Spring wire standard

Spring steel wire standards, scope of application and technological characteristics:

my country’s spring steel wire standards are based on ISO and JIS standards and are divided into steel categories. The current national and industry recommended standards include 6 carbon spring steel wire standards and 4 alloy spring steel wire standards. 888 spring net

Carbon spring steel wire standards, scope of application and process characteristics

The current national and industry recommended standards for carbon spring steel wire are divided into two types: one is cold-deformed strengthened steel wire, also known as cold-drawn spring steel wire. Cold-drawn carbon spring steel wire is first quenched to obtain the sorbite structure, and then the surface is phosphorous. The steel wire is drawn to the size of the finished product with a large reduction rate. The steel wire structure is fibrous, has high tensile strength and elastic limit, and good bending and torsion performance. Cold drawn spring steel wire has high dimensional accuracy, smooth surface, and no Oxidation and decarburization defects, fatigue life is relatively stable, is the most widely used spring steel wire.

Another type of carbon spring steel wire is martensitic strengthened steel wire, also known as oil quenched and tempered steel wire. The carbon steel wire can be quenched and tempered to obtain good comprehensive mechanical properties. When the wire size is small (φ≤2.0mm ), the strength indexes of oil-quenched and tempered steel wire are lower than those of cold-drawn steel wire after sorbitizing treatment. When the size of the steel wire is large (φ≥6.0mm), it is impossible to use a large reduction rate for sorbitized steel wire To obtain the required strength index, oil-quenched and tempered steel wire can obtain higher performance than cold-drawn steel wire as long as it is fully hardened. Under the same tensile strength conditions, martensitic strengthened steel wire has more High elastic limit. The metallographic structure of cold drawn steel wire is fibrous with obvious anisotropy. The metallographic structure of oil quenched tempered steel wire is uniform tempered martensite, which is almost isotropic. At the same time, oil quenched tempered steel wire Its relaxation resistance is better than that of cold-drawn steel wire, and its service temperature (150~190℃) is also higher than that of cold-drawn steel wire (≤120℃). In recent years, medium and large-sized oil-quenched and tempered steel wires have a tendency to replace cold-drawn steel wires.

Use characteristics and uses of spring steel wire:

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 a high elastic limit, yield strength and tensile strength. The higher the yield ratio, the closer the elastic limit is Tensile strength, so the more the strength utilization can be improved, 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.

The spring usually works for a long time under the action of alternating stress, so it must have a high fatigue limit, and good creep resistance 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. Springs used in precision instruments should have long-term stability and sensitivity. , The temperature coefficient should be low, the quality factor should be high, the after-effect should be small, and the elastic modulus should be constant. Springs that work 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 tempered spring steel wire are directly wound with the steel wire in the state of supply, and the spring is directly used after stress relief treatment after it is formed. The tensile strength of 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 steel wire is generally less than 8.0mm, and the specification of oil-quenched and tempered steel wire is generally less than 13.0 mm. In fact, springs with a diameter of 13.0mm are mostly spring steel wires in the lightly drawn state, which are cold-drawn and wound into shape and then quenched and tempered for use. Most of the steel wires with a diameter of 15.0mm are made by heating winding technology.