§ 01 / CHEMISTRY

Chemistry and strength

Property5052-H325083-H1165086-H32
Magnesium content2.2–2.8%4.0–4.9%3.5–4.5%
Tensile strength228 MPa317 MPa290 MPa
Yield strength193 MPa228 MPa207 MPa
Elongation12%16%12%
Density2.68 g/cm³2.66 g/cm³2.66 g/cm³
FormabilityExcellentGood (harder to form)Good
WeldabilityExcellent (5356 filler)ExcellentExcellent
Cost (per kg)$3.20$4.10$3.80

Higher magnesium content in 5083 provides 40% more tensile strength and better performance as welded (retains more base-metal strength in weld heat-affected zone). 5052 is easier to form and machine but weaker.

§ 02 / MARINE

Marine corrosion resistance

All three alloys (5052, 5083, 5086) resist seawater corrosion far better than 6061 or 7075. They're the standard for marine applications:

  • 5052: ocean atmosphere (salt spray, rain), non-structural marine hardware, inland marine service
  • 5083: ship hulls, marine vessels, offshore platforms, pressure hulls — highly loaded structural marine
  • 5086: between 5052 and 5083 in strength and cost. Common in marine superstructures.

Unlike 6xxx series (6061), 5xxx aluminum is not heat-treatable — strength comes from work hardening (H-temper) only. But they retain strength better in weld zones because of this (no T6 to lose).

For parts that will be immersed or splash-zone:

  • 5083 for load-bearing
  • 5086 for structural but not highest-stressed
  • 5052 for non-structural fixtures, hardware, finishing
§ 03 / SENSITIZATION

Sensitization — a serious long-service issue

5xxx aluminum with high magnesium (>3%) — specifically 5083 and 5086 — can develop sensitization during prolonged exposure to temperatures above 60 °C. Beta phase (Al₃Mg₂) precipitates at grain boundaries, making the material susceptible to intergranular corrosion and stress-corrosion cracking.

Practical implications:

  • 5083 parts exposed to 60+ °C for thousands of hours can sensitize
  • Service environments to watch: engine compartments, exhaust areas, warm climates
  • Mitigation: specify 5383 (modified 5083) which is sensitization-resistant, or use H116 temper (resistant to sensitization), or lower service temperature

5052, with its lower 2.5% magnesium, does not sensitize at typical service temperatures. One reason 5052 remains popular despite being weaker — it's more foolproof.

§ 04 / WHEN

When to use which

01

Ship hulls, large marine vessels → 5083

The default for welded marine construction. High strength, excellent as-welded properties, proven decades of service. Specify H116 or H321 temper for sensitization resistance.

02

Marine hardware, deck fittings → 5052 or 5086

5052 for simple hardware. 5086 for structural marine brackets and bracketry where cost-performance balance matters.

03

Outdoor atmospheric exposure (non-marine) → 5052

General outdoor service, weather resistance. 5052 is the right default for non-marine outdoor work.

04

Pressure vessels, tanks → 5083

Cryogenic tanks, chemical tanks, pressure vessels in marine service. 5083 is the standard for welded pressure-holding applications at low-to-moderate temperatures.

05

Warm service (>60 °C) → Avoid 5083/5086 unless H116

For high-temp service or long-term exposure to 60+ °C, either specify H116 temper (sensitization-resistant) of 5083, or switch to 6061-T6 if strength margin allows.

§ 05 / MACHINING

Machining notes

All three machine similarly — like most aluminum:

  • Cutting speeds 300-600 SFM
  • Flood coolant recommended
  • Can form sticky chips with some grades — use specific aluminum-cutting geometry on tools
  • 5083 is slightly harder to machine than 5052 due to higher Mg content (tougher)
  • All three accept anodize (Type II), though color uniformity may be less predictable than on 6061

For anodized marine parts, 5086 is often preferred over 5083 because of more consistent color — the higher Mg in 5083 can cause slightly darker or uneven anodize.

READY WHEN YOU ARE

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