The steel has excellent hardenability, high strength and toughness, after quenching with good comprehensive mechanical properties. Good machinability, but the cold deformation plasticity, low, poor weldability. For creating high torsion and impact loading and hardenability of automobile steering shaft, front axle, drive shaft, crankshaft, gear, worm and other, can be used as shaft, connecting rod, a key, the bolts, nuts and other. Generally in the quenched and tempered use.