Stainless steel is an alloy composed primarily of iron, with chromium (at least 10.5%) and often nickel added. The chromium forms a thin, self-healing oxide layer on the surface that makes the alloy highly resistant to corrosion and rust. This corrosion resistance, combined with its strength and ease of cleaning, makes stainless steel the standard material for cutlery such as knives, forks, and spoons.
Other alloys serve different purposes. Permanent magnets are typically made from alnico (aluminium, nickel, cobalt) or ferrite alloys, which have strong magnetic properties that stainless steel lacks. Rock crushers require extreme hardness and impact resistance, so they use manganese steel (Hadfield steel), which work-hardens under impact. Bridges are built with structural steel or mild steel, chosen for tensile strength and cost-effectiveness rather than corrosion resistance.
The key property that links stainless steel to cutlery is its resistance to rusting and staining when in contact with food and moisture, making it safe, durable, and hygienic for everyday use.