H112
As extruded with guaranteed properties; the normal temper for machined fittings and pins.
Marine · high-magnesium round bar
5456 Marine Aluminium Round Bar
5456 is the strongest of the commonly used weldable aluminium-magnesium alloys, a higher-magnesium cousin of 5083 developed for naval and high-performance hulls. As round bar it is machined into high-load fittings, pins and shafts that must be welded to Al-Mg structure. Metline supplies 5456 round bar in O, H111 and H112, plus 5454 and 5754 for warm-service and general fittings, worldwide.
- Alloy
- 5456 (Al-5.1Mg-0.8Mn)
- Tempers
- O, H111, H112
- Diameter
- Up to about 320 mm
- Standards
- ASTM B221 · EN 755 · GB/T 3191
What makes 5456 different from 5083
5456 has 4.7 – 5.5 % magnesium against 4.0 – 4.9 % in 5083, with similar manganese and chromium. The extra magnesium raises strength by roughly 5 – 15 % in every temper, including in the as-welded condition, which is what designers of lightweight hulls care about most.
The alloy was developed in the US for naval use and has been specified for frigate and cruiser superstructures, patrol craft and high-speed vessels, where every kilogram saved above the waterline improves stability and speed. Bar in 5456 is used for the machined parts of those structures: high-load pad eyes, hinge and davit pins, stanchion bases, shafting and bosses that are welded to 5456 or 5083 plate.
There is a well-known caution. The same high magnesium makes 5456 more prone than 5083 to sensitisation: after long exposure to warm temperatures, β-phase precipitates along grain boundaries and the metal can crack by intergranular and stress corrosion in seawater. Naval experience with sun-heated 5456 superstructures that developed cracking after years in service is the reason modern designs keep 5456 cool, choose corrosion-tested tempers for plate and often switch to 5083 or 5383 where heat exposure is uncertain.
Composition of 5456, 5454 and 5754 (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.
Mechanical properties of 5456 round bar
ASTM B221 minimums for extruded 5456 bar, with 5454 and 5754 for comparison (5754 from EN 755-2). GB/T 3191 gives slightly different values; for example it lists 5456-H112 at 300 MPa tensile. The standard on your order governs acceptance.
| Alloy and temper | Tensile strength Rm | Proof Rp0.2 (min) | Elongation (min) |
|---|---|---|---|
| 5456-O | 285 – 365 MPa | 130 MPa | 14 % |
| 5456-H111 | ≥ 290 MPa | 180 MPa | 12 % |
| 5456-H112 | ≥ 285 MPa | 130 MPa | 12 % |
| 5454-O | 215 – 285 MPa | 85 MPa | 14 % |
| 5454-H112 | ≥ 215 MPa | 85 MPa | 12 % |
| 5754-O / H111 | 180 – 250 MPa | 80 MPa | 14 – 17 % |
| 5754-H112 | ≥ 180 MPa | 80 MPa | 12 – 14 % |
Typical 5456-O bar tests at about 310 MPa tensile and 160 MPa proof with around 24 % elongation. For welded design, the as-welded minimum tensile strength usually quoted for 5456 is about 290 MPa, against about 275 MPa for 5083 and 215 MPa for 5454.
Physical properties (5456)
- Density
- 2.66 g/cm³ (0.096 lb/in³)
- Modulus of elasticity
- About 71 GPa
- Thermal conductivity
- About 116 W/m·K
- Electrical conductivity
- About 29 % IACS
- Coefficient of thermal expansion
- About 23.9 µm/m·°C (20 – 100 °C)
- Melting range
- About 570 – 638 °C
Tempers and the sensitisation question
H111
Annealed and lightly stretched, giving the highest guaranteed proof stress of the bar tempers (180 MPa).
O
Fully annealed for bending, upsetting and cold heading.
H116 / H321
Corrosion-tested tempers for rolled plate under ASTM B928 and IACS UR W25. They do not apply to extruded round bar.
Heat limit
Keep long-term metal temperature below about 65 °C. Avoid hot forming or stress relieving in the 100 – 250 °C range.
Testing for sensitisation
ASTM G67 (nitric acid mass loss) is the standard check. It can be agreed on bar orders where a specification asks for it.
Standards and classification
5456 round bar is ordered to ASTM B221 (extruded), EN 755 or GB/T 3191. For rolled plate, IACS UR W25 lists 5456 in O, H116 and H321, with corrosion testing required for H116 and H321. Its extruded-products table, however, covers only 5083, 5383, 5059 and 5086 among the Al-Mg alloys, so 5456 bar used in a classed structure needs the society's agreement. Naval projects often work to their own specifications, which state the bar standard and tests required.
| System | 5456 | 5454 | 5754 |
|---|---|---|---|
| UNS | A95456 | A95454 | A95754 |
| EN | EN AW-5456 | EN AW-5454 (AlMg3Mn) | EN AW-5754 (AlMg3) |
| Werkstoff | — | 3.3537 | 3.3535 |
| Bar standards | ASTM B221, GB/T 3191 | ASTM B221, EN 755, GB/T 3191 | EN 755 / 754, GB/T 3191 |
Round bar sizes and weights
Supply range
- Diameter
- About 8 – 320 mm extruded
- Length
- 3000, 4000, 6000 mm; cut pieces on request
- Tempers
- O, H111, H112
- Finish
- Mill finish; peeled or turned for large diameters
High-magnesium alloys need high extrusion pressure, so the largest diameters and small quantities of 5456 may take longer to source than 5083.
Weight per metre = π/4 × d² × 2.66 ÷ 1000 kg (d in mm).
| Diameter (mm) | kg per metre | kg per 3 m bar | kg per 6 m bar |
|---|---|---|---|
| 10 | 0.209 | 0.63 | 1.3 |
| 16 | 0.535 | 1.60 | 3.2 |
| 20 | 0.836 | 2.51 | 5.0 |
| 25 | 1.31 | 3.92 | 7.8 |
| 30 | 1.88 | 5.64 | 11.3 |
| 40 | 3.34 | 10.03 | 20.1 |
| 50 | 5.22 | 15.67 | 31.3 |
| 60 | 7.52 | 22.56 | 45.1 |
| 80 | 13.37 | 40.11 | 80.2 |
| 100 | 20.89 | 62.67 | 125.3 |
| 120 | 30.08 | 90.25 | 180.5 |
| 150 | 47.01 | 141.02 | 282.0 |
| 200 | 83.57 | 250.70 | 501.4 |
| 250 | 130.57 | 391.72 | 783.4 |
| 300 | 188.02 | 564.07 | 1128.1 |
Diameter tolerance and straightness
Typical extruded round bar tolerances. 5456 and 5754 sit in the higher-magnesium column; 5454 in the tighter column.
| Diameter (mm) | 5454 | 5456 / 5754 |
|---|---|---|
| 8 – 18 | ±0.22 | ±0.30 |
| over 18 – 25 | ±0.25 | ±0.35 |
| over 25 – 40 | ±0.30 | ±0.40 |
| over 40 – 50 | ±0.35 | ±0.45 |
| over 50 – 65 | ±0.40 | ±0.50 |
| over 65 – 80 | ±0.45 | ±0.70 |
| over 80 – 100 | ±0.55 | ±0.90 |
| over 100 – 120 | ±0.65 | ±1.0 |
| over 120 – 150 | ±0.80 | ±1.2 |
| over 150 – 180 | ±1.00 | ±1.4 |
| over 180 – 220 | ±1.15 | ±1.7 |
| over 220 – 270 | ±1.3 | ±2.0 |
| over 270 – 320 | ±1.6 | ±2.5 |
Form tolerances
- Straightness, normal grade
- About 3 mm per metre up to 80 mm diameter, increasing for larger bars
- Straightness, precision grade
- About 0.8 – 3 mm in any 300 mm and 2 – 6 mm per metre, depending on diameter
- Length
- Plus-only, about +7 to +12 mm for 100 – 320 mm bars
Machining and welding 5456
Machining
Harder than 5083, so chips break a little better, but use the same approach: sharp polished carbide, positive rake and flood coolant.
Welding
ER5556 filler is matched to 5456 strength; ER5183 is an alternative. Keep interpass temperature low and avoid preheat to limit time at sensitising temperatures.
Heat input
Use the lowest practical heat input and short arcs. Multiple repairs in one area increase sensitisation risk.
Galvanic contact
Insulate from stainless pins, bronze bushes and steel; seal faying surfaces.
Coating
Paint or anodise parts exposed to direct sun on deck to reduce metal temperature as well as corrosion.
Inspection
For critical parts, an ASTM G67 test on the lot confirms the material is not sensitised as delivered.
Uses of 5456, 5454 and 5754 round bar
- 5456: naval and patrol-craft fittings, davit and hinge pins, high-load pad eyes, shafting and bosses welded to 5456 or 5083 plate
- 5456: high-speed craft structural fittings where weight saving justifies the higher-strength alloy
- 5454: fittings on fuel, cooling and exhaust-adjacent systems that run above 65 °C
- 5754: stanchions, handrail fittings, ladder rungs and general deck hardware
- All three: offshore and aquaculture hardware, gangway pins and mooring fittings
A typical example is a davit on an aluminium patrol vessel: the arm is a welded 5456 or 5083 fabrication, and the pivot pin and boss are turned from 5456-H112 bar, with a hard-anodised pin surface and an insulating bush where it meets the stainless sheave.
5456 vs 5083 vs 5383 round bar
| Property | 5456-H112 | 5083-H112 | 5383-H112 | 5454-H112 |
|---|---|---|---|---|
| Min tensile (extruded) | 285 MPa | 270 MPa | 310 MPa | 215 MPa |
| Min proof (extruded) | 130 MPa | 110 MPa | 190 MPa | 85 MPa |
| Approx. as-welded tensile | 290 MPa | 275 MPa | Higher than 5083 | 215 MPa |
| Sensitisation risk | Highest | Moderate | Lower than 5083 | Very low |
| Extruded grade in UR W25 | No | Yes | Yes | No |
For new classed designs, 5383 often gives 5456-level strength with better corrosion resistance and an easier approval route. 5456 remains the right choice where a specification requires it or where matching existing 5456 structure.
How to order 5456 round bar
- SpecifyAlloy and temper, diameter and length or cut pieces, quantity and the governing standard with its edition (ASTM B221, EN 755, GB/T 3191 or a naval specification). 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
- IACS UR W25 – Aluminium alloys for hull construction and marine structure
- ASTM B928 – High Magnesium Aluminum-Alloy Sheet and Plate for Marine Service and Similar Environments
- ASTM G67 – Determining the Susceptibility to Intergranular Corrosion of 5XXX Series Aluminum Alloys by Mass Loss after Exposure to Nitric Acid
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
5456 marine aluminium (aluminum) round bar: FAQs
Is 5456 stronger than 5083?
Yes, by about 5 – 15 % depending on temper. Extruded 5456-H112 has a minimum of 285 MPa tensile and 130 MPa proof against 270 and 110 MPa for 5083-H112, and its as-welded strength is also higher.
Why is 5456 used less than 5083 today?
Its higher magnesium makes it more prone to sensitisation and stress-corrosion cracking after long exposure to heat. Many new designs use 5083 or 5383 instead, which give good strength with lower risk and easier class approval for extrusions.
What filler is used to weld 5456?
ER5556 is the matching filler; ER5183 is also used. Keep heat input and interpass temperature low.
Can 5456 round bar be used in an engine room?
Only for parts that stay below about 65 °C. For warm fittings, use 5454 bar.
Is 5456 bar covered by class rules?
IACS UR W25 covers 5456 rolled plate but not 5456 extrusions, so bar used in classed structure needs the society's agreement. It is widely used for fittings and in naval projects with their own specifications.
Can Metline supply 5454 and 5754 bar on the same order?
Yes. We can supply 5456, 5454 and 5754 round bar together, cut and certified to EN 10204 3.1, for delivery worldwide.
Need 5456, 5454 or 5754 round bar?
Send alloy, diameters, temper, quantities and the specification. We will confirm availability, certification and a delivered price.
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