Selection of spring material

The choice of spring material should be determined according to the nature of the spring load, stress state, stress size, working temperature, environmental medium, service life, requirements for conductive magnetization, process performance, material source and price.

In determining the shape and size of the material cross-section, should be preferred to the national standards and ministerial standards set by the series size, try to avoid the use of non-standard series of specifications of the material.

Medium and small spring, especially the spiral tension spring, should be given priority with the steel wire, lead bath and other cold cold drawn steel wire and oil quenched and tempered steel wire, with high strength and good surface quality, fatigue performance is higher than ordinary quenching Tempering wire, simple processing, good process, quality and stability.

Carbon spring steel wire and piano wire after cold drawing produce a large residual stress, after processing the spring, there is a large residual stress, tempering after a large change in size, it is difficult to control the dimensional accuracy. Oil quenched and tempered steel wire is in the wire is drawn to the specified size of the wire after the modulation and strengthening treatment, basically no residual stress exists, after forming the spring by low temperature tempering, small change in size, heat stability is better than cold Reinforced steel wire.

Large and medium-sized springs, for the load accuracy and high stress should be used cold drawn or cold drawn polished steel. For the load accuracy and low stress spring, hot rolled steel can be used.

Steel leaf spring generally use 55Si2Mn, 60Si2MnA, 55SiMnVB, 55SiMnMoV, 60CrMn, 60CrMnB grades such as flat steel.

Spiral spring material cross-section, should be preferred circular cross-section. Square and rectangular cross-section material, bear a strong ability, good impact resistance, but also make the spring miniaturization, but the material source less. And the price is higher, in addition to special needs, the general try not to use this material. In recent years, the development of round steel wire rolling instead of trapezoidal wire, and achieved good results.

In the high temperature work of the spring material, requires a better strength of the thermal stability, anti-relaxation or creep ability, antioxidant capacity, resistance to a certain degree of dielectric corrosion.

The working temperature of the spring increases, the elastic modulus of the spring material decreases, resulting in a decrease in rigidity and a smaller load carrying capacity. Therefore, the spring operating at high temperatures must understand the rate of change (modulus) of the elastic modulus and calculate the effect of the decrease in the load carrying capacity of the spring on the performance of the spring. According to GB1239, the common coil spring operating temperature exceeds 60 ℃, the shear modulus should be modified, the formula is: Gt = KtG where G - the elastic modulus at room temperature; Gt - working temperature t cut Variable modulus; Kt - temperature correction factor selected according to Table 2-98.

The use of spring materials at low temperatures should have good low temperature toughness. Carbon spring steel wire, piano wire and 1Cr18Ni9 and other austenitic stainless steel spring steel wire, copper alloy, nickel alloy has good low temperature toughness and strength.