Use of spring steel wire

　　The spring is used within the elastic range, and should be restored to its original position after unloading. It is hoped that the plastic deformation is as small as possible, so the steel wire should have high elastic limit, yield strength and tensile strength. The higher the yield ratio is, the closer the elastic limit is to the tensile strength, so the higher the strength utilization ratio is, and the stronger the spring elasticity is.

　　Springs rely on elastic deformation to absorb impact energy, so the spring steel wire does not have to have high plasticity, but at least it must have plasticity that can withstand spring forming and sufficient toughness that can withstand impact energy.

　　Springs usually work under alternating stress for a long time, so they should have high fatigue limit and good creep resistance and relaxation resistance.

　　Springs used in specific environments also have some special requirements for steel wires. For example, springs used in corrosive media must have good corrosion resistance. The spring used in the instrument should have long-term stability and sensitivity, low temperature coefficient, high quality factor, small aftereffect and constant elastic modulus. Springs that work at high temperature are 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 also be considered. Both cold-drawn spring steel wire and oil-quenched tempered spring steel wire are directly wound with steel wire as supplied, and the spring is directly used after stress relief treatment. The tensile strength of cold-drawn spring steel wire is slightly higher than that of oil-quenched tempered steel wire. The elasticity of large-scale cold-drawn steel wire is too great, so it is difficult to wind the spring, so the specification of cold-drawn spring steel wire is generally less than 8.0mm, and the specification of oil-quenched tempered steel wire is generally less than 13.0 mm. In fact, the spring with a diameter of 13.0mm is mostly made of spring steel wire in light tension state, which is cold-drawn and wound into shape and then quenched and tempered. Most steel wires with a diameter of more than 15.0mm are made by heating and winding process.