Summary for dissimilar metals corrosion Discussion
Dissimilar metals is the issue here: Rafael Rivero asked how to reduce electrolytic corrosion between a painted 6063-T5 extruded aluminum tube and structural steel tubing used for commercial building support. He wanted to know what material should be placed between the two metals. The answer from one respondent noted that this is a common problem in aerospace, where cadmium is used, but for commercial work he suggested galvanizing as the practical choice because it also provides good corrosion protection. The thread does not discuss other insulating materials or alternative coatings, so the main takeaway is to use a corrosion-protective barrier strategy rather than direct metal contact, with galvanizing offered as the recommended approach in this case.
Q. My questions is concerning corrosion due to contact between two dissimilar metals. I have an extruded alum. tube 6063-T5 and some structural steel tubing. The alum. is painted with a 2-part polyurethane paint. What type of material should be placed between the two dissimilar materials to help prevent electrolytic corrosion? The alum is used as an architectural feature in a commercial building and the steel is needed for structural support.
Any advise would be greatly appreciated.
Rafael Rivero
– Corona, California
2001
A. This is a common problem in aerospace where cadmium is used. For commercial work I would suggest galvanising, which would also give good corrosion protection.
Martin Trigg-Hogarth
surface treatment shop – Stroud, Glos, England
2001