Marine Grade 5083 Aluminum Supplier — Plate · Sheet · Coil · Strip · Tube · Bar | Tempers O / H111 / H112 / H116 / H321 | ASTM B209 · B928 · EN 485 · EN 573-3 | EN 10204 3.1 + Class Society Certs (ABS · DNV · LR · BV · CCS) | MOQ 500 kg | Quote in 24 h
How to Specify, Weld and Source 5083 Marine Aluminum Correctly
Reviewed by the HXM Aluminum marine alloys team · Last updated: September 2026 · Reading time: 18 minutes
If you specify the wrong aluminum for a hull, you will not find out on the drawing – you will find out in the water, years later, when the plating under a tank starts to exfoliate or a weld heat-affected zone pits through. 5083 exists to prevent exactly that failure mode, which is why it has been the reference alloy for welded marine structures since the 1950s and still accounts for the majority of aluminum tonnage in workboats, fast ferries, yachts and offshore hardware.
This guide is written for the people who actually have to buy and fabricate the material: shipyard estimators, naval architects, boatbuilders and procurement engineers. It covers what 5083 is, how the H116 and H321 marine tempers differ, real property and corrosion data, how it compares with 5052, 5086 and 6061, welding and fabrication rules, classification society requirements, the forms and sizes we roll, and how to specify an order so that what arrives is what you designed.
Quick answer
5083 marine grade aluminum is an aluminum-magnesium alloy containing 4.0-4.9% magnesium (UNS A95083, EN AW-5083). It is the highest-strength weldable aluminum routinely used for boats, and the only 5xxx family with dedicated marine tempers – H116 and H321 per ASTM B928 – which are exfoliation-tested and accepted by ABS, DNV, Lloyd’s Register, BV, CCS, RINA and NK. Typical figures: tensile strength from 305 MPa, yield from 215 MPa, density 2.66 g/cm3, general seawater corrosion rate below 0.02 mm/year, and an indicative FOB price of USD 2,800-4,200 per tonne depending on form, thickness, temper and certification.
The five things that matter most
- Temper is the specification. For anything that touches seawater, buy 5083-H116 or 5083-H321 to ASTM B928 – not H112, which carries no exfoliation guarantee.
- Strength after welding is the real design number. With ER5183 filler a sound weld retains roughly 85-95% of base-metal strength, and no post-weld heat treatment is used or needed.
- Weight is the commercial argument. At 2.66 g/cm3 against 7.85 g/cm3 for steel, an aluminum structure is 45-55% lighter at equal stiffness, which translates into speed, payload, fuel burn and stability.
- Corrosion is a design problem, not a material problem. General seawater attack is negligible; pitting, crevice and galvanic attack around stagnant pockets and dissimilar-metal joints are what actually sink projects.
- Paperwork protects the buyer. Insist on EN 10204 3.1 mill certificates, class society approval where the vessel is classed, and thickness/UT verification on thick plate.
What Is 5083 Marine Grade Aluminum?
5083 is a non-heat-treatable aluminum-magnesium-manganese alloy. Its strengthening comes from two things: solid-solution strengthening by 4.0-4.9% magnesium, and strain hardening applied during rolling. There is no precipitation-hardening treatment, which is precisely why the alloy is so weldable and why it keeps its toughness in service – and why 5083 delivers the highest strength of any aluminum alloy that can still be welded without a loss of corrosion resistance.
The practical consequence for a shipyard is that 5083 sits in a sweet spot no other common alloy occupies. 6061-T6 is stronger in the unwelded condition but loses roughly half its strength in the weld heat-affected zone and pits in seawater because of its copper content. 5052 is more formable and cheaper but roughly 10-25% weaker at yield. 5086 is a close relative with slightly less magnesium. For welded structure in a chloride environment, 5083 remains the default, and it has the longest service record of any marine aluminum.
“Marine grade” is not a formal material grade – it is shorthand for 5083 supplied in the marine tempers H116 or H321 under ASTM B928, with exfoliation testing and documented properties. When a specification says “5083 marine grade”, that is what it should mean.
| Designation system | 5083 as written |
|---|---|
| UNS number (USA) | A95083 |
| EN / ISO designation | EN AW-5083 · Al Mg4.5Mn0.7 |
| European material number | 3.3547 (EN 573-3) |
| Chinese standard | 5083 per GB/T 3190, plate per GB/T 3880 |
| Alloy family | 5xxx (Al-Mg), non-heat-treatable |
| Principal alloying element | Magnesium, 4.0-4.9% |
| Common tempers | O, H111, H112, H116, H321 |
| Marine tempers | H116, H321 (ASTM B928, exfoliation tested) |
| Typical product forms | Plate, sheet, coil, strip, tube, bar, rod, wire, extrusions |
Designations used in purchase orders and drawings. Quoting the UNS or EN number in your PO removes any ambiguity about alloy and temper.
5083 Aluminum Chemical Composition
The composition window below is the one that matters commercially: it is the range permitted by ASTM B209 / B928 and EN 573-3 for 5083. Two limits in this table do most of the work in marine service. Magnesium sets the strength and the corrosion resistance. Iron and silicon kept low, plus the addition of chromium and manganese, control the size and type of intermetallic particles that act as pitting initiation sites – which is why a mill that pushes iron towards the upper limit to save cost is degrading exactly the property you are paying for.
| Element | Content (% by weight) | Role in 5083 |
|---|---|---|
| Magnesium (Mg) | 4.0 – 4.9 | Solid-solution strengthening; passive-film quality |
| Manganese (Mn) | 0.40 – 1.00 | Recrystallisation control; dispersoid formation |
| Chromium (Cr) | 0.05 – 0.25 | Grain structure; resistance to stress-corrosion cracking |
| Iron (Fe) | 0.40 max | Impurity – kept low to limit cathodic particles |
| Silicon (Si) | 0.40 max | Impurity – low Si+Fe improves corrosion behaviour |
| Copper (Cu) | 0.10 max | Strictly limited – copper drives pitting in seawater |
| Zinc (Zn) | 0.25 max | Impurity |
| Titanium (Ti) | 0.15 max | Grain refinement |
| Others, each | 0.05 max (total 0.15 max) | Residual elements |
| Aluminium (Al) | Remainder | Matrix |
Composition limits to ASTM B209 / B928 and EN 573-3. Copper is the element to police hardest on a marine order: 0.10% is already generous by marine standards, and any supplier substituting a copper-bearing 5xxx alloy will show up in the mill certificate.
Read the mill certificate against this table before the plate is cut. A 5083 certificate that shows magnesium below 4.0% is out of specification, and one that shows iron or silicon at the limit should trigger a conversation about corrosion performance rather than a discount.
Physical Properties of 5083 Aluminum
These are the numbers design engineers need for weight, thermal and stiffness calculations. Note the thermal expansion figure: 5083 expands roughly twice as much as steel for the same temperature change, which is the origin of most welding distortion problems and of the design rules for expansion gaps in long deck houses and railings.
| Property | Value | Notes for designers |
|---|---|---|
| Density | 2.66 g/cm3 | vs 7.85 g/cm3 for steel – 66% lighter by volume |
| Elastic modulus | 70 – 71 GPa | About one third of steel; compensate in stiffness-driven designs |
| Melting range | 570 – 640 degrees C | Solidus 570 C, liquidus 638 C |
| Thermal conductivity | 117 – 120 W/m.K | 5 times steel – excellent heat spreading, fast cooling in welds |
| Thermal expansion | 23.8 x 10^-6 /K (20-100 C) | Twice steel; drives distortion and expansion-joint design |
| Specific heat | 900 J/kg.K | Relevant to LNG and heat-exchanger duty |
| Electrical conductivity | 28 – 29% IACS | Non-critical for most marine structures |
| Relative permeability | ~1.0 (non-magnetic) | Suitable for survey and research vessels |
| Service temperature | Up to ~65 C continuous | Above this, sensitisation risk in welded marine structures |
| Cryogenic service | Excellent to -196 C | Standard material for LNG containment |
Typical values for 5083 across tempers; confirm exact figures for the temper and thickness you are ordering.
Two of these numbers decide real design choices. The low modulus means an aluminum panel deflects about three times as much as a steel panel of identical dimensions and thickness at the same load – which is why marine aluminum structures use stiffener spacing and section depth rather than raw plate thickness to control deflection. The high thermal expansion means welding sequence planning is not optional; it is the difference between a fair hull and a fair set of filler.
Mechanical Properties of 5083 by Temper
This is the table to take into a structural calculation. Values are minimum specified properties for plate in the 3-12.5 mm range to ASTM B209 / B928 and EN 485-2; strength falls slightly as thickness increases, so always confirm the exact thickness class for a critical lift or a highly stressed panel. Typical (as-produced) values run a few percent above the minimums shown.
| Temper | Tensile strength Rm (MPa) | Yield strength Rp0.2 (MPa) | Elongation A50 (%) | Hardness (HB) | Typical role |
|---|---|---|---|---|---|
| O | 275 – 345 | 125 – 145 | 16 – 20 | ~75 | Fully annealed; severe forming, cryogenic tanks |
| H111 | 275 – 345 | 145 – 165 | 14 – 18 | ~80 | Lightly strain-hardened; general fabrication |
| H112 | 280 – 305 | 125 – 145 | 12 – 16 | ~85 | Hot-rolled plate; non-critical, no exfoliation guarantee |
| H116 | 305 – 345 | 215 – 250 | 10 – 12 | ~90 | Marine structure, hull plating, seawater immersion |
| H321 | 305 – 345 | 215 – 250 | 10 – 12 | ~90 | Marine structure, thermally stabilised, class approved |
Minimum specified values, plate 3-12.5 mm. Thicker plate is tested to lower minimums; ask us for the thickness-specific data sheet when the calculation is marginal.
The jump from H112 to H116/H321 is the one that matters: roughly 70 MPa of extra yield strength, which in a stiffness-limited panel often allows one thickness step down – and that step saves both weight and money. It is also accompanied by the exfoliation-resistance requirement, the property that keeps the alloy from delaminating in a warm, wet, chloride-rich environment.
For comparative data across other alloys and tempers, see our aluminum mechanical properties chart.
H116 vs H321: Choosing the Right Marine Temper
These two tempers confuse more buyers than any other aspect of 5083, and they are frequently specified interchangeably. They are both strain-hardened marine tempers covered by ASTM B928, and their minimum mechanical properties are the same – but they get there slightly differently, and each has become the house standard in different parts of the world.
| 5083-H116 | 5083-H321 | |
|---|---|---|
| Covering standard | ASTM B928 | ASTM B928 |
| Production route | Strain-hardened, no stabilisation | Strain-hardened then thermally stabilised |
| Exfoliation resistance | Required – ASTM G66 tested | Required – ASTM G66 tested |
| Microstructure | More anisotropic through thickness | More uniform, better through-thickness consistency |
| Regional preference | North America; US hull specs | Europe, classification-society practice, Asia |
| Typical minimum Rm / Rp0.2 | 305 / 215 MPa | 305 / 215 MPa |
| Where it is used | Hull plating, decks, superstructure | Hull plating, decks, tanks, classed vessels |
How to decide in practice:
- If a classification society, a naval architect or an end user has named a temper on the drawing, buy that temper. Do not substitute.
- If the specification is open, choose H116 for North-American projects and for hull bottoms and tanks where exfoliation resistance is the governing requirement.
- Choose H321 when the plate will be heavily formed or when the buyer’s standard is EN-based or class-driven; the thermal stabilisation gives slightly better through-thickness uniformity.
- Never accept H112 for seawater-immersed structure merely because it is cheaper or in stock – it carries no exfoliation guarantee and is not a marine temper.
Why the distinction exists at all. Magnesium in aluminum is only fully in solution because of rapid cooling after hot rolling. Over months at ambient temperature, or within hours at temperatures above roughly 65 degrees C, the magnesium-rich Mg2Al3 phase can precipitate continuously along grain boundaries – the sensitisation mechanism. Sensitised 5083 loses its intergranular corrosion resistance and can exfoliate in a marine atmosphere. Both H116 and H321 are defined to guarantee resistance to that process, which is why they are the only tempers we recommend for immersed marine service.
Why 5083 Became the Marine Standard
1. Seawater corrosion resistance that does not depend on coating
Aluminum protects itself. In oxygenated water the surface instantly forms a tenacious oxide layer roughly 3-5 nm thick which reforms within milliseconds if damaged. In marine environments 5xxx alloys with high magnesium form a particularly stable passive film, and general corrosion rates stay below 0.02 mm per year in flowing seawater. Compare that with the 0.1-0.5 mm per year typical of bare structural steel: over a 25-year life the aluminum hull loses a fraction of a millimetre while the steel structure would need re-blasting and recoating several times, or sacrificial thickness that weighs more than the aluminum it replaces. Our aluminum corrosion resistance guide covers the mechanisms in detail.
2. The best strength-to-weight ratio of any weldable marine aluminum
At 2.66 g/cm3 with a yield strength from 215 MPa in the marine tempers, 5083 delivers a specific yield strength that steel cannot match at comparable fabrication cost. In practice a welded 5083 hull structure weighs 45-55% less than the steel equivalent. For a planing boat that weight comes straight out of the required installed power; for a displacement vessel it converts into payload and fuel economy; for any vessel it lowers the centre of gravity and improves stability. We’ve compared the underlying numbers with steel in aluminum vs steel for engineers and buyers.
3. Weldability that survives the heat-affected zone
Because 5083 is not heat-treatable, welding does not destroy a strengthening precipitate. The heat-affected zone softens by strain-hardening recovery only, and a joint made with ER5183 filler retains roughly 85-95% of base-metal strength as-welded. No pre-heat, no post-weld heat treatment, no quench – a yard with ordinary MIG equipment and trained welders can build the structure. The practical rules are in our aluminum welding guide and in the welding section below.
4. Classification society approval and cryogenic toughness
5083-H116 and H321 are approved by ABS, DNV, Lloyd’s Register, BV, CCS, RINA and NK for hull, deck and tank structure, and 5083-O is the long-established material for LNG containment because it stays ductile down to -196 degrees C. No other aluminum alloy combines that approval base, that service history and that low-temperature performance.
5083 Aluminum in Seawater: What Actually Happens
The picture above is a test panel after extended exposure, and it is deliberately included because it shows what 5083 does not do. There is no uniform thinning, no red rust, no perforation – the surface has localised pitting where stagnant water, scale or deposits broke the passive film. Corrosion of aluminum in the sea is a localised, design-driven phenomenon.
| Corrosion mode | Typical severity in marine service | How to control it |
|---|---|---|
| General (uniform) attack | < 0.02 mm/year in flowing seawater | Allow 0.3-0.5 mm per side for 20+ year life |
| Pitting | Localised; worst in stagnant, low-oxygen water | Design for drainage; avoid pockets, bilge traps, scale |
| Crevice corrosion | Under gaskets, brackets, weld spatter, marine growth | Seal joints, use bedding compound, avoid overlaps |
| Galvanic corrosion | Severe if coupled to bronze, stainless or steel | Insulating kits at every dissimilar-metal joint |
| Erosion-corrosion | Accelerates above roughly 2.4 m/s flow | Size piping for velocity; avoid sharp bends at high flow |
| Sensitisation / exfoliation | Above ~65 C in welded, sensitised zones | Specify H116/H321; keep service temperature down |
| Intergranular SCC | Rare – requires sensitisation plus tensile stress | Marine temper + avoid sustained hot wet service |
| Alkali attack | If pH exceeds about 9 (over-protection) | Correctly sized cathodic protection, not over-protection |
The design rules that follow from the table:
- Let water drain. Every horizontal surface should have a path to the bilge; every enclosed volume should be ventilated. Stagnant seawater is the single largest cause of aluminum hull corrosion.
- Isolate dissimilar metals electrically. Bronze through-hulls, stainless fasteners, steel engine beds and copper piping must be separated from 5083 with insulating gaskets, sleeves and washers, or bonded through a properly engineered cathodic protection system.
- Keep the paint system intact where you use one, and never apply copper-based antifouling directly to bare aluminum – use a barrier coat.
- Respect the velocity limit of about 2.4 m/s in continuous seawater service. Above that, erosion removes the passive film faster than it can reform.
- Take a hull potential reading at commissioning and annually. It is the cheapest early-warning system available for a boat that sits in a marina with other vessels.
Where the vessel mixes aluminum with steel or bronze in piping systems, the joint-by-joint rules are set out in our guide to aluminum tube for marine piping systems.
5083 vs 5052 vs 5086 vs 6061 for Marine Use
This is the comparison buyers ask for most often, and the honest answer is that three of these four alloys are genuinely good in the marine environment while one is a compromise that must be managed. The table uses the marine or most common temper for each alloy.
| Property | 5083-H116 | 5086-H116 | 5052-H32 | 6061-T6 |
|---|---|---|---|---|
| Magnesium content (%) | 4.0 – 4.9 | 3.5 – 4.5 | 2.2 – 2.8 | 0.8 – 1.2 |
| Density (g/cm3) | 2.66 | 2.66 | 2.68 | 2.70 |
| Tensile strength, min (MPa) | 305 | 275 | 228 | 290 |
| Yield strength, min (MPa) | 215 | 193 | 193 | 240 |
| Weld strength retention | Excellent (85-95%) | Very good | Good | Poor (~50% in HAZ) |
| Seawater corrosion | Excellent | Excellent | Very good | Moderate – pitting risk |
| Exfoliation testing (ASTM B928) | Yes (H116/H321) | Yes (H116) | No | No |
| Class society approval for hulls | Yes – primary alloy | Yes | Limited to non-structural | Not for immersed structure |
| Formability | Moderate | Good | Excellent | Limited |
| Machinability | Moderate | Moderate | Good | Excellent |
| Relative cost index | 1.00 | 0.95 – 1.00 | 0.80 – 0.90 | 0.85 – 0.95 |
| Best marine role | Hulls, decks, structure | Hulls, tanks, fabrications | Tanks, interiors, panels, ducting | Coated fittings, masts, non-immersed parts |
Minimum properties to ASTM B209 / B928 / EN 485-2; cost indices are indicative only and move with the LME and magnesium premium.
How to choose, in one paragraph. Specify 5083-H116 or H321 for anything that is welded, load-bearing and immersed: hull plating, frames, decks, bulkheads, keels, rudder structures, tank structure, offshore brackets. Use 5086 where you want almost the same performance with slightly better formability and often a keener price for the same role. Use 5052-H32/H34 for non-structural and lightly loaded parts – fuel and water tanks, consoles, interiors, ducting, superstructure skins, pontoon shells – where formability and finish matter more than yield strength. Reserve 6061-T6 for coated, non-immersed components: masts, spreaders, fittings, brackets and machined parts. We walk part-by-part through the 5052/5083 decision in the 5052 vs 5083 buyer guide for marine applications, and cover the family logic in 3 series vs 5 series aluminum.
Welding 5083 Marine Aluminum: Fillers and Parameters
Welding is where a good specification is either delivered or lost. 5083 welds cleanly, but aluminum is unforgiving of contamination and poor preparation – it has a high thermal conductivity (heat leaves the weld pool five times faster than in steel), a refractory oxide layer melting at over 2,000 degrees C, and no colour change to tell the welder when it is ready. Train for it, prepare for it, and use the right filler.
| Filler (AWS A5.10) | Typical use on 5083 | Notes |
|---|---|---|
| ER5183 | First choice for hulls, decks, structural joints | Best as-welded strength match; use for all critical joints |
| ER5356 | General fabrication, thinner sections, railings, interiors | Most available and best feeding; ~5% lower strength than 5183 |
| ER5556 | Thick plate, highly stressed joints, when 5183 is unavailable | Higher alloy content; excellent strength, slightly less ductile |
| ER4043 | Not for structural marine joints | Al-Si filler; lower strength and ductility – avoid in seawater structure |
| Parameter | MIG (GMAW), plate 6-20 mm | TIG (GTAW), plate 3-8 mm |
|---|---|---|
| Current / polarity | DCEP, 180 – 280 A | AC with balance control, 100 – 220 A |
| Voltage | 24 – 28 V | 12 – 18 V (arc voltage) |
| Wire / filler diameter | 1.2 mm (1.6 mm above 15 mm) | 2.4 – 4.0 mm |
| Shielding gas | 100% argon, 18 – 22 L/min | 100% argon, 10 – 15 L/min |
| Joint preparation | V-groove 60-70 degrees included, U-groove for thick plate | Square edge to 4 mm, V-groove above |
| Preheat | None above 10 C ambient; max 100 C if used | None above 10 C ambient |
| Interpass temperature | Keep below 150 C | Keep below 150 C |
| Post-weld heat treatment | Not required and not used | Not required and not used |
Starting parameters for reference only. Qualified welding procedures (WPS/PQR) to your class society rules govern production welding.
The five rules that decide weld quality on 5083:
- Dedicate stainless-steel brushes, burrs and cutting discs to aluminum only. A tool that has touched carbon steel embeds iron particles that become pitting sites.
- Remove the oxide and any moisture or oil within 30 minutes of welding – aluminum re-oxidises quickly, and a hot, humid shipyard is the worst case.
- Fit up accurately and use balanced, back-step sequences. With twice the thermal expansion of steel, 5083 distortion is managed by sequencing, tacking and restraint – not by force afterwards.
- Consider back-purge or a ceramic backing tape on full-penetration joints; a sugared root is a corrosion initiation site.
- Record the filler batch and welder qualification with the joint. For classed vessels, this documentation is audited.
Method selection, machine settings and troubleshooting are covered in more depth in our aluminum welding guide: methods and filler metals.
Forming, Cutting and Machining 5083
| Operation | Practical guidance for 5083 |
|---|---|
| Cold bending (O / H111) | Minimum inside radius about 0.5-1t; severe forming is best done in the annealed temper and left as-formed |
| Cold bending (H116 / H321) | Minimum inside radius about 2.5-3t transverse to rolling direction; more if bending along the rolling direction |
| Springback | High – plan 15-30% overbend, or use a press brake with compensation; test on an offcut first |
| Shearing / guillotining | Clean edges on tempers up to H116; keep blades sharp and set clearance to 6-8% of thickness |
| Plasma / waterjet cutting | Both work well; waterjet gives the cleanest edge with no heat-affected zone on thick plate |
| Machining | Free-cutting compared with steel but gummy – use high rake, generous chip clearance and flood coolant |
| Rolling / curving | Roll plate transverse to the rolling direction wherever possible; anneal only if the radius demands it |
| Surface preparation | Do not use steel wire brushes or steel grit; use stainless or aluminum-oxide media only |
Practical shop-floor limits. Formability depends on thickness, temper and bend direction, so confirm on a sample before committing a full plate.
Aluminum behaves differently enough from steel that crews used to steel plate need specific training: it cuts faster, springs back more, distorts more and contaminates easily. Our aluminum bending and forming guide, machining and CNC guide and how to cut aluminum guide cover the shop-floor detail; if you would rather hand the fabrication over, we offer aluminum processing services including cut-to-size, slitting, shearing and custom fabrication support.
Where 5083 Marine Grade Aluminum Is Used
Hull plating, frames and superstructure
The largest single application. 5083-H116/H321 plate forms bottoms, sides, transoms, decks, bulkheads, frames and stiffeners on everything from 4 m tinnies to 60 m catamaran ferries and patrol boats. The combination of weldability, toughness after welding and seawater corrosion resistance is what makes an all-welded aluminum hull practical. Plating is usually 4-8 mm for workboats, up to 12-25 mm in the slamming and keel zones of larger fast craft.
Liquefied gas and cryogenic tanks
5083-O is the classic material for LNG containment and for cryogenic road tankers and storage because it retains ductility and toughness down to -196 degrees C, where ferritic steels would fail in a brittle mode. It is also widely used for LNG-fuelled vessel bunker tanks and for liquefied gas carrier structures.
Offshore structures, helidecks and access systems
Weighing roughly one third of the steel equivalent, aluminum helidecks and platform access structures reduce the topside load the jacket has to carry, which lowers long-term structural cost. Supporting structure and brackets are typically 5083 or 5086 in marine tempers, with extrusion profiles used for handrails, ladder systems and walkways.
Marine piping, tanks and hydraulic systems
Seawater cooling lines, bilge and ballast systems, fuel tanks, fresh-water tanks, exhaust downstream sections and hydraulic return lines are commonly 5083 tube, pipe and plate. Weight saving high in the hull improves stability, and aluminum lines are immune to the internal rust scale that chronically clogs steel fuel systems. See aluminum tube for marine piping systems and our range of 5083 aluminum tubes.
Marine hardware, fittings and machinery components
Cleats, bollards, brackets, mounts, hatch frames, rudder components, shaft brackets, davits and davit bases – often 5083 bar and rod machined to shape, or 5083-H321 round bar for higher-strength components. Because 5083 is non-magnetic, it is also preferred on survey and research vessels where the hull must not disturb magnetometers. For joining and welding consumables, see 5083 aluminum welding wire.
Standards, Certificates and Class Society Approval
For a classed vessel or a defence or ferry project, the paperwork is as important as the metal. This is the reference grid our marine team works to when a customer sends a specification – and the checklist we recommend any buyer uses to audit a quotation.
| Item | Standard / requirement |
|---|---|
| Plate and sheet | ASTM B209, ASTM B928 (marine tempers), EN 485-2/-4, GB/T 3880 |
| Tube and pipe | ASTM B241, EN 755,-2/-9 (extruded), EN 754 (drawn) |
| Bar, rod and profiles | ASTM B221, EN 755-1/-3/-9 |
| Alloy designation | EN 573-3, UNS A95083 |
| Marine tempers | H116 and H321 to ASTM B928 |
| Exfoliation resistance | ASTM G66 test report available on request |
| Weld filler | AWS A5.10 (ER5183 / ER5356 / ER5556) |
| Classification societies | ABS, DNV, Lloyd’s Register, BV, CCS, RINA, NK |
| Mill test certificate | EN 10204 3.1 (standard) / 3.2 (witnessed, on request) |
| Third-party inspection | SGS, BV, TUV, Intertek – pre-shipment |
| Non-destructive testing | Ultrasonic testing for thick plate; PMI on request |
| Welding procedure | WPS/PQR qualified to class rules for production welding |
One practical warning: a mill certificate for 5083 to ASTM B209 is not the same document as one to ASTM B928. B928 is the marine specification that adds the exfoliation-resistance requirement for H116 and H321. If your vessel is classed or insured as a commercial craft, ask for the B928 route explicitly, and check that the temper on the certificate matches the temper on the drawing.
5083 Forms, Tempers and Sizes We Roll and Stock
HXM Aluminum supplies 5083 marine grade aluminum in the full range of wrought forms, so that a yard can buy hull plate, tank coil, internal piping, machined fittings and welding wire from one supplier on one set of certificates – which simplifies incoming inspection considerably.
| Form | Tempers | Typical size range | Standard |
|---|---|---|---|
| Plate | O, H111, H112, H116, H321 | Thickness 6 – 150 mm; width to 2,600 mm; length to 12,000 mm | ASTM B209 / B928, EN 485 |
| Sheet | O, H111, H116 | Thickness 0.5 – 6.0 mm | ASTM B209, EN 485 |
| Coil | O, H111, H112 | Thickness 0.2 – 6.0 mm; width to 1,600 mm | ASTM B209, EN 485 |
| Strip | O, H111, H112 | Thickness 0.2 – 4.0 mm, slit to width | ASTM B209, EN 485 |
| Tube and pipe | O, H112, H116, H321 | OD 10 – 300 mm; wall 1 – 20 mm | ASTM B241, EN 755 |
| Bar and rod | H112, H116, H321 | Diameter 10 – 400 mm; square, hex and flat available | ASTM B221, EN 755 |
| Wire | H14, H18, O | For welding consumables and fabrication | AWS A5.10 / ASTM B316 |
| Profiles / extrusions | H112, custom | Standard and custom dies on volume projects | ASTM B221 |
Indicative ranges – exact availability depends on width and temper. Cut-to-size, PVC film, edge chamfering and custom lengths available on all forms.
Buy the form that matches the part. Plate for structure, coil and strip for tank shells, ducting and long runs where a continuous length reduces welded joints, tube for fluid systems, bar and rod for machined hardware. Fabricating a 6 m tank from plate instead of coil can add more cost in welding and inspection than the coil premium. Jump to the product pages for 5083 sheets and plates, 5083 coils, 5083 strips, 5083 tubes, 5083 bars and 5083-H321 round bar.
How to Specify and Order 5083 Marine Aluminum
Most disputes between yards and suppliers trace back to a purchase order that left something to interpretation. A complete marine PO for 5083 contains nine items. Use this as a checklist before you send the enquiry – it is also exactly the information our team needs to quote accurately and quickly.
| # | What to state | Why it matters |
|---|---|---|
| 1 | Alloy and temper: 5083-H116 or 5083-H321 (or the service condition, if you want a recommendation) | Temper defines corrosion performance and strength – the single most common omission |
| 2 | Product form and dimensions, with tolerance class | Plate and coil tolerances differ; nominal thickness is not enough for critical panels |
| 3 | Quantity per size, plus total | Determines whether stock or a mill run is the better route |
| 4 | Standard: ASTM B209 / B928, EN 485, GB/T 3880 | B928 is the marine route with exfoliation testing |
| 5 | Certification: EN 10204 3.1 or 3.2; class society approval | Needed for classification, insurance and warranty |
| 6 | Testing: UT, PMI, ASTM G66, third-party witness | Thick plate and classed vessels frequently require it |
| 7 | Surface condition: mill finish, PVC film, protective coating | Prevents transit scratching and rework at the yard |
| 8 | Special requirements: cut-to-size, edge condition, marking, traceability | Cutting and marking at the mill is cheaper than at the yard |
| 9 | Destination port and Incoterm (FOB, CIF, DDP) | Drives packing standard and the freight element of the price |
Send an enquiry with those nine items and you will normally receive a technically reviewed quotation – including any recommendation to change temper or thickness that we think will improve the outcome – within one working day.
Quality Control, Documentation and Export Packing
Buying marine aluminum is buying evidence as much as metal. Before any plate is cut, our quality team verifies that the heat lot matches the certificate, that composition and mechanical properties fall inside the specification window, and that dimensions and flatness meet the tolerance class on the order. What ships with the goods:
- EN 10204 3.1 mill test certificate per heat lot – composition, tensile, yield, elongation and dimensions.
- EN 10204 3.2 with an independent witness where the end user or class society requires it.
- Class society certificates from ABS, DNV, LR, BV, CCS or RINA on approved grades and tempers.
- ASTM G66 exfoliation test reports for H116 / H321 marine tempers on request.
- Ultrasonic testing for thick plate and for critical structural applications.
- PMI and dimensional reports, plus material traceability marking on every piece where the specification demands it.
- Third-party pre-shipment inspection by SGS, BV, TUV or Intertek at our works, arranged at your request.
Packing is specified per order. Typical marine export packing uses wooden pallets or crates with VCI paper and plastic film wrapping, steel or PET strapping, edge protection and internal desiccant where the shipment will pass through humid climates. Plate is stacked interleaved with protective film and can be supplied with PVC film on one or both faces for yards that want to weld without re-cleaning. Every bundle is marked with alloy, temper, size, heat lot, quantity and the purchase order number.
Our quality testing services page sets out the full inspection capability, and we are happy to work to a customer-supplied ITP.
Six Costly Mistakes When Buying 5083 for Marine Projects
Every one of these has cost a yard real money and schedule. They are listed in the order we see them most often.
| Mistake | What it costs | What to do instead |
|---|---|---|
| Buying 5083-H112 for immersed structure because it is cheaper or in stock | Exfoliation and intergranular corrosion after a few seasons; possible class non-compliance | Specify H116 or H321 to ASTM B928 for anything in contact with seawater |
| Accepting a quotation with no mill certificate or an unclear heat lot | No traceability, no warranty position, unverifiable properties | Require EN 10204 3.1 as a condition of the PO |
| Specifying 5083 everywhere, including non-structural parts | Paying 15-25% more than necessary and losing formability | Reserve 5083 for load-bearing and immersed structure; use 5052 for tanks, interiors and panels |
| Bolting aluminum directly to bronze, stainless or steel without isolation | Galvanic corrosion concentrated at the joint, often perforating within a few years | Insulating kits, dielectric gaskets and a properly sized cathodic protection system |
| Choosing 4043 filler because it welds more easily | Lower joint strength and ductility in exactly the joints that carry load | Use ER5183 for structural joints, ER5356 for general work; reserve 4043 for non-structural repairs |
| Ordering nominal thickness without a tolerance class | Under-thickness plate that fails the structural calculation | State the tolerance class and, for critical plate, verify thickness and flatness on receipt |
How 5083 Marine Aluminum Is Priced
We do not publish a fixed price list for 5083, and no serious mill does – the number depends on factors that change weekly and on the specification you actually need. What we can do is explain precisely what drives the price, so you can read a quotation intelligently and compare like with like.
| Cost driver | Effect on price | How to optimise it |
|---|---|---|
| LME aluminum base | Dominant element, moves daily | Lock the base with your supplier for project quantities |
| Magnesium alloying premium | Higher for 5083 than for 5052 or 3003 | Non-negotiable – it is the alloy’s value |
| Thickness and width | Thicker and wider plate costs more per tonne; non-standard widths add rolling cost | Design to available standard widths where possible |
| Temper | H116 / H321 cost more than H112 or O due to extra processing and testing | Use marine tempers only where the service requires them |
| Quantity | Larger heats reduce per-tonne cost; small lots carry setup cost | Consolidate sizes; 500 kg MOQ applies for stock items |
| Certification | 3.1 standard; 3.2, class society and third-party inspection add cost | Specify only the certification the project genuinely needs |
| Surface and processing | PVC film, cut-to-size, chamfering, slitting add value but remove downstream work | Mill processing is usually cheaper than yard processing |
| Freight and Incoterm | FOB vs CIF vs DDP changes the landed figure substantially | Compare on a landed-cost basis, not ex-works |
Indicative FOB China range for 5083-H116/H321 plate: about USD 2,800-4,200 per tonne depending on form, thickness, temper, quantity and certification. Coil, strip and tube price differently.
Two habits make procurement easier. First, compare suppliers on a landed cost per finished part, not a price per tonne – cheap plate that needs re-cutting, or that arrives with a 0.3 mm negative thickness tolerance, is not cheap. Second, tell your supplier what the plate will do. A supplier who knows the material is going into a 38 m catamaran ferry’s wet deck will quote H321 with the right certificates first time, rather than H112 that has to be returned. Market context and current ranges are in our 2026 aluminum price trends and factory-direct quote guide.
Why Source 5083 Marine Aluminum from HXM
HXM Aluminum is a Chinese aluminum mill and supplier serving shipyards, boatbuilders and marine equipment manufacturers in more than 60 countries. Our marine customers typically value four things, and we have built the service around them.
| What you need | What we provide |
|---|---|
| Correct alloy and temper, every time | 5083 in O / H111 / H112 / H116 / H321, with the temper verified on the certificate before dispatch |
| Documentation that satisfies the class society | EN 10204 3.1 as standard; 3.2, class certificates (ABS / DNV / LR / BV / CCS / RINA) and third-party inspection on request |
| Material in the size the design needs | Cut-to-size plate, slit coil and strip, chamfered and end-capped tube, custom lengths – processed at the mill, not at your yard |
| A fast, technically competent answer | Quotations reviewed by people who understand marine service, returned within 24 hours with our recommendation on temper and thickness |
| Manageable entry quantities | MOQ from 500 kg on stock items, so repair yards and prototype builders are not excluded |
| Deliveries that survive the voyage | Sea-worthy export packing with VCI protection, marking and traceability to the heat lot |
If you are at the specification stage and have not yet fixed a temper or thickness, send us the service condition – vessel type, area of structure, welding method and required life – and we will come back with a recommended specification and an indicative price. There is no charge for that engineering review, and it has saved a number of customers from an expensive specification error. See also our 5000 series aluminum range and the full aluminum sheet and plate catalogue.
Frequently Asked Questions
What does "5083 marine grade aluminum" actually mean?
It means the alloy is produced and tested to a marine specification rather than merely being made of a 5xxx alloy. 5083 is an Al-Mg alloy with 4.0-4.9% magnesium (UNS A95083, EN AW-5083 / Al Mg4.5Mn0.7). The marine designation refers to tempers H116 or H321 per ASTM B928, which must pass exfoliation-corrosion testing and retain mechanical properties after long-term seawater exposure. A supplier quoting “5083-H112” for a hull bottom is selling an untested, non-marine temper.
What is the difference between H116 and H321 temper?
Both are special marine tempers developed for seawater service and both are covered by ASTM B928. H116 is strain-hardened and must demonstrate resistance to exfoliation corrosion (ASTM G66) – it is the classic North-American hull specification. H321 is strain-hardened and then thermally stabilised, which produces a more uniform microstructure; it is widely referenced in European and classification-society practice. Minimum properties are effectively the same: tensile strength from 305 MPa and yield strength from 215 MPa. In practice, choose whichever your class society or end user names – we supply both and, on request, can run ASTM G66 exfoliation testing.
5083 or 5052 - which should I specify for my boat?
Use 5083 for structure: hull plating, decks, bulkheads, frames, brackets and anything welded that carries load. Its yield strength (from 215 MPa in H116) is roughly 10-25% higher than 5052 and it holds strength better after welding. Use 5052-H32/H34 for non-structural and lightly loaded parts – fuel tanks, lockers, ducting, interior furniture, panels, pontoon skins – where formability and cost matter more. 5052 is also the better choice for bright anodised or painted superstructure parts because it takes finish more uniformly. Our buyer’s guide to 5052 vs 5083 for marine work walks through the decision part by part.
Can 5083 be used in fresh water and on inland vessels?
Yes, and it is often over-specified there. In fresh water the corrosion risk is lower, so 5052, 5083-H111 or even 6061-T6 (coated) become viable for many components. The usual reason yards still choose 5083 for river craft and workboats is the structural advantage – fatigue strength, weld strength and impact toughness – rather than corrosion. If the vessel may later operate in brackish or coastal water, specify the marine temper from the start; retrofitting is not possible.
What is the maximum service temperature for 5083?
Continuous service should stay below about 65 degrees C for welded and sensitised structures. Above that, the magnesium-rich phase (Mg2Al3 / beta phase) precipitates along grain boundaries, a phenomenon called sensitisation, and the alloy becomes susceptible to intergranular and stress-corrosion cracking in a marine environment. Short-term excursions are tolerable – exhaust downstream sections and engine-room components are common – but for sustained hot service above 65 degrees C specify 5052 or 6061 instead, and never use 5083 for dry exhaust above roughly 150 degrees C.
Which welding filler metal should be used with 5083?
ER5183 is the first choice for 5083 marine structures because it matches base-metal strength best. ER5356 is the general-purpose alternative – more widely available, slightly lower as-welded strength, excellent feedability. Use ER5556 for thick sections or when maximum joint strength is needed. Avoid ER4043 for structural marine joints: its 5% silicon addition lowers strength and ductility in the weld. Filler selection, gas flow and joint preparation are covered in our aluminum welding guide.
Do I need to heat-treat or stress-relieve after welding 5083?
No. 5083 is a non-heat-treatable alloy; there is no precipitation hardening to restore, so post-weld heat treatment is never used and can actually harm corrosion resistance by over-ageing the microstructure. In the as-welded condition a correctly made 5183 joint retains roughly 85-95% of base-metal strength. Residual stresses are managed by good fit-up, balanced welding sequence, back-step technique and, where needed, mechanical straightening – not by thermal treatment.
How fast does 5083 corrode in seawater?
In clean, flowing seawater the general corrosion rate of 5083 is extremely low – typically less than 0.02 mm per year (often quoted as 0.005-0.02 mm/y), which is why a 5-6 mm hull plate has a 25-year-plus service life. The real risks are not general thinning but: pitting in stagnant, oxygen-depleted pockets; crevice attack under gaskets and scale; erosion at flow velocities above about 2.4 m/s; and galvanic corrosion where the aluminum is coupled to stainless, bronze or carbon steel without isolation. Design for drainage, keep velocities moderate and isolate dissimilar metals.
Can 5083 aluminum be anodized or painted?
Both. Anodising works but the 4.5% magnesium content produces a darker, greyer and less transparent oxide than 5052 or 6061, so 5083 is rarely used where a bright decorative finish is required. For marine service, hard anodising type III on small components is common. Painting is the more typical route: a conversion coating or blast-and-etch, then an epoxy primer and, below the waterline, an antifouling system – note that copper-based antifoulings must never be applied directly to bare aluminum. See our surface finishing guide for the full sequence.
Does 5083 become brittle at low temperature?
No – the opposite. Because 5083 has no body-centred-cubic phase, its ductility is retained down to cryogenic temperatures, with impact toughness remaining high at -196 degrees C (liquid nitrogen). This is exactly why 5083-O plate is the established material for LNG containment and why it is used for liquefied gas tanks, cold-storage structures and cryogenic road tankers. Carbon steel of the same strength would fail in a brittle mode in the same service.
What thickness of 5083 plate should I use for a boat hull?
Thickness is a design decision that belongs to the naval architect, but yard rules of thumb for welded 5083 bottoms are 3-4 mm for boats up to about 6 m, 4-5 mm for 6-9 m, 5-6 mm for 9-14 m, and 6-10 mm for larger workboats, with plating one step thinner above the waterline. Reduce thickness by 0.5-1 mm if the boat is trailered rather than permanently moored, and increase it in the slamming zone forward. Always add a corrosion allowance of 0.3-0.5 mm per side for design lives beyond 20 years, and confirm against class rules for the tonnage you are building.
Is 5083 magnetic? Can I use it near a compass?
5083 is non-magnetic in the practical sense – its relative permeability is close to 1.0, so it does not disturb compasses or magnetometers the way steel does, which is one reason aluminum is preferred for survey vessels, mine-hunters and research craft. Have the hull demagnetised after welding if the yard used magnetic lifting gear, and keep the compass correctly sited as recommended by your navigational equipment supplier.
How do I calculate the weight of a 5083 plate or bar?
Use the density of 5083: 2.66 g/cm3. For millimeters, weight (kg) = length x width x thickness (mm) / 1000 x 2.66. A 2,500 x 1,250 x 6 mm 5083 plate therefore weighs 2,500 x 1,250 x 6 / 1,000 x 2.66 = 49.9 kg. For round bar, weight (kg/m) = diameter squared x 0.00209. Our aluminum weight calculation guide has the full formula set and worked examples for coils, tubes and profiles.
What certificates and approvals do you supply with 5083?
Standard supply includes an EN 10204 3.1 mill test certificate covering chemical composition, mechanical properties, heat/lot number and dimensions. On request we provide EN 10204 3.2 (witnessed), class society certificates issued by ABS, DNV, Lloyd’s Register, BV, CCS or RINA, ASTM G66 exfoliation test reports, ultrasonic testing for thick plate, PMI and third-party inspection by SGS, BV or TUV before shipment.
What is the MOQ and lead time for 5083 marine aluminum?
MOQ is 500 kg per size for stock items – ideal for repair yards and prototype builds – and around 3-5 tonnes for production rolling of non-standard widths. Stock sizes ship in 3-5 working days; mill production runs 15-25 days depending on thickness, temper and width, plus transit. Cut-to-size, PVC film, edge chamfering and custom widths are available on all orders.
How do I get a price for 5083 marine aluminum?
Send us: alloy and temper (or the service condition and we will recommend), product form, dimensions and tolerance, quantity, the standard you need (ASTM B209/B928, EN 485, GB/T 3880), certification and class approval requirements, surface treatment and destination port. Our marine team replies with FOB and CIF pricing, MOQ and lead time within 24 hours by email or WhatsApp.
Related 5083 and 5052 Products
- 5083 Aluminum Sheets & Plates – marine tempers, cut to size
- 5083 Aluminum Coils – tank shells, ducting and long runs
- 5083 Aluminum Strips – precision slit and edge-conditioned
- 5083 Aluminum Tubes – pipe for seawater, fuel and hydraulic systems
- 5083 Aluminum Bars and 5083-H321 round bar – machined hardware
- 5083 Aluminum Wires – welding consumables and fabrication wire
- 5052 Aluminum Alloy and 5000 series aluminum – the wider marine family
- 5086 Aluminum Bars – the close alternative to 5083
Related Guides
- 5052 vs 5083 Aluminum Sheet for Marine Applications – part-by-part buyer’s guide
- Aluminum Tube for Marine Piping Systems – seawater, fuel, exhaust and hydraulics
- 5083 vs 6061 Tube and Pipe – alloy selection for marine lines
- Tube Wall Thickness & Pressure Rating Guide – sizing and corrosion allowance
- Aluminum Corrosion Resistance Guide – mechanisms, testing and prevention
- Aluminum Welding Guide – methods, filler metals and best practice
- Aluminum Bending & Forming Guide and CNC machining guide
- Aluminum Weight Calculation Guide – density formulas and worked examples
- Anodizing Guide and surface finishing guide
- Aluminum vs Steel and 3 series vs 5 series aluminum
- How to Source Aluminum from China – supplier due diligence
Get a 5083 Marine Aluminum Quote - Direct from the Mill
Tell us the alloy and temper (or the service condition), the form, dimensions, quantity, standard and certification you need, and the destination port. Our marine team replies with FOB and CIF pricing, MOQ, lead time and – where it helps – a recommendation on temper and thickness, within 24 hours.
HXM Aluminum · 5083 H116 / H321 plate, sheet, coil, strip, tube, bar and wire · ASTM B209 / B928, EN 485 · EN 10204 3.1 · MOQ 500 kg · Export packing to 60+ countries
