The spring is used in the elastic range. After unloading, the spring should be returned to its original position. The smaller the plastic deformation, the better. Therefore, the steel wire should have high elastic limit, yield strength and tensile strength.
The higher the ratio is, the closer the elastic limit is to the tensile strength, and thus the higher the strength utilization, the stronger the spring force.
Spring, relying on elastic deformation to absorb impact energy, so the spring wire doesn't have to have very high plasticity, but there are at least able to withstand the spring forming of plastic, toughness and enough to withstand impact energy.
Spring is usually long work under alternating stress, so it has a high fatigue limit and good resistance to creep and relaxation.
The spring used in a particular environment will also have special requirements for the steel wire. For example, the spring used in the corrosive medium must have good corrosion resistance.
The spring used in precision instrument should have long-term stability and sensitivity, low temperature coefficient, high quality factor, small aftereffect, and constant elastic modulus.
The spring of working in high temperature condition is required to maintain sufficient elastic limit and good creep resistance at high temperature.
In addition, the forming process and heat treatment process of spring steel wire should be considered.
Cold drawn spring steel wire and oil quenching spring steel wire are directly wound spring in the supply state wire, and the spring is used directly after forming.
The tensile strength of cold drawn spring steel wire is slightly higher than that of oil quenching steel wire.
It is very difficult to make the spring wire, so the use of the cold-drawn spring steel wire is generally less than 8.0 mm, and the specification of oil quenching and tempering steel wire is generally less than 13.0 mm.
In fact, the diameter of 13.0mm spring is more than the spring steel wire of the light pull condition.
Most steel wire with a diameter of 15.0mm is made of heating coil.
