If I were choosing urban outdoor furniture, I’d compare aluminum and steel on the specific alloy, coating system, environment, and maintenance plan—not just the base metal. Aluminum is naturally corrosion-resistant because it forms an oxide layer, and marine-grade 6061 or 6063 aluminum with powder coating handles rain, humidity, and salt air well. It is lighter, easier to move and install, and it will not rust red like carbon steel. But aluminum is softer and can dent under heavy impact; thin-wall extrusions may also flex. Steel—especially stainless or hot-dip galvanized carbon steel—is stronger and stiffer, which helps resist vandalism and heavy public use. However, carbon steel depends on a flawless coating; chips and scratches can lead to rust creep. Stainless steel is durable but costly and can still stain or corrode in salty or chlorinated environments if the grade is wrong.
For city parks, transit stops, plazas, and coastal promenades, I’d assess the climate first: salt, de-icing salts, pollution, UV, and standing water. Specify aluminum with marine-grade alloy, thick walls, welded joints, drainage, and a multi-stage powder coat. Specify steel with hot-dip galvanizing plus powder coating, stainless hardware, sealed welds, and touch-up kits. Check load ratings, joint design, and fade and scratch resistance. In high-abuse areas, steel’s mass and stiffness often last longer structurally; in wet, salty, or humid settings, aluminum usually demands less corrosion maintenance. If appearance matters, both need cleaning and periodic coating inspection. I’d request samples, salt-spray test data, coating thickness, warranty terms, and a five-to-ten-year maintenance estimate. Durability isn’t just years—it’s how the furniture performs with the maintenance budget you’ll actually fund.