The common materials of cold formed spring can be divided into the following types according to the different heat treatment methods after forming.
The first type is the material that does not need quenching and only needs stress relief annealing after spring forming. This kind of material is mainly reinforced steel wire, including carbon steel wire, piano steel wire, stainless steel wire for spring and various oil quenched and tempered steel wire.
The second type is the material which only needs aging treatment after spring forming, such as beryllium copper wire and alloy for spring components.
The third type is the material that must be quenched and tempered. These materials are mainly annealed and hot-rolled, such as hot-rolled spring steel wire, silicon manganese spring steel wire, chromium vanadium spring steel wire, chromium silicon spring steel wire, etc.
With the development of metallurgical industry and the continuous improvement of spring performance requirements, in order to reduce equipment investment, reduce production costs, shorten the production cycle, and improve product quality and economic benefits, it is necessary to select the material that only needs stress relief annealing after forming to manufacture spring, that is, the first type. The third type of material that must be quenched and tempered after winding should not be used as far as possible.
The second type, which needs aging treatment (hardening and tempering treatment) after forming, is more used for springs with special requirements, such as corrosion resistance, weak magnetic field, electric conductivity and so on.