With the development of modern industry towards automation, high-speed and precision processing, it is required that steel has good cutting process performance, improves production efficiency, and adapts to large-scale production. Therefore, it is necessary to adopt more steel materials that improve and enhance cutting performance, in order to facilitate automatic cutting machine tool processing. This type of steel is mainly used for larger and less important parts. For example, parts commonly processed on automatic machine tools, such as screws, nuts, and other standard parts. Easy cutting steel also belongs to specialized steel.

Free cutting steel is mainly used to produce instruments, watch parts, automobiles, machine tools, and various other machines with strict requirements for size and roughness due to low stress; Standard parts with strict requirements for dimensional accuracy and roughness, but relatively low requirements for mechanical properties, such as gears, shafts, bolts, valves, bushings, pins, pipe joints, spring seat cushions and machine tool screws, plastic forming molds, surgical and dental surgical instruments, etc. [1]

The quality of free cutting steel represents the difficulty of material cutting. Due to the complex cutting process of materials, it is difficult to express the ease of cutting with a single parameter. Usually, the machinability of steel is comprehensively measured by tool life, cutting force, surface roughness, cutting heat, and difficulty in chip removal.

Attention should be paid when using: Free cutting steel can undergo final heat treatment, but generally does not undergo pre heat treatment to avoid damaging its machinability. The metallurgical process requirements of free cutting steel are stricter than ordinary steel, and the cost is higher. Therefore, only when it is necessary to improve the machinability of steel for large-scale production of parts, can it achieve good economic benefits.