The short version
Choose 5052 if the part is bent, drawn, rolled or welded, and if it lives outdoors or near salt water. Choose 6061 if the part is machined from solid, carries a structural load, or needs to be anodized to a consistent finish. If the part is both heavily formed and heavily loaded, neither is right and the answer is usually 5083 or a design change.
Where the difference comes from
5052 is aluminum with roughly 2.5% magnesium. Magnesium strengthens the alloy by solid solution and by work hardening, which is why 5052 is sold in H tempers — H32 and H34 are the common ones. It cannot be strengthened by heat treatment; there is no T temper for it.
6061 carries magnesium and silicon in proportions that form magnesium silicide. That precipitate is what solution heat treatment and artificial aging develop, which is why 6061 is sold in T tempers, most often T6 and T651. The strength comes from the heat treatment, not from the rolling.
That single difference explains almost everything downstream: 6061 gets its strength from a thermal process that forming and welding both partially undo, while 5052 gets its strength from mechanical work that heat also undoes. Each alloy loses its advantage in the other one's process.
Typical minimum mechanical properties
Values below are commonly cited minimums for sheet and plate. They move with thickness, temper and standard, and the number that governs your part is the one on the mill certificate for your heat — not the one in a comparison table.
Welding and forming
- 5052 welds readily with 5356 filler and keeps most of its corrosion resistance across the joint. It is the usual answer for tanks, panels and marine trim.
- 6061 welds acceptably but the heat-affected zone loses roughly half the T6 strength unless the assembly is re-solution-treated and re-aged, which is rarely practical. Design the joint for the annealed condition, or design around welding.
- 5052 in O temper bends and draws well; H32 is stiffer and springs back more; H34 begins to crack on tight radii.
- 6061-T6 has limited bend capability. Where a 6061 part must be formed, form it in T4 and age to T6 afterwards.
Where each one is the wrong choice
- Do not specify 6061 below the waterline or in sustained marine immersion. Copper content and heat-treated microstructure make it the weaker corrosion choice.
- Do not specify 5052 for parts machined from solid at volume. It is gummier than 6061, produces a poorer surface finish and loads the tool.
- Do not specify 5052 where the design temperature sits continuously above about 65°C. High-magnesium 5xxx alloys sensitize in that band; the fix is a different alloy, not a different temper.
- Do not specify 6061 for architectural anodizing that has to match across batches unless you also specify film thickness class and single-heat supply.
Comparison table
| Property | 5052-H32 | 6061-T6 |
|---|---|---|
| Alloying system | Al-Mg (non-heat-treatable) | Al-Mg-Si (heat-treatable) |
| Tensile strength, typical min. | 210–260 MPa | 290 MPa min. |
| Yield strength, typical min. | 160 MPa min. | 240 MPa min. |
| Elongation, typical min. | 7–12% | 8–10% |
| Density | 2.68 g/cm³ | 2.70 g/cm³ |
| Weldability | Good, keeps corrosion resistance | Fair, HAZ loses strength |
| Formability | Good, especially O temper | Limited in T6 |
| Machinability | Fair, gummy | Good |
| Marine corrosion | Good | Poor below waterline |
| Anodizing response | Fair, can go gray | Good, consistent |
If you tell us the process the part goes through — bent, welded, machined, anodized — and the environment it lives in, the alloy decision usually makes itself. That is the question we ask first, before thickness and before price.