42CrMo round steel (GB/T 3077) is a chromium-molybdenum alloy engineered for high torque and fatigue resistance, with standout mechanical properties:
Tensile strength: 1080–1300 MPa after quenching (850°C) and tempering (550°C), enabling it to withstand extreme rotational forces in crankshafts and drive shafts.
Yield strength: ≥930 MPa, ensuring minimal deformation under sustained torque-vital for heavy machinery transmissions.
Impact toughness: ≥63 J at 20°C (Charpy V-notch), resisting fracture during sudden torque spikes (e.g., in industrial gearboxes).
Hardness: 298–341 HB after heat treatment, balancing wear resistance and machinability for precision-machined components.
Its chemistry (0.38–0.45% C, 0.90–1.20% Cr, 0.15–0.25% Mo) enhances hardenability and high-temperature strength, making it equivalent to ASTM 4140 (USA) and DIN 1.7225 (Germany). 42CrMo is widely used in wind turbine main shafts and automotive differential gears, with Made-in-China listings highlighting it as "42CrMo Alloy Steel Round Bar for High-Torque Components."
3. What does China's GB/T 1499.2-2018 standard specify for hot-rolled ribbed round bars in