The choice of material for springs shall be determined according to the factors such as the nature of the tension spring's bearing load, stress state, stress magnitude, working temperature, environmental media, service life, requirements on conductive magnetic permeability, process performance, material source, and price.
Carbon spring steel wire and piano wire produce large residual stress after cold drawing. After machining the spring, there is a large residual stress, and the dimensional change after tempering is large, and it is difficult to control the dimensional accuracy. The oil quenched and tempered steel wire is modulized and strengthened after the steel wire is drawn to the specified size. There is basically no residual stress. After forming the spring, the temperature changes after a low temperature, the dimension change is small, and the heat stability is better than the cold drawing. Reinforce steel wire.
For the spiral spring material section, circular section should be preferred. Square and rectangular cross-section materials have strong bearing capacity, good impact resistance, and small springs, but the source of material is small. And the price is higher, except for special needs, generally try not to use this material. In recent years, research and development of circular steel wire flat instead of trapezoidal steel wire, has achieved very good results.