Five Types of Prestressed Concrete Steel Wire

Five Types of Prestressed Concrete Steel Wire

Summary

Prestressed concrete steel wire is a general term for steel wires made of high-quality high-carbon steel wire rods that have been pickled, phosphate, and then cold drawn or stabilized. This article will specifically introduce five types of prestressed concrete steel wire.

 five types of prestressed concrete steel wire

Prestressed concrete steel wire is a general term for steel wires made of high-quality high-carbon steel wire rods that are pickled, phosphate, and then cold drawn or stabilized. Prestressed concrete steel wire has the following five classifications according to the production process and surface condition.

Notched wire

A product in which regular ribs or pits are pressed on the surface of a smooth steel wire. The notch can improve the bonding performance between the prestressed steel wire and the concrete, and is mainly suitable for the prestressed structural members constructed by the pretensioning method.

Low relaxation wire

The cold-drawn steel bar is made by stabilization treatment (that is, tempering treatment under tension), named after the stress relaxation can be reduced. Stress relaxation is an important characteristic of prestressed steel, that is, the stress loss of a tension member under the condition of maintaining a constant length, which is expressed as the percentage of stress loss to the initial stress, which is called relaxation rate. In engineering applications, the stress relaxation loss of prestressed steel accounts for a large proportion of the total prestress loss of structural members. Therefore, reducing the relaxation rate through stability treatment is an effective way to improve the performance of steel wires. During the stability treatment, the tension is 0.4~0.5σb, and the tempering temperature is controlled between 350~400℃. Because the steel wire produces a small strain of 0.9% to 1.3% under hot tension, its ability to prevent dislocation transfer under the action of external force is improved. The elastic limit and yield strength of the steel wire are significantly increased, and the stress relaxation rate is reduced to the level 1/3~1/4 of straight tempered steel wire. Used under the same conditions, the residual stress in the prestressed tendons can be increased by 10% to 15%. Therefore, in the past ten years or so, the production and application of low-relaxation steel wires have made great progress.

Straightening and tempering steel wire

Cold drawn steel wire is straightened and tempered. The straightening and tempering temperature is 460~500℃, and the main function is to eliminate the internal stress generated during drawing. Compared with cold-drawn steel wire, the yield strength of straightening and tempering steel wire is improved, and the ductility and stress relaxation properties are improved. The products are supplied in large coils with a diameter of 1.5-2m. After uncoiling, it has good straightness and can be constructed by single or braided construction. It is widely used in the manufacture of various types of prestressed concrete components.

Galvanized steel wire

It is made of 250g/m2~350g/m2 zinc layer on the surface of prestressed steel wire by hot-dip galvanizing process. Because the prestressed steel wire is cold-worked steel, it has high strength, and the surface is easily damaged. It is more sensitive to medium corrosion and stress corrosion than ordinary carbon steel. Especially the steel wire has a small cross-sectional area and has been working under high stress for a long time. It is affected by factors such as the material properties, compactness, defects, condensate water, cracks under stress, and the use environment of the structure. Corrosion cracking causes a great risk of failure of prestressed components. The galvanized layer can effectively protect the steel wire matrix. Galvanized steel wire is suitable for severely corroded engineering structures such as bridge cables and sewage ponds.

Cold drawn wire

A high-carbon steel hot-rolled round wire rod is lead-quenched and then drawn into a smooth round steel wire. Because it has not been straightened and tempered, its elongation is low. The steel wires for prestressed concrete are delivered in coils with a diameter of 500~1000mm. It is mostly used for railway sleepers and concrete pressure water pipes. The diameter of cold-drawn steel wire produced in China is mostly 3mm, and at least 4mm and 5mm. During production, the steel grade and wire rod diameter are selected according to the specifications and performance requirements of the finished product, and lead quenching is carried out before drawing. The wire temperature is 890~930℃, and the lead temperature is 460~500℃. After austempering, the strength is increased to 1080-1180MPa, and the metallographic structure is transformed into a sorbate structure with excellent comprehensive properties. In order to ensure the surface quality of the finished product and facilitate drawing, the quenched wire rod needs to be pickled, phosphate or coated.

Different prestressed concrete steel wires not only have different manufacturing processes but also their actual uses. If you want to know more about the steel wires for prestressed concrete after reading the above content, you can contact us. We will provide you with professional consultation and effective solutions.

As a professional supplier of prestressed concrete products, we have accumulated many years of production and manufacturing experience in this field. We have a professional manufacturing team, strictly in accordance with the standard production, can provide customers with excellent performance products. Our perfect management team can provide customers with thoughtful after-sales service. If you want to buy our high-quality prestressed steel wire, please contact us immediately!