20CrMnTi (GB/T 3077) is a carburizing alloy round steel optimized for gears, with a chemistry that enhances surface hardness while maintaining a tough core:
0.17–0.23% C: Low enough to allow deep carburizing (0.8–1.2mm case depth) but sufficient to provide core strength.
1.00–1.30% Cr: Improves hardenability, ensuring the carburized surface achieves high hardness (58–62 HRC) for wear resistance.
0.80–1.10% Mn: Enhances hardenability and tensile strength in the core.
0.04–0.10% Ti: Refines austenite grains during carburizing (900–950°C), preventing grain growth and brittleness in the heat-affected zone.
0.17–0.37% Si, P ≤0.035%, S ≤0.035%: Balance machinability and toughness.
After carburizing and quenching, 20CrMnTi develops a hard, wear-resistant surface and a ductile core (30–35 HRC), ideal for automotive transmission gears and industrial gearboxes. It is equivalent to AISI 8620 (USA) and DIN 1.5815 (Germany), with Made-in-China listings marketing it as "20CrMnTi Alloy Steel Round Bar for Gear Manufacturing."