What 5083 Aluminum Plate Is
Aluminum alloy 5083 is an aluminum-magnesium alloy containing magnesium with small amounts of manganese and chromium. It is particularly resistant to attack from seawater and industrial chemicals, which makes it one of the most widely specified alloys for marine and offshore construction. Both 5083-H116 and 5083-H321 are produced from the same alloy grade, so their chemical composition is identical; the difference lies in the temper processing, which changes mechanical properties and corrosion behavior. Both grades are commonly used for tank bodies, vehicle fuel tanks, bus body panels and shipbuilding.
Understanding the H116 Temper
The H116 temper applies to products made from 5xxx-series alloys with a nominal magnesium content of about 3 percent or more. Products are typically strain hardened during the final operation to define stable tensile property limits and to meet required levels of corrosion resistance in accelerated corrosion tests. H116 material is suitable for continuous use at temperatures no higher than about 66°C (150°F). Corrosion testing for this temper includes intergranular and exfoliation testing, which verifies that the material resists the forms of corrosion most relevant to marine service.
Understanding the H321 Temper
The H321 temper is achieved by strain hardening followed by a stabilizing heat treatment. The stabilization step improves the stability of the mechanical properties and corrosion performance over time. In practice, 5083-H321 typically offers strong corrosion resistance with consistent performance, and it is often described as one of the stronger 5083 tempers for extreme environments. H116 and H321 have broadly similar mechanical qualities, and both exhibit good corrosion resistance after proper surface preparation and coating; the final choice depends on the application's corrosion and strength requirements.
Typical Properties and Composition
The chemical composition of 5083 plate is controlled within tight limits: silicon max 0.40 percent, iron max 0.40 percent, copper max 0.10 percent, manganese 0.40-1.0 percent, magnesium 4.0-4.9 percent, chromium 0.05-0.25 percent, titanium max 0.15 percent, zinc max 0.25 percent, with the balance aluminum. Typical mechanical properties for plate include a tensile strength of about 305 MPa for 5083-H116 and 305-358 MPa for 5083-H321, a yield strength of about 215 MPa for both, and elongation around 10 percent. Because 5083 is not a heat-treatable alloy, its strength comes from work hardening and stabilization rather than from solution treatment and aging.
Applications and Selection Advice
5083-H116 is widely used in marine environments for ships and offshore structures where a combination of high strength and corrosion resistance is required; the more stringent controls relative to softer tempers make it suitable for demanding service. 5083-H321 is commonly used in demanding industrial applications such as pressure vessels, ship structures and some aerospace applications. When selecting between the two, consider the service temperature, the severity of the corrosive environment, whether the plate will be welded and how the welds are protected, and the mechanical property requirements of the design. For certified marine service, specify the governing standard, such as ASTM B928 for marine-grade 5xxx plate, and request a mill test certificate documenting composition and mechanical properties.
FAQ
Q: What is the difference between 5083-H116 and 5083-H321?
A: Both are made from the same alloy. H116 is strain hardened with final-operation controls for corrosion resistance, while H321 is strain hardened and then stabilized by heat treatment, typically providing consistent strength and corrosion performance.
Q: Which temper is stronger, H116 or H321?
A: Typical mechanical properties are broadly similar, with H321 often showing a slightly higher tensile range; the practical difference is more about corrosion performance and consistency than raw strength.
Q: Can 5083 plate be used for continuous high-temperature service?
A: H116 material is generally suitable for continuous use at temperatures no higher than about 66°C (150°F); higher service temperatures should be reviewed against the applicable standard.
Q: Why is 5083 chosen for shipbuilding?
A: Its aluminum-magnesium composition resists seawater and industrial chemical attack, it remains weldable, and it offers high strength at low weight, which improves payload and fuel economy.
Q: What corrosion tests apply to H116 plate?
A: Intergranular and exfoliation corrosion tests are typical for H116 marine plate, which is why the temper is specified for demanding environments in standards such as ASTM B928.
Q: What should buyers request when ordering 5083 marine plate?
A: Specify alloy, temper and governing standard, such as 5083-H116 to ASTM B928, plus thickness, width, length and a mill test certificate documenting composition and mechanical properties.
