5083 H116 Vs 5083 H321 Marine Grade Aluminum Plate: A Complete Selection Guide

5083 marine aluminum plate is the most widely used Al-Mg alloy for shipbuilding, yacht manufacturing and offshore structures. When sourcing marine-grade aluminum, many buyers and engineers struggle to distinguish between 5083-H116 and 5083-H321. Although both tempers meet ASTM B928 marine standards and pass ASTM G66/G67 anti-exfoliation corrosion tests, they differ greatly. Their manufacturing processes and practical performance also vary.

The essential gap lies in heat treatment technology. 5083-H116 is strain-hardened without low-temperature stabilization annealing. It provides dependable corrosion resistance in marine environments. Its mechanical properties stay stable. This makes it a cost-effective option for many marine projects.

In comparison, 5083-H321 gets an extra low-temperature stabilizing treatment. This treatment removes internal residual stress, refines the grain structure, and greatly improves resistance to stress corrosion cracking.

In terms of mechanical performance, both tempers feature identical tensile and yield strength, fully meeting marine load-bearing requirements. However, 5083-H321 provides higher elongation and better ductility, delivering superior bending performance and lower forming cracking risks. Its biggest advantage is outstanding post-weld stability. Low residual stress greatly reduces welding deformation and surface warpage. It helps ensure high precision for thick plates and large welded structures.

For practical use, 5083-H116 works well for ship superstructures, internal bulkheads, and deck covers. It also suits non-submerged thin-plate parts. It balances quality and cost.

5083-H321 is the preferred material for key marine facilities.
It is used for hull outer plates and underwater structures.
It also works well for thick plates.
It is suitable for long-term submerged offshore engineering parts.

As a trusted marine aluminum supplier, RAYIWELL MFG LIMITED / Top Metal provides certified 5083-H116 and 5083-H321 aluminum plates. We include complete MTC and corrosion test reports. We support customized sizes and professional export packaging to meet diverse global marine project demands.