Spring steel wire is a kind of steel wire used to make springs (SPRING) or wire-shaped parts (WIRE FORM). According to the different uses of springs, there are many types of spring wires needed to make springs, such as spring wires for mattress springs (abbreviated as mattress wires) with lower requirements, spring wires for shock absorbers, and springs for suspension springs. Steel wire, spring wire used for engine valve and spring wire used for camera shutter, etc. Although there is no unified standard classification name, the quality requirements of these wires are different. Spring steel wire can also be classified according to manufacturing process, such as raw drawn spring steel wire (without lead bath quenching treatment before drawing), lead quenched spring steel wire, galvanized spring steel wire, oil quenched spring steel wire, etc.
Springs are the most commonly used parts in the machinery industry and daily life. The spring is used within the elastic range and should return to its original position after unloading. It is hoped that the smaller the plastic deformation, the better, so the steel wire should have high elastic limit, yield strength and tensile strength. The higher the yield ratio, the closer the elastic limit is to the tensile strength, and thus the higher the strength utilization rate, the stronger the spring force.
The spring relies 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 to withstand impact energy.
Springs usually work for a long time under alternating stress, so they must have a high fatigue limit, and good creep and relaxation resistance.
Springs used in specific environments have some special requirements for steel wires. For example, springs used in corrosive media must have good corrosion resistance. The springs used in precision instruments should have long-term stability and sensitivity, low temperature coefficient, high quality factors, small aftereffects, and constant elastic modulus. Springs working under high temperature conditions are required to maintain sufficient elastic limit and good creep resistance at high temperatures.
In addition, the forming process and heat treatment process of the spring steel wire should also be considered. Both cold drawn spring steel wire and oil-quenched and tempered spring steel wire are directly wound with the steel wire in the supplied state, and the spring is directly used after the stress is relieved after being formed. The tensile strength of cold drawn spring steel wire is slightly higher than that of oil quenched and tempered steel wire. Large-size cold drawn steel wire has too much elasticity and it is difficult to wind the spring. Therefore, the specification of cold drawn spring wire is generally less than 8.0mm, and the specification of oil quenched and tempered steel wire is generally less than 13.0mm. In fact, springs with a diameter of 13.0mm are mostly spring steel wires in a lightly drawn state, which are then quenched and tempered after being cold-drawn into shape. Most steel wires with a diameter of 15.0mm or more are made by heating and winding.