Compared with the low-carbon steel, strength, high hardness, good toughness, weldability, this steel is often used in a normalized state, but also for quenching and tempering. Uses: Suitable for hot forging, pressing and cutting plus approach, manufacturing section of small discontinuity large parts ≤150 ℃ operating temperature, such as screw, rod, shaft keys, rings, gears, sleeves, etc.; cutting good, widely used in automatic machining of bolts, screws, etc.; are also required for the manufacture of cold forging parts and welding parts; also be used as carburizing, carbonitriding and other parts. The steel used for forging and hot stamping machine parts, cold drawn, heavy and general machinery shaft, rod, rings, as well as on the use of machinery castings such as cylinder, turbine frame, rolling mill frame and parts, machine frame and flywheel.