Springs formed in a cold state (diameter or thickness generally less than 10mm)
Heat treatment process of hot-formed springs-most springs formed by this method are combined with hot-forming and heat treatment, while most coil springs are heat-treated after hot forming. The heat treatment method of this kind of spring steel is quenching + intermediate temperature tempering, and the structure after heat treatment is tempered troostite. This kind of organization has high elastic limit and yield limit, and has certain toughness.
The heat treatment process of cold-formed springs–for springs made of cold-rolled steel plates, steel strips or cold-drawn steel wires, the material is strengthened due to cold plastic deformation, and has reached the required performance of the spring. Therefore, after the spring is formed, it is only necessary to perform stress relief treatment in the range of about 250C and heat preservation for about 30 minutes to eliminate the door stress of the cold formed spring and to finalize the shape of the spring.
Heat treatment of heat-resistant spring steel-The valve springs of internal combustion engines work at higher temperatures, and some still have corrosive atmospheres. Therefore, special spring steels and appropriate heat treatment specifications must be selected.