How to solve the crack defect of high carbon steel wire

High carbon steel wire is mainly used to produce high strength low relaxation prestressed steel wire, steel strand, spring and other metal products. With the rapid development of China's national economy, the construction of infrastructure in various places has increased, and the demand for high-strength and low-slack prestressed steel wires is increasing. Therefore, the development of high-carbon steel wires has good development prospects.

In the process of drawing high-carbon steel wire rod, due to the complicated production process, it is very easy to cause the steel wire to break. The fracture types of high carbon steel wire drawing can be divided into two categories: one is that the source of the crack originates from the outer surface; the other is that the source of the crack exists inside the wire, which is caused by various reasons.

Several cases of cracks originating from the outer surface

Fracture caused by surface defects during wire hot rolling. Such defects are generally caused by surface defects such as scars and folds generated during hot rolling on the billet that have not been eliminated. For example, in the production process of the enterprise, the LX80A wire rod with a diameter of 5.5mm is drawn into a steel wire with a diameter of 1.6mm and then copper-plated. During the drawing process, a fracture phenomenon occurs, and the shape of the fracture is diagonally split.

Fracture caused by surface abrasion during wire coil packaging and transportation. In the production and transportation of high-carbon steel wire products, improper loading and unloading operations of coiled wires or irregular use of transportation tools by related companies are likely to cause wire surface scratches. This kind of situation generally occurs more frequently on raw materials with larger diameters. For example, some companies have broken phenomena during the uncoiling process of Ñ„13mm and SWRJ82B wire rods. The technical departments of the companies have found that the partial surfaces of the relevant samples have defects.

Fracture caused by defects in the drawing process. The fracture caused by the defects in the wire drawing process is mainly due to the lack of effective lubrication during the drawing process of wire rod production by related companies. The surface of the steel wire directly rubs against the wire drawing die, resulting in lateral cracks on the surface and causing fracture. For example, for the Φ13.5mm 80 # wire rod, the user company found that the wire rod has a high breaking rate during the drawing process.

Several sources of cracks inside the wire

Fracture caused by shrinkage and carbon segregation. This fracture of high-carbon steel wire is mainly due to the existence of shrinkage pores and carbon segregation defects in the raw materials. When the production company rolls wire products, if the more serious central shrinkage holes in the billet cannot be welded after rolling, these holes will be gradually elongated during the wire drawing process, showing irregularly shaped cracks. As a result, the wire breaks.

Fracture caused by non-metallic inclusions. Related companies found in the samples that 70 # wire is more likely to break during the drawing process. This fracture is mainly due to the presence of inclusions that cut the metal matrix. When the wire is drawn, the joint between the inclusions and the matrix forms a stress concentration. When this stress concentration reaches a certain level, it will crack the place so that Cause wire drawing breakage. Moreover, the increase in silicate inclusions will also accelerate wire drawing fracture.

Corresponding countermeasures

Since high-carbon steel wire rods have special features in terms of organization and performance compared to medium-low carbon steel rods, in order to prevent the drawing of broken wires, they must be strictly controlled at all stages of production, and corresponding countermeasures should be taken to ensure excellent drawing performance of the steel wire. And product quality.

For this reason, the relevant production enterprises should prevent large inclusions from entering the molten steel during the refining process; during casting, electromagnetic stirring and other processes can be used to ensure that the center of the billet is uniform.

In the distribution of the rolling reduction of wire rod, the enterprise should try to match the billet with the material, so that the center of the billet is loose, and the shrinkage hole can be welded; pay attention to adjusting the operation status of the equipment to prevent defects such as surface folding during wire rolling. . During the packaging and transportation of the finished wire products, the operation should be strictly in accordance with the regulations to avoid wire surface damage. During the drawing process, the drawing die should be kept intact to allow the drawn steel wire surface to be well lubricated.

Moreover, each wire break has its same points and different points. Surface folds formed by the wire rolling process or surface tissue damage caused by improper drawing processes can be avoided during the actual production of wire and wire. The surface defects of the wire rod caused by the surface cracks of the billet and non-metallic inclusions are related to the smelting process. Eliminating such defects depends on improving the level of smelting and continuous casting technology.

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