H112
As extruded with guaranteed minimums. Standard for welded and machined square bar.
Marine · Al-Mg square bar
5456, 5454 & 5754 Marine Aluminium Square Bar
Square bar in 5456, 5454 or 5754 gives boatbuilders a solid, weldable aluminium-magnesium section for seatings, chocks, frames and machined blocks, matched to the alloy of the surrounding plate. 5456 gives the most strength, 5454 tolerates warm service and 5754 is the economical general-purpose grade. Metline supplies all three in O, H111 and H112, cut to length and certified, worldwide.
- Alloys
- 5456 · 5454 · 5754
- Tempers
- O, H111, H112
- Side length
- About 10 – 220 mm
- Standards
- ASTM B221 · EN 755 · GB/T 3191
Matching square bar to plate and service
The simplest rule for welded aluminium boats is to keep the whole structure in one alloy family, so welds, plate and fittings corrode alike and one filler wire serves the job. Square bar in 5456, 5454 or 5754 lets a builder do that for the solid parts of a structure.
Each alloy suits a different part of a vessel. 5456 pairs with 5456 or 5083 hull plating where a seating or chock carries heavy load and the space stays cool. 5454 pairs with 5454 tank and casing plate in warm spaces, because it does not become sensitised above 65 °C. 5754 is used with 5754 superstructure and interior plating, and for general deck hardware where strength demands are moderate and cost matters.
Unlike 6xxx square bar, none of these alloys relies on heat treatment, so welding a square bar to plate costs little strength beyond the local annealing of any cold work. That makes them well suited to welded seatings and frames that are fabricated, faired and painted as part of the hull.
Chemical composition (wt %)
| Element | 5456 | 5454 | 5754 |
|---|---|---|---|
| Silicon (Si), max | 0.25 | 0.25 | 0.40 |
| Iron (Fe), max | 0.40 | 0.40 | 0.40 |
| Copper (Cu), max | 0.10 | 0.10 | 0.10 |
| Manganese (Mn) | 0.50 – 1.0 | 0.50 – 1.0 | ≤ 0.50 * |
| Magnesium (Mg) | 4.7 – 5.5 | 2.4 – 3.0 | 2.6 – 3.6 |
| Chromium (Cr) | 0.05 – 0.20 | 0.05 – 0.20 | ≤ 0.30 * |
| Zinc (Zn), max | 0.25 | 0.25 | 0.20 |
| Titanium (Ti), max | 0.20 | 0.20 | 0.15 |
| Others, each / total | 0.05 / 0.15 | 0.05 / 0.15 | 0.05 / 0.15 |
| Aluminium (Al) | Remainder | Remainder | Remainder |
* For 5754, Mn + Cr must total 0.10 – 0.60 %. Limits are the registered Aluminum Association / EN 573-3 values, which IACS UR W25 also uses for 5456 and 5754.
Minimum mechanical properties of square bar
Minimums for extruded square bar. 5456 and 5454 follow ASTM B221; 5754 follows EN 755-2. Some Chinese tables quote single values for "O, H112, all sizes" (for example 5456 at 300 MPa and 130 MPa); use the table from the standard on your order.
| Alloy and temper | Tensile Rm | Proof Rp0.2 | Elongation | Approx. as-welded tensile |
|---|---|---|---|---|
| 5456-O | 285 – 365 MPa | ≥ 130 MPa | ≥ 14 % | About 290 MPa |
| 5456-H112 | ≥ 285 MPa | ≥ 130 MPa | ≥ 12 % | About 290 MPa |
| 5454-O | 215 – 285 MPa | ≥ 85 MPa | ≥ 14 % | About 215 MPa |
| 5454-H112 | ≥ 215 MPa | ≥ 85 MPa | ≥ 12 % | About 215 MPa |
| 5754-O / H111 | 180 – 250 MPa | ≥ 80 MPa | ≥ 14 – 17 % | About 180 – 190 MPa |
| 5754-H112 | ≥ 180 MPa | ≥ 80 MPa | ≥ 12 – 14 % | About 180 – 190 MPa |
As-welded values are indicative figures from welding design codes for butt welds with suitable 5xxx filler; use the values in the code or class rules governing your design.
| Physical property | 5456 | 5454 | 5754 |
|---|---|---|---|
| Density | 2.66 g/cm³ | 2.69 g/cm³ | 2.67 g/cm³ |
| Thermal conductivity | About 116 W/m·K | About 134 W/m·K | About 130 – 140 W/m·K |
| Thermal expansion | About 23.9 µm/m·°C | About 23.6 µm/m·°C | About 23.8 µm/m·°C |
Tempers available
O
Fully annealed, for bars that must be bent to follow hull lines or formed into frames.
H111
Annealed and lightly strain-hardened in straightening; slightly higher proof stress than O.
Not heat-treatable
None of these alloys can be solution treated and aged; T-tempers do not exist for them.
Standards and class acceptance
Square bar in these alloys is ordered to ASTM B221 (extruded), EN 755-2 with EN 755-4 tolerances, or GB/T 3191. IACS UR W25 does not list 5456, 5454 or 5754 for extruded products (it names 5083, 5383, 5059 and 5086), although 5456 and 5754 are listed for rolled plate. For classed structures, agree the use of these bars with the society in advance or choose 5083 or 5383 square bar. For fittings, frames and equipment outside class scope, a 3.1 mill certificate to the product standard is usually sufficient.
| Alloy | UNS | EN designation | Typical marine role |
|---|---|---|---|
| 5456 | A95456 | EN AW-5456 | High-strength welded fittings, naval craft |
| 5454 | A95454 | EN AW-5454 (AlMg3Mn) | Warm-service tanks and frames |
| 5754 | A95754 | EN AW-5754 (AlMg3) | Superstructure, interiors, general hardware |
Square bar sizes and weights
Supply range
- Side length
- About 10 – 220 mm (round-bar equivalent sizes up to about 320 mm)
- Length
- 1000 – 6000 mm; 3, 4 and 6 m standard
- Tempers
- O, H111, H112
- Processing
- Cut to length, deburred, bundled with spacers
Weight per metre = side² × density ÷ 1000 kg. The table uses 5456 (2.66 g/cm³); 5454 is about 1 % heavier.
| Side (mm) | kg per metre | kg per 3 m bar | kg per 6 m bar |
|---|---|---|---|
| 10 | 0.266 | 0.80 | 1.6 |
| 15 | 0.599 | 1.80 | 3.6 |
| 20 | 1.06 | 3.19 | 6.4 |
| 25 | 1.66 | 4.99 | 10.0 |
| 30 | 2.39 | 7.18 | 14.4 |
| 40 | 4.26 | 12.77 | 25.5 |
| 50 | 6.65 | 19.95 | 39.9 |
| 60 | 9.58 | 28.73 | 57.5 |
| 75 | 14.96 | 44.89 | 89.8 |
| 80 | 17.02 | 51.07 | 102.1 |
| 100 | 26.60 | 79.80 | 159.6 |
| 120 | 38.30 | 114.91 | 229.8 |
| 150 | 59.85 | 179.55 | 359.1 |
| 200 | 106.40 | 319.20 | 638.4 |
| 220 | 128.74 | 386.23 | 772.5 |
Square bar tolerances
Typical tolerances for extruded square bar. 5454 is in the lower-magnesium alloy group with tighter limits; 5456 and 5754 use the wider limits.
| Side (mm) | Side tol. 5454 | Side tol. 5456 / 5754 | Corner radius 5454 | Corner radius 5456 / 5754 |
|---|---|---|---|---|
| 10 – 18 | ±0.22 | ±0.30 | 1.0 | 1.5 |
| over 18 – 25 | ±0.25 | ±0.35 | 1.0 | 1.5 |
| over 25 – 40 | ±0.30 | ±0.40 | 1.5 | 2.0 |
| over 40 – 50 | ±0.35 | ±0.45 | 1.5 | 2.0 |
| over 50 – 65 | ±0.40 | ±0.50 | 2.0 | 3.0 |
| over 65 – 80 | ±0.45 | ±0.70 | 2.0 | 3.0 |
| over 80 – 100 | ±0.55 | ±0.90 | 2.5 | 3.0 |
| over 100 – 120 | ±0.65 | ±1.0 | 2.5 | 3.0 |
| over 120 – 150 | ±0.80 | ±1.2 | 2.5 | 4.0 |
| over 150 – 180 | ±1.00 | ±1.4 | 2.5 | 4.0 |
| over 180 – 220 | ±1.15 | ±1.7 | 3.5 | 5.0 |
Form tolerances
- Angle
- Within 1 % of side up to 100 mm; 1.0° to 1.5° above
- Straightness
- 0.8 – 1.5 mm in any 300 mm; 2 – 3 mm per metre overall
- Twist
- 1 – 3° per metre, 3 – 6° over full length, depending on size
- Length
- Plus-only, about +5 to +14 mm
Design and fabrication notes
Filler choice
5456: ER5556 or ER5183. 5454: ER5554 for warm service, ER5356 for cool. 5754: ER5356 or ER5183.
Fillet welds
Size fillet welds on the as-welded strength of the weaker of bar and plate; the bar's H112 strength does not survive in the weld zone.
Fit-up
Square bar sits flush on plate, so root gaps are small. Clean oxide just before welding and keep joints dry.
Machining
Use sharp tools with high rake and coolant; helical-coil inserts for tapped holes that see repeated assembly.
Galvanic isolation
Use insulating pads and sleeves where steel engine feet, stainless bolts or bronze parts bear on the bar.
Heat
Keep 5456 and 5754 seatings away from long-term heat above 65 °C; use 5454 where that cannot be avoided.
Applications on vessels and offshore
- Seatings: engine, generator, pump and winch foundations
- Tank stiffening: 5454 bars on warm fuel and water tanks
- Frames and coamings: hatch and door frames, window surrounds
- Fendering: replaceable rubbing strips on workboats
- Superstructure and interiors: 5754 framing for furniture, partitions and ladders
- Offshore and coastal: pontoon frames, boat landings, aquaculture structures
On a typical aluminium crew-transfer vessel, the deck crane pedestal sits on a 5456 square-bar ring welded to 5083 deck plate, the engine-room fuel day tank is stiffened with 5454 bar, and the wheelhouse furniture frames use 5754, each chosen for its location.
Choosing among the three alloys
| Factor | 5456 | 5454 | 5754 |
|---|---|---|---|
| Magnesium | 4.7 – 5.5 % | 2.4 – 3.0 % | 2.6 – 3.6 % |
| Min tensile, H112 | 285 MPa | 215 MPa | 180 MPa |
| Long-term above 65 °C | Avoid | Suitable | Use with care |
| Formability | Fair | Good | Very good |
| Relative cost and availability | Higher, less common | Moderate | Lower, widely stocked in Europe |
| Matching plate | 5456, 5083 | 5454 | 5754 |
How to order marine square bar
- SpecifyAlloy and temper, side length and length or cut pieces, quantity and the governing standard with its edition (ASTM B221, EN 755 or GB/T 3191). If the vessel is classed, name the society and whether a class certificate is required.
- ConfirmWe confirm the standard and tolerance class can be met, which tests are included (tensile, chemistry, corrosion tests where the standard calls for them) and the delivery terms: EXW, FOB, CIF or DAP.
- InspectMaterial is checked for dimensions, straightness, twist and surface condition before packing; third-party or class surveyor inspection can be arranged on request.
- DocumentEach lot ships with a mill test certificate to EN 10204 3.1 showing the cast analysis and mechanical results, traceable by cast or lot number.
- Pack and shipBars or plates are bundled or cased with moisture protection, marked with alloy, temper, size and lot, and shipped by sea or air to your port or yard.
References and standards
- ASTM B221 – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles and Tubes
- EN 755-2 – Aluminium and aluminium alloys: extruded rod/bar, tube and profiles, mechanical properties
- EN 755-4 – Extruded square bar: tolerances on dimensions and form
- IACS UR W25 – Aluminium alloys for hull construction and marine structure
- EN 573-3 – Aluminium and aluminium alloys: chemical composition and form of wrought products
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
Marine aluminium (aluminum) square bar: FAQs
Which is strongest: 5456, 5454 or 5754 square bar?
5456. Its ASTM B221 minimum in H112 is 285 MPa tensile, against 215 MPa for 5454 and 180 MPa for 5754 (EN 755-2).
Which square bar should I use in a hot engine room?
5454. It does not become sensitised in long service above 65 °C, which 5456 and, to a lesser degree, 5754 can.
Can these square bars be used for classed hull structure?
IACS UR W25 does not list them for extruded products, so use needs the society's agreement. For certified structural square bar, 5083 or 5383 is the usual route.
Do I lose strength when welding square bar to plate?
Only modestly. These alloys are not heat-treated, so the weld zone falls to roughly annealed strength, which for O and H112 is close to the purchased value.
What does a 50 mm 5456 square bar weigh?
About 6.65 kg per metre, or 39.9 kg for a 6 m bar.
Can Metline cut square bar to a list?
Yes. We supply cut pieces to your cutting list with an EN 10204 3.1 certificate and export packing, worldwide.
Need marine square bar in 5456, 5454 or 5754?
Send alloy, sizes, temper and quantities. We will reply with availability, certification and a delivered price.
