GNEE 5083 H116 Marine-Grade Aluminium Plate is a high-strength, corrosion-resistant alloy widely used in shipbuilding and offshore applications, including fishing boats, workboats, ferries, and structural marine components. Its combination of mechanical performance, excellent weldability, and superior seawater corrosion resistance makes it a preferred choice for boat builders and marine engineers.
Features and Functions
Excellent seawater corrosion resistance: Ideal for hulls, decks, and superstructures exposed to marine environments
High strength: Stronger than many common 5xxx series alloys (e.g., 5052), allowing for thinner, lighter structures
Good weldability: Compatible with MIG (GMAW), TIG (GTAW), and submerged arc welding, supporting strong welded joints
Workability: Suitable for bending, roll-forming, machining, and hull plating applications
Good fatigue resistance: Performs well under cyclic loading from waves and engine vibrations
Repairable and recyclable: Supports lifecycle maintenance and sustainability
Typical Marine Applications
Small to medium fishing boat hulls and decks
Patrol boats, rescue craft, and recreational vessels
Workboats, supply vessels, and crew transfer boats
Hull stringers, frames, bulkheads, and structural members
Superstructures, deckhouses, and components exposed to harsh marine environments
Standards & Specifications
ASTM B928 / B928M - Aluminum-Alloy Plate, Sheet, and Strip for Marine Applications
EN 485-2 / EN 573 / EN 545 - European standards for composition and mechanical properties
ISO 6361 - Wrought aluminium and aluminium alloys (sheets, strips, plates)
Classification Societies: ABS, DNV-GL, Lloyd's Register
Chemical Composition (Typical Limits, wt%)
| Element | Typical | Standard Range |
|---|---|---|
| Aluminum (Al) | Balance | Balance |
| Magnesium (Mg) | 4.0 – 4.9 | 4.0 – 4.9 |
| Manganese (Mn) | 0.4 – 1.0 | 0.4 – 1.0 |
| Chromium (Cr) | 0.05 – 0.25 | 0.05 – 0.25 |
| Iron (Fe) | ≤ 0.40 | ≤ 0.40 |
| Copper (Cu) | ≤ 0.10 | ≤ 0.10 |
| Zinc (Zn) | ≤ 0.25 | ≤ 0.25 |
| Titanium (Ti) | ≤ 0.15 | ≤ 0.15 |
| Others (each) | ≤ 0.05 | ≤ 0.05 |
| Others (total) | ≤ 0.15 | ≤ 0.15 |
Typical commercial 5083 contains ~4.5% Mg, ~0.7% Mn, and low Cr for grain control and corrosion resistance. Exact values depend on standards and mill certificates.
Mechanical Properties (Typical by Temper)
| Property | H111 (near-annealed) | H112 / O | H116 / H321 | H32 / H116 variants |
|---|---|---|---|---|
| Tensile Strength (MPa) | 290 – 330 | 275 – 305 | 305 – 355 | 300 – 350 |
| Yield Strength 0.2% (MPa) | 130 – 200 | 125 – 190 | 145 – 275 | 145 – 260 |
| Elongation (%) | 10 – 22 | 12 – 25 | 8 – 20 | 9 – 20 |
| Hardness (HB) | ~60 – 80 | ~55 – 75 | ~70 – 95 | ~65 – 90 |
Values vary with plate thickness, temper, and standard. H116/H321 are widely used in hull plates for improved stress-corrosion cracking (SCC) resistance.
Tempering and Heat Treatment
5083 is non-heat-treatable; strength is achieved by cold working and stabilization. Common tempers include:
| Temper | Description | Common Use |
|---|---|---|
| O (annealed) | Softened by solution heat treatment | Forming, deep drawing |
| H111 | Slightly strain-hardened | Moderate forming |
| H112 | As-fabricated | General plate supply |
| H116 / H321 | Strain-hardened and thermal-stabilized | Marine hulls - improved SCC resistance |
| H32 | Strain-hardened and stabilized | Moderate strength and formability |
H116 or stabilized tempers are preferred for marine use to resist intergranular corrosion and stress-corrosion cracking after welding.
Welding and Fabrication
Welding methods: MIG (GMAW), TIG (GTAW), Submerged Arc (SAW), spot welding
Filler alloys: ER5356 recommended; ER5183 as alternative
Preheat: Not typically required; monitor thickness and joint design
Post-weld: HAZ strength may reduce; stabilized tempers maintain corrosion resistance
Bending/Forming: Use proper bend radii according to temper and thickness to avoid cracking
Corrosion Resistance
Excellent seawater and marine atmosphere resistance due to high Mg content and controlled impurities
Resistant to general corrosion and pitting; stabilized H116/H321 tempers help prevent SCC
Protective coatings (paint, anodizing) and sacrificial anodes (zinc/aluminium) commonly used
Plate Thickness and Formats
| Application | Typical Thickness (mm) |
|---|---|
| Small boat hull plating | 2 – 6 |
| Commercial fishing vessel hulls | 4 – 12 |
| Workboats / Patrol boats | 6 – 20 |
| Structural members / frames | 6 – 50+ |
Thickness selection depends on vessel size, classification, and loading. Plates are supplied mill-finished, shot-blasted, or coated as required.
Physical Properties
| Property | Typical Value |
|---|---|
| Density | 2.66 – 2.70 g/cm³ |
| Melting Range | 590 – 650 °C |
| Modulus of Elasticity | ~69 GPa |
| Thermal Conductivity | 120 – 140 W/m·K |
| Electrical Conductivity | 34 – 36 % IACS |
| Coefficient of Thermal Expansion (20–100 °C) | 23.5 × 10⁻⁶ /°C |
Design and Structural Considerations
Account for rolling-induced anisotropy and HAZ softening in welded areas
Fatigue design: include crack-stopping features and conservative detailing
Use compatible fasteners to avoid galvanic corrosion
Apply protective coatings, ensure proper drainage, and maintain cathodic protection
Quality Control and Testing
Mill Test Certificate (MTC): Chemical and mechanical test reports for each batch
Non-destructive testing (NDT): UT for thickness/defects; dye penetrant for surface cracks; radiography if required
Mechanical tests: Tensile, hardness, and corrosion per classification society standards
Welding certification: WPS/PQR and qualified welders per EN ISO 9606, ASME
Example Specification
Alloy: 5083
Temper: H116 (stabilized)
Thickness: 4 mm (example)
Plate size: Up to 3000 mm width × custom length
Surface finish: Mill finish or shot-blasted
Chemical verification: EN 573 / ASTM B928
Mechanical properties: Yield ≥145 MPa, Tensile ≥300 MPa
Welding filler: 5356 (or per spec)
Certification: MTC EN 10204 3.1 / classification society as required
Advantages vs. Competing Materials
Vs. mild steel: ~1/3 weight, superior corrosion resistance, easier fabrication; requires careful fatigue design
Vs. 6061 aluminium: Better seawater corrosion resistance and weldability; 6061 may be stronger in heat-treated forms
Vs. composites/GRP: Superior impact resistance, recyclability, repairability; composites may be lighter for complex shapes
Handling, Storage, and Maintenance
Store plates flat, ventilated, off the ground, away from dissimilar metals
Avoid alkaline/acidic contact and iron/steel contamination
Inspect for pitting, crevice corrosion, and fastener integrity; maintain coatings and anode systems
GNEE 5083 H116 aluminium plate provides a high-strength, corrosion-resistant, weldable, and fatigue-resistant solution for marine hulls, superstructures, offshore vessels, and structural marine components, ensuring durability and reliability in harsh seawater environments.
