I am trying to compare two aluminium alloys: 5052-H32 6061-T6 One is describes as having "very good corrosion resistance" and the other has "high resistance to corrosion". Which is best? Is there a more scientific way to compare them for corrosion resistance? Surely the breakdown of alloy components (see links above) is a good indicator? Perhaps the amount of chromium? Can anyone give me an idea of how the two alloys would compare in terms of corrosion resistance?
5052-h32 has better corrosion resistance than 6061-t6 according to this source: Corrosion of aluminum and aluminum alloys By Joseph R. Davis http://books.google.ca/books?id=iEe...d aluminum alloys&pg=PA36#v=onepage&q&f=false
It also depends on the environment. The generic phrases "very good corrosion resistance" etc will likely refer to resistance to surface corrosion in standardised atmospheric conditions. Under specific conditions (marine etc) you might not find the same ranking. Some grades will also be more or less susceptable to more specific corrosion damage (stress corrosion cracking, pitting and the like) depending on the presence of particular substances in the environment (e.g. chloride ions) and perhaps localised mechanical conditions. Cheers Andrew
Both have good corrosion resistance in salt water. The primary differences in these two alloys lies elsewhere. 5052-H32 is a non-heat treatable strain hardening alloy. It has good toughness at cryogenic temperatures, but it does tend to suffer from stress corrosion above about 150F, though not as badly as other 5000 series aluminum alloys that have more Magnesium. It is used in structural applications requiring moderate strength and where forming or welding are required. 6061-T6 is a solution-heat treated and aged alloy with similar strength to the 5052-H32. It also has good toughness at low temperatures and is used for light structure, but doesn't suffer from stress corrosion cracking to the extent that 5052-H32 does. Both are used in marine applications and are weldable but the 6061 returns to a near-annealed state in the heat effected zone around the weld. Probably for this reason more than any other 5052-H32 is preferred over 6061-T6 in marine applications (so as to avoid a heat-treat after weld requirement). Neither are particularly strong compared to other aluminum alloys (compare 7075, 7050, 2024 series). Another thing to be aware of when designing with aluminum alloys is that none of them exhibit an endurance limit like steel does: Over time, aluminum fails even at very modest loads.
Thanks all for the advice. Just a quick update: I did a 1000hr salt-spray test on both alloys and 5052 H32 came out best. A great result
