Description
Prestressed steel wire
Civil Engineering Terminology
Cold-drawn steel wire used to make the reinforcement in the tension zone of prestressed concrete members. Generally, concrete has high strength against compressive force, but is brittle and prone to cracking when subjected to tensile force. Prestressed concrete is to make the steel bars arranged in the tension zone of the component bear a tensile force in advance to generate pretension stress. The pre-tension stress on the steel bars reacts to the pre-tension stress in the tension zone, which can offset or reduce the tensile stress acting on the concrete by the external load, thus greatly improving the ability of the tension zone to resist tension, thereby reducing component size and saving materials. And reduce the self-weight of the components. Due to these advantages, prestressed concrete members have been successfully used in many projects such as large bridges, roof trusses, crane beams, industrial and civil precast floor slabs, railway sleepers, poles and pipe piles, large-diameter precast pipes, and atomic energy power stations. The production of prestressed steel wires has developed rapidly with the widespread application of prestressed concrete components. [
Chinese name prestressed steel wire
Foreign name: prestressing wire
Diameter 4mm, 4.8mm, 5.0mm, etc.
Treatment Process Heat Treatment and Cold Working
introduce
A general term for steel wires that are made from high-quality high-carbon steel hot-rolled wire rods through heat treatment and cold processing and are suitable for prestressed concrete reinforcement requirements. The carbon content of this type of steel wire is 0.65% to 0.85%, and the sulfur and phosphorus content are less than 0.035%. The tensile strength of steel wire is generally above 1470MPa, and its strength level has gradually transitioned from 1470MPa and 1570MPa to 1670~1860MPa. The diameter of the steel wire is above 3mm, and has gradually transitioned from 3 to 5 mm to 5 to 7 mm.
Prestressed steel wire began industrial production and application in the 1920s. After decades of development, a series of products with different characteristics suitable for different objects have been formed, including cold-drawn steel wire, straightened and tempered steel wire, low-relaxation steel wire, Galvanized steel wire and scored steel wire, etc. These products and the prestressed steel strands made of them have become the most widely used prestressed steel varieties in the world. [2]
Cold drawn steel wire
It is a smooth round steel wire drawn from high carbon steel hot-rolled circular wire rods after being quenched by lead solution. Since it has not been straightened and tempered, its elongation is low. Steel wire is delivered in rolls with diameters ranging from 500 to 1000mm. Mostly used in railway sleepers and concrete pressure water pipes. The diameter of cold-drawn steel wire produced in China is mostly 3mm, and a small amount is 4mm or 5mm. During production, the steel grade and wire rod diameter are selected according to the finished product specifications and performance requirements. Lead solution quenching is performed before drawing. The wire temperature is 890~930ºC and the lead temperature is 460~500ºC. After isothermal quenching, the strength increases to 1080~1180MPa, and the metallographic structure transforms into a sorbite 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 undergo processes such as pickling, phosphating or coating.
Straightening and tempering steel wire
Cold drawn steel wire is made by straightening and tempering. The straightening and tempering temperature is 460~500ºC, and its main function is to eliminate the internal stress generated during drawing. Compared with cold drawn steel wire, the yield strength of straightened and tempered steel wire is increased, and the ductility and stress relaxation properties are improved. The product is supplied in large coils with a coil diameter of 1.5 to 2m. It has good straightness after uncoiling, can be constructed as a single piece or in bundles, and is widely used to manufacture various types of prestressed concrete components.
low relaxation wire
Cold-drawn steel bars are stabilized (that is, tempered under tension) and named for their ability to reduce stress relaxation. Stress relaxation is an important characteristic of prestressed steel, that is, the stress loss of the tension element while maintaining a constant length. Its magnitude is expressed as the percentage of stress loss to the initial stress, which is called the relaxation rate. In engineering applications, the stress relaxation loss of prestressed steel accounts for a considerable proportion of the total prestress loss of structural components. Therefore, reducing the relaxation rate through stability treatment is an effective method to improve the performance of steel wires. When performing stability treatment, the tension is 0.4~0.5σb, and the tempering temperature is controlled between 350~400ºC. Because the steel wire generates a tiny strain of 0.9% to 1.3% under thermal tension, its ability to prevent dislocation transfer under the action of external forces is improved, which is manifested in that the elastic limit and yield strength of the steel wire are significantly increased, and the stress relaxation rate is reduced to 1/3~1/4 of straight tempered steel wire. When 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, the production and application of low-relaxation steel wires have made great progress.
galvanized steel wire
The hot-dip galvanizing process is used to coat the surface of the prestressed steel wire with a zinc layer of 250g/m2~350g/m2. Since prestressed steel wire is cold-worked steel with high strength, its surface is easily damaged and is more sensitive to media corrosion and stress corrosion than ordinary carbon steel. In particular, 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, density, defects, condensation water, cracks under stress, and the use environment of the structure of the wrapped concrete, resulting in stress. There is a great risk of failure of prestressed components due to corrosion and cracking. The galvanized layer can effectively protect the steel wire matrix. Galvanized steel wire is suitable for engineering structures with serious corrosion such as bridge cables and sewage pools.
Scored wire
Products made by pressing regular convex ribs or pits on the surface of smooth steel wire. Notching can improve the bonding performance between prestressed steel wires and concrete, and is mainly suitable for prestressed structural components constructed by the pre-tensioning method.ZHENGDE Prestressed steel wire is a high-strength steel, widely used in construction, bridges, tunnels, water conservancy projects and other fields. It has excellent mechanical properties and durability, and can effectively improve the bearing capacity and seismic performance of structures.
The material of the prestressed steel wire is mainly high-strength steel wire, and steel wires such as SWRH82B and SWRH77B are usually used. These steel wires have the characteristics of high strength, high toughness, high durability, etc., can withstand large tensile and bending forces, and also have good corrosion resistance and fatigue resistance.
The manufacturing process of prestressed steel wire mainly includes drawing, steel wire stranding, prestressing processing and other links. During the drawing process, the steel wire is drawn and annealed multiple times to make it meet the requirements of high strength and high toughness. In the wire stranding process, multiple steel wires are twisted into one prestressed steel wire to improve its bearing capacity and seismic performance. During the prestressing process, the prestressed steel wire is tensioned to a certain level of prestressing, so that it generates compressive stress in the structure, thereby improving the bearing capacity and seismic performance of the structure.
| GB | ASTM | JIS | DIN | NF | BS | OCT | ISO |
| 65 | 1065 | | Ck67 | XC65 | 060A67 | 65 | TypeDC,SC |
| 70 | 1070 | | | XC70 | 070A72 | 70 | TypeDC,SC |
| 85 | 1086 | SUP3 | Ck85 | XC85 | 060A86 | 85 | TypeDC,SC |
| 65Mn | 1066 | | | | 080A67 | 65Γ | |
| 55Si2Mn | 9255 | | 54SiCr6 | 56Si7 | Z51A58 | 55C2 | 56SiCr7 |
| 55Si2MnB | | | | | | | |
| 55SiMnVB | | | | | | | |
| 60Si2Mn | 9260 | SUP6,SUP7 | 60SiCr7 | 60Si7 | Z51A60 | 60C2 | 61SiCr7 |
| 60Si2MnA | | | | | | 60C2A | |
| 60Si2CrA | 9254 | SUP12 | | | | 60C2XA | 55SiCr63 |
| 60Si2CrVA | | | | | | 60C2XΦA | |
| 55CrMnA | 5155 | SUP9 | 55Cr3 | 55Cr3 | 525A58 | | 55Cr3 |
| 60CrMnA | 51605 | SUP9A | | | 525A60 | | |
| 60CrMnBA | 51B60 | SUP11A | | | | 55XΓP | 60CrB3 |
| 60CrMnMoA | 4161 | SUP13A | | 60CrMo4 | 705A60 | | 60CrMo33 |
| 50CrVA | 6150 | SUP10A | 50CrV4 | 51CrV4 | 735A51 | 50CrΦA | 51CrV4 |
| 30W4Cr2VA | | | | | | | |
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Shandong Zhengde Metal Manufacturing Co., Ltd. is a production and sales company integrating hot-rolled steel coils, cold-rolled steel coils, galvanized steel coils, color-coated steel coils, section steel, steel pipes, steel wires, metal mesh, stainless steel, aluminum, copper and other metal products integrated large enterprises. Five production and sales bases have been formed in Binzhou, Liaocheng, Wuxi, Tianjin, Jinan and Tai'an, with more than 100 production lines, 4 nationally recognized laboratories, 2 technical engineering centers, and 5 enterprise technology centers. Products are exported to more than 50 countries and regions such as North America, South America, Europe, Middle East region, Russia, Africa, North America, and other parts of the world.
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