5083 Aluminum
Also: AA5083, UNS A95083, AlMg4.5Mn0.7, 5083-H116, 5083-H321, 5083-H111, 5083-O, Al 5083, marine grade aluminum plate
5083 is the marine plate alloy: the strongest common non-heat-treatable aluminum, welds without losing much strength, and resists seawater. Values for H116/H321.
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At a glance
| Density | 2.66 g/cm³ (0.0961 lb/in³) |
|---|---|
| Tensile strength | 317 MPa (46 ksi) |
| Yield strength | 228 MPa (33 ksi) |
| Hardness | 85-95 HB |
| Elongation | 16% (about 22% in O temper) |
| Modulus of elasticity | 70.3 GPa (10.2 Msi) |
| Thermal | Melts at 574-638 °C (1065-1180 °F); thermal conductivity ~117 W/m·K; not for sustained service above about 65 °C (150 °F) in wet environments |
| Composition | Al, 4.0-4.9% Mg, 0.4-1.0% Mn, 0.05-0.25% Cr, up to 0.4% Fe, up to 0.4% Si |
Typical values, H116 / H321 temper (strain hardened and stabilized, marine). O temper is about 290 MPa (42 ksi) tensile and 145 MPa (21 ksi) yield; ASTM B928 minimums for H116 are 305 MPa (44 ksi) tensile and 215 MPa (31 ksi) yield. Confirm against the mill certificate and the purchase spec.
- MachinabilityFair
- Gummy with long chips, like 5052 but harder, so it machines a little more cleanly. Sharp polished tooling, high speed and flood coolant; expect it to take longer than 6061. Fine for holes, edges and pockets on plate parts.
- WeldabilityExcellent
- Welds easily by MIG and TIG with 5183 filler (5356 acceptable for non-structural). As-welded tensile is about 275 MPa (40 ksi), the highest of the common alloys, and no post-weld treatment exists or is needed.
- FormabilityGood
- H116 plate bends at about 2-3x thickness inside radius; O forms easily. Cold forming raises the risk of sensitization later, so heavily formed marine parts are often specified in O and welded.
- Corrosion resistanceExcellent
- Excellent in seawater and salt spray in the H116 and H321 tempers, which are tested for exfoliation and intergranular resistance under ASTM B928. Loses that resistance if held above about 65 °C (150 °F) for long periods.
5083 is a high-magnesium (5xxx series) alloy that gets its strength from about 4.5% magnesium in solution plus manganese, not from heat treatment. That gives it the highest as-welded strength of any common aluminum alloy: a 5083 weld made with 5183 filler holds about 275 MPa (40 ksi) tensile, close to the parent metal, where a 6061-T6 weld drops to about 165 MPa (24 ksi). It is the standard alloy for welded aluminum hulls, workboats, superstructures, LNG tanks, pressure vessels, rail and truck bodies, and armor plate.
The H116 and H321 tempers exist for marine service: they are strain hardened and then stabilized so the microstructure resists intergranular corrosion and exfoliation, and plate sold under ASTM B928 is tested to prove it. H111 is the usual temper for extrusions, H112 and O for thick plate. In any temper 5083 stays ductile and tough down to cryogenic temperatures, which is why it is used for liquefied gas tanks.
Its limitation is heat. Above about 65 °C (150 °F) in sustained service, magnesium slowly precipitates at grain boundaries (sensitization) and the alloy becomes susceptible to intergranular corrosion and stress-corrosion cracking. Keep it out of hot, wet service, and machine it knowing that, like 5052, it is gummy and stringy compared with 6061.
Heat treatment
Not heat-treatable. The H116 and H321 tempers are strain hardened then stabilized by a controlled thermal treatment so the beta phase stays out of the grain boundaries; they cannot be produced in a job shop. Full anneal (O) is about 345 °C (650 °F). Any heating above roughly 65 °C (150 °F) for long periods, or above about 200 °C (400 °F) briefly, degrades the marine temper; welding is acceptable because the heat is local and brief. Stress relief is not practical without annealing.
Tempers and conditions
- O (annealed)
- H111 (extrusions)
- H112 (as-fabricated plate)
- H116 (marine plate, ASTM B928)
- H321 (marine plate, ASTM B928)
- H32 / H34 (sheet, less common)
Stock forms
- Plate 6-150 mm (1/4-6"), the main form
- Sheet
- Extruded bar, angle, tee and flat
- Tread plate
- Pipe and tube (limited)
- Forgings (limited)
Relative cost
Tier 3 of 5. About 1.3-1.6x the price of 5052 plate and above 6061; stocked mainly as plate by marine and industrial distributors. Cheap relative to the welded structure it enables, because no post-weld treatment is needed.
Typical applications
- Boat hulls, decks and superstructures
- LNG and cryogenic storage tanks
- Pressure vessels and process tanks
- Rail cars, truck and trailer bodies, dump bodies
- Armor plate and military vehicle hulls
- Drilling rig and offshore modules
- Welded frames and structures that see salt or cold
Process compatibility
How 5083 takes each process, and what to specify. Each process links to its own guide and to the shops that do it.
| Process | Rating | Notes |
|---|---|---|
| Welding | ExcellentExcellent | MIG with 5183 filler is the production process for hulls and tanks; the highest as-welded strength of any common aluminum. Can 5083 aluminum be welded? |
| MIG Welding | ExcellentExcellent | Pulsed MIG on plate 3 mm (1/8") and up; clean the oxide, use 5183 wire and keep interpass temperature low. |
| TIG Welding | ExcellentExcellent | AC TIG for thin sheet and root passes on tanks; 5183 or 5356 filler. |
| Sheet Metal Fabrication | ExcellentExcellent | Cut, rolled, bent and welded into hulls, tanks and bodies; the standard alloy for heavy aluminum fabrication. |
| Press Brake Forming | GoodGood | H116 plate bends at about 2-3x thickness inside radius; O tighter. Bend across the grain on thick plate. |
| Waterjet Cutting | ExcellentExcellent | The usual way to cut thick 5083 plate accurately with no heat-affected zone. |
| Laser Cutting | GoodGood | Fiber lasers cut sheet and plate to about 12-15 mm (1/2-5/8") with nitrogen; thicker plate goes to plasma or waterjet. |
| Plasma Cutting | GoodGood | The shipyard process for rough profiling of thick plate; leaves a heat-affected edge that is usually machined or welded over. |
| CNC Machining | FairFair | Gummy and stringy; acceptable for holes, pockets and edges on plate parts. Machine parts from solid in 6061 instead. |
| Anodizing | FairFair | Anodizes for protection, but the high magnesium and the rolled plate structure give streaky, uneven colour; not a cosmetic anodizing alloy. |
| Powder Coating | GoodGood | Standard on truck bodies and marine structures after conversion coating; keep the cure below about 200 °C (400 °F). |
| Chem Film (Chromate Conversion Coating) | GoodGood | Chromate or chrome-free conversion coating as a paint base; marine primers go over it. |
| Heat Treating | Not recommendedNot recommended | Cannot be hardened by heat, and heating degrades the H116/H321 marine temper. Only annealing to O is possible. |
| Aluminum Extrusion | FairFair | Extrudable in H111 for marine stiffeners and flat bar, but slow and limited to simple shapes; not a general extrusion alloy. |
Design and sourcing tips
- Specify "5083-H116" or "5083-H321" to ASTM B928 for any marine or salt-exposed plate; plain ASTM B209 5083 may not be tested for exfoliation resistance.
- Design welds to the as-welded strength (about 275 MPa / 40 ksi tensile with 5183 filler, per AWS D1.2) and call out the filler on the drawing.
- Keep sustained service temperature below about 65 °C (150 °F) in wet or salty service; for hot, wet applications use 5052, 6061 or stainless.
- Bend thick plate at 2-3x thickness inside radius across the grain, and prefer O temper for heavily formed parts that are welded afterward.
- Do not specify cosmetic anodizing on 5083; it streaks. Powder coat or paint over a conversion coating instead.
- For cryogenic tanks and pressure vessels, order plate to the ASME or ABS requirements on the PO; 5083 keeps its toughness down to -196 °C (-320 °F).
Frequently asked questions
- What is the difference between 5083 and 5052 aluminum?
- 5083 has about twice the magnesium, so it is stronger (317 vs 228 MPa tensile) and gives much stronger welds, and it is stocked in thick plate for hulls and tanks. 5052 is cheaper, forms tighter, is stocked mainly as sheet, and does not sensitize at elevated temperature. Use 5083 for welded plate structures, 5052 for formed sheet parts.
- What does 5083-H116 mean?
- H116 is a strain-hardened temper produced with a controlled process and then tested under ASTM B928 to show resistance to exfoliation and intergranular corrosion in seawater. H321 is a similar stabilized temper with the same tests. Either is the right call for marine plate; plain H32 or H112 is not.
- Can 5083 aluminum be welded?
- Yes, easily, and it is the reason the alloy exists. MIG or TIG with 5183 filler gives about 275 MPa (40 ksi) tensile across the joint with no post-weld treatment, roughly 85-90% of the parent metal. Clean the oxide and keep the interpass temperature low so the marine temper is not degraded around the weld.
- Why is 5083 not used above 65 °C?
- With more than about 3% magnesium, long exposure above roughly 65 °C (150 °F) lets a magnesium-rich beta phase precipitate along grain boundaries. The sensitized metal then corrodes intergranularly and can crack under stress in salt water. Short excursions, such as welding or a paint bake, are fine; continuous hot, wet service is not.
Processes that commonly use it
Related materials
Where to verify these values
- ASTM B928 and ASTM B209 (mechanical property minimums and marine temper tests)
- Aluminum Association, Aluminum Standards and Data
- AWS D1.2 (structural welding code, aluminum) for as-welded strengths
- Producer data sheets for H116/H321 marine plate
