Spring steel is a kind of steel which is specially used to make springs and elastic elements because of its elasticity in the state of quenching and tempering. The elasticity of steel depends on its elastic deformation ability, that is, within the specified range, the elastic deformation ability makes it bear certain load, and there is no permanent deformation after the load is removed.
Spring steel should have excellent comprehensive properties, such as mechanical properties (especially elastic limit, strength limit, yield ratio), elastic reduction performance (i.e. anti elastic degradation performance, also known as anti relaxation performance), fatigue performance, hardenability, physical and chemical properties (heat resistance, low temperature resistance, oxidation resistance, corrosion resistance, etc.). In order to meet the above performance requirements, spring steel has excellent metallurgical quality (high purity and uniformity), good surface quality (strict control of surface defects and decarburization), accurate shape and size.
According to GB / T 13304 “classification of steel”, according to the basic performance and service characteristic I, spring steel belongs to mechanical structure steel; according to the quality grade, it belongs to special quality steel, that is, the steel requiring special strict control of quality and performance in the production process. According to the custom of our country, spring steel belongs to special steel.