Leaf springs work under cyclic bending, torsion and other alternating stresses, and withstand multiple effects of sealing ring springs such as tension, compression, torsion, extrusion, fatigue, corrosion, and sometimes also bear extremely high short-term impact loads. Therefore, spring steel is required to have high tensile strength, yield strength, yield ratio, plasticity, toughness, hardness, elastic limit, and fatigue strength.

At present, the production of leaf spring mainly adopts quenching+medium temperature tempering to obtain uniform and fine tempered troostite structure of leaf spring to meet the requirements of leaf spring performance. The characteristics of leaf spring working conditions determine that the spring steel must meet the following excellent performance: leaf spring is used under the conditions of dynamic coil spring loads such as alternating stress, vibration, impact, etc. Therefore, in addition to tensile strength and hardness, the spring steel must have good mechanical properties such as elastic limit, proportional limit, plasticity and toughness, to ensure that the leaf spring can meet the basic requirements of various properties in use; During the working process of leaf spring, the stress on the surface is the largest, which requires the spring surface to have high tensile strength and hardness; Fatigue and elastic degradation are the two main failure forms of leaf springs. In order to prolong the service life of the spring, when improving the design stress of the spring, it is necessary to ensure that the spring steel has excellent anti-fatigue performance and anti-elastic degradation ability; Good physical and chemical properties are required, mainly including heat resistance, low temperature resistance, oxidation resistance and corrosion resistance; When the leaf spring bears various loads, the surface stress is the largest, and it is easy to be damaged. Therefore, the surface quality of the spring steel billet has a great impact on the production of leaf spring. Decarburization reduces the anti-fatigue and anti-ballistic performance of the leaf spring. Therefore, it is necessary to ensure the good anti-decarburization performance of the spring steel.