The types of steel strands are divided into pre-stressed steel strands, unbonded steel strands, galvanized steel strands, etc. Different steel strands have different performance characteristics. The most commonly used steel strands are galvanized steel strands and prestressed steel strands. The diameter of commonly used prestressed steel strands ranges from 9.53mm to 17.8mm, with a small number of thicker diameter steel strands. The number of steel wires in each prestressed steel strand is usually 7, but there are also 2, 3, and 19 wires. The steel wires can have a metal or non-metal anti-corrosion layer on them. Coating with anti-corrosion grease or paraffin and then wrapping with HDPE is called unbonded steel strand. The manufacturing process is divided into single wire manufacturing and stranded wire manufacturing. When producing single wires, (cold) drawing technology is used. Depending on the different materials of the steel stranded wire (7 pieces) products, it can be high carbon steel wire rod, stainless steel wire rod, or medium and low carbon steel wire rod. If it is necessary to galvanize, electroplating or hot plating treatment should be carried out on the single wire.

During the manufacturing process of stranded wire, a stranded wire machine is used to twist multiple steel wires into a product. The prestressed steel stranded wire also needs to be stabilized after forming, and the final product is usually collected on a reel or completed as a reel less reel

Pre stressed steel strands are stranded steel cables composed of 2, 3, 7, or 19 high-strength steel wires, which have undergone stress relief treatment (stabilization treatment) and are suitable for prestressed concrete or similar purposes. According to the number of steel wires in a steel strand, it can be classified into 2 wire steel strand, 3 wire steel strand, 7 wire steel strand, and 19 wire steel strand. According to their appearance, they can be divided into smooth steel strands, scored steel strands, molded steel strands (compact), galvanized steel strands, epoxy resin coated steel strands, etc. It can also be classified according to diameter, strength level, or standard. As we can see from the description and list table, there are 15-7 specifications with their meanings Φ 5. 12-7 Φ 5. 9-7 Φ Pre stressing steel strands of grade 5 specifications. By 15-7 Φ For example, 5 reveals a steel wire with a nominal diameter of 5.0mm, and 7 Φ 5 revealed that 7 of these steel wires form a steel strand, while 15 revealed that 15 of these steel strands form a bundle of steel bars, which means "a bundle of steel bars composed of 15 7 wires (each with a total diameter of about 15.24mm and a size error of+0.40-0.20; each with a diameter of about 5.0mm).". According to the pre-stress standard of 60% -65%, it can withstand a tensile force of 2300-2500KN. The 5 manufacturing methods use high carbon steel wire rods, which are cold drawn into steel wires after appearance treatment. Then, a certain number of steel wires are twisted into strands according to the steel strand structure, and then stabilized through stress relief treatment. To extend durability, steel wires can have metallic or non-metallic coatings or coatings, such as zinc plating, epoxy resin coating, etc. To increase the grip strength with concrete, there may be scratches on the appearance. The pre-stressed steel strand pulled by the mold undergoes a mold compression process after being twisted, making the structure more compact and the surface more suitable for anchor gripping. The production of unbonded steel strand uses ordinary prestressed steel strand, coated with anti-corrosion grease or paraffin, and then wrapped with high-density polyethylene (HDPE). The important characteristics of prestressed steel strands are high strength and good relaxation performance, and they are also relatively straight when opened. The common tensile strength levels are 1860 megapascals for activity planning, as well as strength levels such as 1720, 1770, 1960, 2000, and 2100 megapascals. This type of steel also has a high yield strength, and it is widely used in most post tensioned and pre tensioned prestressed engineering projects. Smooth steel strands are the most widely used prestressed steel. Molded steel strands are important for lifting engineering and are also used in projects such as nuclear power. Galvanized steel strands are commonly used in bridge tie rods, cables, and external prestressing projects. The use of epoxy resin coated steel strands is similar to that of galvanized prestressed steel strands. Each country has standards for prestressed steel strands, such as the Chinese standard GB/T 5224, the American standard ASTM A416, the British standard BS 5896, the Japanese standard JIS G3536, the Australian and New Zealand standard AS/NZS 4672, and the Brazilian standard NBR-7483