The automobile transmission shaft and transmission shaft suspension material shall be medium carbon steel.

1. Low carbon steel has good plasticity, but low strength, hardness and weldability. It can be processed by cold stamping and can be used to manufacture various standard parts, shaft sleeves, containers, etc.

2. High carbon steel has poor plasticity, high hardness, poor fatigue strength and poor machinability, resulting in insufficient toughness and easy fracture of shaft parts. This kind of steel is suitable for manufacturing electrostatic pressure bearing wear-resistant parts, such as heavy rail, roller, etc. After proper heat treatment, it can also be made into spring, steel wire rope and other parts that need high hardness and high wear resistance.

3. The main function of the automobile transmission shaft is to support the rotation and transmit power. The working condition generally bears alternating torque and tension and compression load, and the journal and key components bear large friction and wear. The failure forms are mainly fracture and local excessive wear, and the fracture forms include fatigue fracture and overload fracture.

Therefore, when selecting materials, it is required that the materials have sufficient strength, stiffness and certain toughness, good wear resistance, high fatigue strength and good processability. In other words, the spindle is required to have good comprehensive mechanical properties.

4. After proper heat treatment (quenching and tempering, surface quenching, carburization, etc.), medium carbon steel can obtain better core toughness, surface wear resistance and other comprehensive mechanical properties.

Alloy quenched and tempered steel (medium carbon steel) is recommended. Ordinary quenched and tempered steel has poor hardenability and low mechanical properties. It is only suitable for parts with small size and light load. The alloying elements in alloy quenched and tempered steel can improve the hardenability, significantly enhance the surface hardening effect of heat treatment such as quenching, and do not reduce the core toughness. Alloy quenched and tempered steel is superheated (quenched and tempered, Quenched and tempered

It has high strength, high wear resistance and good plastic toughness, that is, it has good comprehensive mechanical properties.