What is the chemical composition of 15# round steel, and why is it ideal for cold forming?
15# round steel (GB/T 699) is a low-carbon structural steel with a composition optimized for cold forming: 0.12–0.19% carbon (C), 0.17–0.37% silicon (Si), 0.35–0.65% manganese (Mn), ≤0.035% phosphorus (P), ≤0.035% sulfur (S), and trace elements (Cr ≤0.25%, Ni ≤0.30%).
The low carbon content (≤0.19%) ensures exceptional ductility, allowing it to be bent, stamped, or drawn without cracking-critical for applications like pipe fittings, automotive stampings, and structural brackets. Its international equivalents include AISI 1015 (USA), DIN C15 (Germany), and JIS S15C (Japan), all of which share similar cold-working properties. 15# has a tensile strength of 375–500 MPa and elongation of ≥27%, making it a staple in Chinese manufacturing for parts requiring complex shapes. Made-in-China listings frequently feature it as "15# Low-Carbon Round Bar for Cold Forming."