How to choose between aluminium and steel for weight, strength and corrosion.
Aluminium and steel are the two common structural metals. They differ in weight, strength, corrosion resistance and cost, and each suits different jobs.
Aluminium is roughly one third the weight of steel for the same size. It suits parts where weight matters, such as gates, trays, canopies and portable equipment.
Steel is stronger for a given size and cost. It carries the load in beams, columns, frames and structural work where weight is not the main concern.
Aluminium forms its own oxide layer and resists corrosion without coating. Steel needs galvanising or paint to survive outdoors.
Steel is cheaper to buy and easier to weld. Aluminium costs more and requires different welding technique and filler.
Choose aluminium where low weight or natural corrosion resistance matters. Choose steel where strength and cost matter, and protect it with the right finish.