Stainless steel is an engineered alloy with base metals as iron, carbon, and a minimum of 10.5% chromium by mass, giving it resistance to corrosion and long term durability.
Iron is the primary base metal that provides mechanical strength and formability. It forms the bulk of the alloy, typically 50-72% by weight.
Chromium content ranges from 16-30% in common grades. It creates a protective oxide layer that prevents corrosion and regenerates when damaged.
Nickel (8-14% in 300 series) increases formability, toughness, and gives stainless steel its sleek appearance. It boosts resistance to acidic and alkaline conditions.
Crevice corrosion is one of the dangerous types of corrosion, but with the addition of 2-3% molybdenum, the resistance increases. It enhances resistance to chloride-driven pitting, a critical factor in marine and industrial applications.
Small amounts of carbon (≤0.08%) adjust hardness and tensile strength. Nitrogen supports tensile strength and corrosion resistance in specific grades.
Manganese (Mn) aids in deoxidations and hardness. Silicon (Si), phosphorus (P), and sulfur (S) control grain structure and machinability. Their levels remain low, typically under 1%.
Different stainless steel grades have different compositions that modify their performance and applications. It is important to understand these grades and their composition to make the right choice of specific industrial applications.