How to prevent galvanic corrosion between aluminum and stainless steel

Aluminium and stainless steels (austenitic, duplex and super duplex stainless steels) are sufficiently different in terms of their galvanic potential for galvanic corrosion to occur if they are inadvertently coupled. In this couple, the aluminium would act as the anode in an electrochemical cell and be preferentially attacked.

Galvanic corrosion can be prevented by a variety of means. In the first instance, only using metals in combination that are relatively close to each other in terms of ‘galvanic potential’ would limit or avoid galvanic corrosion. However, if that is not possible, it will require a degree of intervention. At the simplest level, this could involve isolating the two metals, perhaps using gaskets or coatings, although this can lead to other problems such as creating crevices. Adding a third metal in to the combination, which is more likely to corrode than the first two will effectively create a sacrificial anode. Alternatively, reducing the corrosive nature of the environment may be possible using corrosion inhibitors in the solution.

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