Carbon Steel
Steel AISI/SAEIron-carbon alloy where carbon content (0.05–2.1%) primarily determines hardness and tensile strength. The most widely produced steel type.
Carbon steels contain 0.05–2.0% carbon as the primary alloying element, with manganese, silicon, and trace amounts of sulfur and phosphorus. They represent over 85% of all steel produced worldwide. Classified into low (< 0.3% C), medium (0.3–0.6% C), and high carbon (> 0.6% C) grades, each range delivers a distinct balance of strength, hardness, and ductility.
Designation Guide
AISI/SAE 10xx series designates plain carbon steels — the last two digits indicate carbon content in hundredths of a percent. For example, 1045 contains 0.45% carbon. The 11xx series adds sulfur for machinability, while 12xx adds sulfur and phosphorus. European EN standards use C-number notation (e.g., C45 ≈ AISI 1045).
Selection Tips
Choose low-carbon (1008–1025) for deep drawing, welding, and general fabrication. Medium-carbon (1035–1055) suits shafts, gears, and forged components where heat treatment can optimize hardness. High-carbon (1060–1095) is reserved for springs, cutting tools, and wear-resistant parts. Always consider the trade-off: higher carbon means greater hardness but reduced weldability and increased brittleness.