Combining different metals like aluminum and steel in urban outdoor furniture can create striking visual contrast and design interest. While possible, this practice requires careful consideration of metal compatibility to avoid galvanic corrosion - an electrochemical process that occurs when dissimilar metals contact each other in the presence of an electrolyte like rainwater.
Aluminum and steel sit relatively far apart on the galvanic series, making them particularly susceptible to this reaction. The aluminum typically acts as the anode and will corrode sacrificially to protect the steel (cathode). However, several effective strategies can prevent this issue. Using isolation materials like plastic or rubber gaskets between the metals breaks electrical contact. Powder coating both metals provides an excellent protective barrier, while stainless steel fasteners (which are close to aluminum on the galvanic scale) reduce corrosion risk.
Regular maintenance including cleaning and reapplying protective coatings will extend your furniture's lifespan. Well-executed mixed metal furniture offers the best of both worlds: aluminum's lightweight durability and steel's structural strength, creating urban outdoor pieces that are both aesthetically pleasing and functionally durable.