Turning and threading
Use sharp, polished carbide with high positive rake, high speed and plenty of coolant. Roll threads where possible; rolled threads in 5xxx alloys have better fatigue resistance than cut threads.
High-magnesium marine hex bar
5059 and 5086 Marine Grade Aluminium Hexagon Bar
Hexagon bar in 5086 or 5059 is the stock for aluminium nuts, couplings, bosses and threaded fittings that must survive seawater and match a high-magnesium hull. 5086 is the readily available, moderate-strength option; 5059 gives roughly twice the extruded yield strength where size and weight are tight. Metline supplies both in IACS-listed extruded tempers, cut to length and certified, worldwide.
- Alloys
- 5059, 5086
- Tempers
- 5059 H112 · 5086 O, H111, H112
- Measured
- Across flats (A/F)
- Rules
- IACS UR W25 · EN 755-6
Why marine hex bar is made in 5086 and 5059
A hexagonal section gives wrench flats and a ready-made shape for nuts, unions, standoffs and through-deck fittings. Turning those parts from a marine 5xxx alloy keeps them galvanically compatible with an aluminium hull and lets them be welded in place.
5086 hex bar is the everyday option. With about 4 % magnesium it resists seawater very well, welds with ER5356 or ER5183 and machines adequately. Its extruded H112 minimum yield of 95 MPa is enough for most low-pressure couplings, cleat bodies and spacer nuts.
5059 hex bar serves the high-strength end of the market. Its zinc and zirconium additions and 5 – 6 % magnesium give an extruded minimum yield of 200 MPa, so a 5059 boss or nut can be smaller or carry more load than a 5086 part of the same size. It is chosen for fittings on 5059-plated fast craft and naval vessels, and is generally extruded to order.
5059 and 5086 chemical composition
| Element (wt %) | 5059 | 5086 |
|---|---|---|
| Silicon (Si) | 0.45 | 0.40 |
| Iron (Fe) | 0.50 | 0.50 |
| Copper (Cu) | 0.25 | 0.10 |
| Manganese (Mn) | 0.6 – 1.2 | 0.20 – 0.7 |
| Magnesium (Mg) | 5.0 – 6.0 | 3.5 – 4.5 |
| Chromium (Cr) | 0.25 | 0.05 – 0.25 |
| Zinc (Zn) | 0.40 – 0.90 | 0.25 |
| Titanium (Ti) | 0.20 | 0.15 |
| Zirconium (Zr) | 0.05 – 0.25 | — |
| Others, each / total | 0.05 / 0.15 | 0.05 / 0.15 |
| Aluminium (Al) | Remainder | Remainder |
Single figures are maximums. Limits as listed in IACS UR W25 and the Aluminum Association registrations.
Minimum mechanical properties of extruded hex bar
| Alloy | Temper | Yield Rp0.2 min (MPa) | Tensile Rm (MPa) | Elongation A50 / A5 min (%) |
|---|---|---|---|---|
| 5086 | O | 95 | 240 – 315 | 14 / 12 |
| 5086 | H111 | 145 | 250 | 12 / 10 |
| 5086 | H112 | 95 | 240 | 12 / 10 |
| 5059 | H112 | 200 | 330 | — / 10 |
IACS UR W25 Rev.4 Table 3 for extruded products 3 – 50 mm; 5086 values match ASTM B221. For hex bar the thickness is taken as the across-flats dimension.
Physical properties (approximate)
- Density
- 5086: 2.66 g/cm³ · 5059: about 2.65 g/cm³
- Modulus of elasticity
- about 71 GPa
- Thermal expansion
- about 23.8 µm/m·°C
Standards and equivalents
| Standard | Scope |
|---|---|
| IACS UR W25 and class rules | Extruded 5059 and 5086 (and 5083, 5383) for hull and marine structure |
| ASTM B221 / B221M | Extruded bar, rod and profiles; includes 5086 tempers O, H111 and H112 |
| ASTM B928 / B928M | High-magnesium marine products, including extruded profiles, with corrosion testing |
| EN 755-2 | Mechanical properties of extruded bar, tube and profiles |
| EN 755-3 / -4 / -6 | Dimensions and tolerances of round, square and hexagonal extruded bar |
| EN 573-3 | Chemical composition |
EN 755-6 sets across-flats tolerance, corner radius, straightness, twist and length tolerances for extruded hexagonal bar; ANSI H35.2 applies to ASTM orders. If parts are made on bar-fed lathes, specify the tolerance class and check it on receipt, because extruded hex has wider limits than drawn hex.
| System | 5059 | 5086 |
|---|---|---|
| Aluminum Association / ASTM | 5059 | 5086 |
| UNS | A95059 | A95086 |
| European (EN 573-3) | EN AW-5059 / AlMg5.5MnZnZr | EN AW-5086 / AlMg4 |
| German Werkstoff | — | 3.3545 |
| Japan (JIS) | — | A5086 |
| Marine rules | IACS UR W25, rolled and extruded | IACS UR W25, rolled and extruded |
Hex bar sizes and weights
Supply range
- Across flats
- 5086 in common metric and imperial sizes; 5059 extruded to order
- Length
- 3 m, 6 m or cut lengths
- Tempers
- 5086: O, H111, H112 · 5059: H112
- Documents
- EN 10204 3.1, or class certificate where available
Hex weight per metre = 0.866 × s² × density, with s the across-flats size. At 2.66 g/cm³ that is 0.002304 × s² kg per metre.
| Size (mm) | kg per metre | 3 m bar (kg) | 6 m bar (kg) |
|---|---|---|---|
| 10 | 0.230 | 0.69 | 1.4 |
| 13 | 0.389 | 1.17 | 2.3 |
| 17 | 0.666 | 2.00 | 4.0 |
| 19 | 0.832 | 2.49 | 5.0 |
| 22 | 1.11 | 3.34 | 6.7 |
| 24 | 1.33 | 3.98 | 8.0 |
| 27 | 1.68 | 5.04 | 10.1 |
| 30 | 2.07 | 6.22 | 12.4 |
| 36 | 2.99 | 8.96 | 17.9 |
| 41 | 3.87 | 11.62 | 23.2 |
| 46 | 4.87 | 14.62 | 29.2 |
| 50 | 5.76 | 17.28 | 34.6 |
| 55 | 6.97 | 20.91 | 41.8 |
| 60 | 8.29 | 24.88 | 49.8 |
| 70 | 11.29 | 33.86 | 67.7 |
| 80 | 14.74 | 44.23 | 88.5 |
| 100 | 23.04 | 69.11 | 138.2 |
Machining, threading and welding
Galling
Aluminium threads gall against stainless steel. Use anti-seize compound, nylon-insert nuts or helical thread inserts for repeatedly assembled joints.
Welding
Weld 5059 with ER5183 or a zirconium-bearing filler, and 5086 with ER5356 or ER5183. Never use 4xxx fillers on these alloys.
Corrosion
Both resist seawater uncoated. Isolate from bronze and stainless with sleeves and washers, and seal fasteners passing through the hull.
Applications of 5086 and 5059 hex bar
- Nuts, unions and couplings for low-pressure seawater and drain lines
- Through-deck and through-hull bosses welded into aluminium plating
- Standoffs and spacers for equipment mounting on deck and in machinery spaces
- Cleat, fairlead and bollard components
- High-strength fittings on 5059 hulls, where matching alloys simplify welding
- Aquaculture and offshore hardware exposed to continuous immersion
Hex bar alloy options compared
| Extruded, UR W25 minimum | 5086-H112 | 5083-H112 | 5383-H112 | 5059-H112 |
|---|---|---|---|---|
| Yield strength | 95 MPa | 110 MPa | 190 MPa | 200 MPa |
| Tensile strength | 240 MPa | 270 MPa | 310 MPa | 330 MPa |
| Typical availability | Good | Very good | Limited | To order |
Where neither 5086 nor 5059 is a must, 5083 hex bar offers a good middle ground. For dry, highly stressed fittings, 6082-T6 or 6061-T6 hex is stronger but needs protection in seawater.
How to order
- SpecifyAlloy, temper, across-flats size, length, quantity, standard and class requirement.
- QuoteAvailability or production route, certificates and EXW, FOB, CIF or DAP terms confirmed.
- ShipBars inspected, bundled in wooden cases and shipped with mill or class certificates.
References and standards
- IACS Unified Requirement W25 – Aluminium alloys for hull construction and marine structure
- ASTM B221 – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles and Tubes
- EN 755-2 – Extruded rod/bar, tube and profiles: mechanical properties (with EN 755-3, -4 and -6 for round, square and hexagonal bar tolerances)
- ASTM B928/B928M – High Magnesium Aluminum-Alloy Products for Marine Service and Similar Environments
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
5059 and 5086 aluminium (aluminum) hex bar: FAQ
Is 5086 hex bar good for saltwater fittings?
Yes. 5086 has excellent seawater resistance and is widely used for nuts, couplings and bosses on aluminium boats, provided it is isolated from more noble metals.
What is the yield strength of 5059 hex bar?
Extruded 5059-H112 has a minimum yield of 200 MPa and minimum tensile strength of 330 MPa under IACS UR W25 for sizes up to 50 mm.
How is hex bar size measured?
Across the flats (A/F), the distance between two parallel faces. Weight per metre for 5086 is about 0.002304 × A/F² kg.
Can I use 5086 hex bar with stainless bolts?
Yes, but isolate the metals and use anti-seize, because aluminium threads gall against stainless steel and the pair is galvanically active when wet.
Is 5059 hex bar a stock item?
It is usually extruded to order. 5086 and 5083 hex are more readily available.
Need marine hex bar?
Send alloy, across-flats size, temper and quantity. Metline will reply with availability and a delivered price.
