H112
As-rolled with minimal controlled strain hardening; mechanical properties are guaranteed but no corrosion test is required. The usual delivery condition for 5A30 to GB/T 22641.
High-strength marine plate
5A30 and 5456 Marine Grade Aluminium Plate
5A30 (GB/T 3190) and 5456 (Aluminum Association) are near-identical aluminium alloys with 4.7 – 5.5 % magnesium, manganese and chromium, giving more strength than 5083 in welded hull and deck plate. 5A30 is supplied mainly as H112 plate to GB/T 22641; 5456 is supplied in H116 and H321 to ASTM B928 with corrosion testing for naval and commercial ships. Metline supplies both, cut to size and certified, worldwide.
- Alloys
- 5A30 · 5456 (Al-Mg5-Mn-Cr)
- Tempers
- H112 · H116 · H321 · O
- Thickness
- 6 – 50 mm
- Standards
- GB/T 22641 · ASTM B928
Two names for one high-strength marine alloy
5456 was developed in the United States as a stronger alternative to 5083 for welded naval structures, and it remains a standard hull, deck and armour plate for patrol boats, landing craft and military vehicles. China's GB/T 3190 registers 5A30 with practically the same composition: 4.7 – 5.5 % magnesium, 0.5 – 1.0 % manganese and a small chromium addition. Buyers often see the two names together, and for most purposes they are interchangeable.
The extra magnesium compared with 5083 lifts strength by roughly 5 – 10 % in matching tempers, and welds made with ER5556 filler keep that advantage. The alloy also has good fatigue and impact behaviour, which is why it has been used for armour plate and blast-resistant panels as well as hulls.
The difference between the names shows up in how the plate is delivered. 5A30 is usually supplied as-rolled H112 plate to GB/T 22641, the Chinese standard for aluminium ship plate. 5456 for international marine service is normally ordered in the special H116 or H321 tempers to ASTM B928, which require each lot to pass exfoliation (ASTM G66) and intergranular corrosion (ASTM G67) tests. If your vessel is classed by DNV, ABS, Lloyd's Register or Bureau Veritas, those tested tempers are what the surveyor will expect.
Chemical composition: 5A30 and 5456 (wt %)
| Element | 5A30 (GB/T 3190) | 5456 (Aluminum Association) |
|---|---|---|
| Magnesium (Mg) | 4.7 – 5.5 | 4.7 – 5.5 |
| Manganese (Mn) | 0.50 – 1.0 | 0.50 – 1.0 |
| Chromium (Cr) | 0.05 – 0.20 | 0.05 – 0.20 |
| Silicon (Si) | Si + Fe ≤ 0.40 | ≤ 0.25 |
| Iron (Fe) | (combined above) | ≤ 0.40 |
| Copper (Cu) | ≤ 0.10 | ≤ 0.10 |
| Zinc (Zn) | ≤ 0.25 | ≤ 0.25 |
| Titanium (Ti) | 0.03 – 0.15 | ≤ 0.20 |
| Aluminium (Al) | Remainder | Remainder |
The only meaningful difference is that 5A30 caps silicon and iron together at 0.40 % and sets a minimum titanium level. Both grades comfortably meet the low-copper requirement that marine alloys need.
Mechanical properties by temper
| Alloy and temper | Thickness (mm) | Tensile strength Rm | Proof strength Rp0.2 | Elongation |
|---|---|---|---|---|
| 5A30 H112, GB/T 22641 minimum | 6 – 50 | ≥ 310 MPa | ≥ 175 MPa | ≥ 13 % |
| 5456 H116 / H321, ASTM B928 minimum | about 6.3 – 30 | ≥ 317 MPa (46 ksi) | ≥ 228 MPa (33 ksi) | about 10 % or more |
| 5456 H116, typical | — | about 350 MPa | about 255 MPa | about 16 % |
| 5456 O, typical | — | about 310 MPa | about 160 MPa | about 24 % |
ASTM B928 minimums fall slightly in thicker bands. Exact values for your thickness appear on the mill certificate.
Physical properties (typical)
- Density
- 2.66 g/cm³
- Elastic modulus
- about 71 GPa
- Thermal conductivity
- about 115 – 120 W/m·K
- Coefficient of thermal expansion
- about 23.9 µm/m·°C
- Melting range
- about 570 – 640 °C
H112, H116 and H321 explained
H116
Strain-hardened with controlled processing to produce a microstructure resistant to exfoliation and intergranular corrosion. Tested to ASTM G66 and G67 under ASTM B928.
H321
Strain-hardened and thermally stabilised, again with B928 corrosion testing. Strength is similar to H116; the choice usually follows the shipyard's practice or the rules.
O
Fully annealed for maximum formability, used where plate must be pressed or rolled to tight curvature.
Plate sizes and weights
Supply range
- Thickness
- 6 – 50 mm; thinner sheet in O temper on request
- Common sizes
- 1250 × 2500, 1500 × 3000, 2000 × 8000 mm; wider plates to reduce seams
- Cutting
- Cut to size or to a nesting plan
- Surface
- Mill finish, PVC film or interleaving paper
| Thickness (mm) | kg per m² | 1250 × 2500 mm (kg) | 1500 × 3000 mm (kg) | 2000 × 6000 mm (kg) |
|---|---|---|---|---|
| 6 | 15.96 | 49.9 | 71.8 | 192 |
| 8 | 21.28 | 66.5 | 95.8 | 255 |
| 10 | 26.60 | 83.1 | 119.7 | 319 |
| 12 | 31.92 | 99.8 | 143.6 | 383 |
| 15 | 39.90 | 124.7 | 179.6 | 479 |
| 20 | 53.20 | 166.2 | 239.4 | 638 |
| 25 | 66.50 | 207.8 | 299.2 | 798 |
| 30 | 79.80 | 249.4 | 359.1 | 958 |
| 40 | 106.40 | 332.5 | 478.8 | 1277 |
| 50 | 133.00 | 415.6 | 598.5 | 1596 |
Welding and fabrication
Filler choice
ER5556 is the matching filler for 5456 and gives the highest weld strength; ER5183 is also widely used. Avoid ER5356 for primary structure.
Weld design
Welds in H116 plate fall back towards O-temper strength in the heat-affected zone; class rules give reduced welded design values.
Temperature limit
As with all alloys above 3 % Mg, keep long-term service below about 65 °C to avoid sensitisation.
Forming
Bend radii of about 1.5 – 3 × thickness for H116 plate; form tighter curves in O temper.
Cutting
Waterjet, plasma or sawing; remove plasma-affected edges on critical joints.
Protection
Unpainted plate performs well above and below the waterline; antifouling must be copper-free or applied over a barrier coat.
Applications
- Hull shell and decks of patrol boats, crew boats, ferries and landing craft
- Armour and protective panels on vessels and military vehicles
- Superstructures on steel ships, often joined through structural transition joints
- Fuel and water tanks and pressure vessels
- Rail and road tankers needing high welded strength
Joining aluminium superstructures to steel hulls is usually done with explosion-bonded transition strip; see our aluminium-steel transition joint page.
5456 / 5A30 versus 5083 and 5059
| Grade (H116) | Min. Rm | Min. Rp0.2 | Relative availability |
|---|---|---|---|
| 5083 | 305 MPa | 215 MPa | Very high |
| 5456 / 5A30 | 317 MPa | 228 MPa | Moderate |
| 5059 | 370 MPa | 270 MPa | Moderate |
5456 gives a modest strength gain over 5083; 5059 gives a larger one. Many yards choose 5083 for availability and use 5456 or 5059 only where plate thickness and weight must be reduced.
How to order
- SpecifyAlloy, temper, thickness, sizes, quantity, standard (GB/T 22641 or ASTM B928) and class society.
- QuoteWe confirm availability, test requirements and delivery terms (EXW, FOB, CIF or DAP).
- ProcessPlates cut to size, protected and inspected.
- DocumentEN 10204 3.1 certificate with chemistry, tensile and any corrosion test results.
- ShipSeaworthy wooden cases or pallets for sea freight.
References and standards
- ASTM B928 – High Magnesium Aluminum-Alloy Sheet and Plate for Marine Service
- ASTM G66 (ASSET) and ASTM G67 (NAMLT) – corrosion tests for 5xxx alloys
- GB/T 22641 – Aluminium alloy plates for ships
- GB/T 3190-2020 – Chemical composition of wrought aluminium and aluminium alloys
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
5A30 and 5456 marine aluminium (aluminum) plate: FAQs
Is 5A30 the same as 5456?
Practically yes. Both have 4.7 – 5.5 % Mg, 0.5 – 1.0 % Mn and 0.05 – 0.20 % Cr. 5A30 limits Si + Fe to 0.40 % combined and sets a minimum titanium content.
What is the difference between 5456-H116 and H321?
Both are strain-hardened tempers tested for exfoliation and intergranular corrosion to ASTM B928. H321 includes a thermal stabilisation step; strengths are similar.
Which filler wire is used for 5456?
ER5556 is the matching filler; ER5183 is also common. Both give higher weld strength than ER5356.
Is 5456 stronger than 5083?
Slightly: ASTM B928 minimums for H116 plate are about 317 / 228 MPa for 5456 against 305 / 215 MPa for 5083.
How much does a 20 mm 5456 plate weigh?
About 53.2 kg per m², or roughly 239 kg for a 1500 × 3000 mm plate.
Specifying 5A30 or 5456 plate?
Send alloy, temper, sizes, class requirements and destination; we will reply with availability, certification and a delivered price.
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