersed and splash-zone environments. With clear alloy selection, proper fabrication, and galvanic isolation, marine-grade aluminium plate delivers lightweight construction, long service life, and lower maintenance in demanding marine conditions.

Lucy

Marine environments are uniquely punishing: salt spray, humidity, temperature cycling, abrasion, and galvanic couples all work together to attack metal.

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