Yes, stainless steel and aluminium metals will react when wet, creating a red oxide, especially when salt is present.

The metal with the lower oxidation potential will corrode, in this case, the aluminium.

Corrosion develops when two dissimilar materials are combined in a corrosive electrolyte. A common question arises: does stainless steel react with aluminum? The answer is yes—this reaction occurs when aluminum comes into contact with stainless steel, potentially leading to galvanic corrosion.

Although aluminum reacts negatively to stainless steel, large surface areas of aluminum to stainless steel can be acceptable depending on local environmental conditions. Severe corrosion is likely to take place in a marine environment. However, there are methods that can be used to reduce this effect. A good way to reduce corrosion is to use an isolating coating or paint on the aluminum and the steel to isolate them electrically. Insulating washers are also effective in isolating the two dissimilar materials and creating a relatively safe surface area.

In addition to corrosion, discoloration of stainless steel, known as “tea staining,” may occur when it is combined with aluminium. This rust-colored staining results from the formation of aluminium oxide on the surface and can compromise both the appearance and durability of the materials. Regular maintenance, proper insulation, and the use of passivation—a process that improves the corrosion resistance of stainless steel—can effectively address these issues and maintain both aesthetic and structural integrity.

Another difference between stainless steel and aluminium is that the latter is not magnetic, while the former can be magnetic, depending on its composition.