PC steel wire and strand is a new type of economic and efficient construction steel that is developing at a fast pace. Its quality directly affects the safety of the project. There are many factors that affect the quality of PC products. This paper will be combined with the actual production of the drawing process that often occurs in the broken wire phenomenon for the analysis of the causes of fracture, and proposed measures to solve it.
Due to the comprehensive update of steelmaking technology, continuous casting instead of monument die casting for rapid and continuous production, and continuous casting billet in the crystalline nucleation solidification process can not be like die casting in the production of the method of the heating cap to reduce the final solidification shrinkage formed by the organization of loose and inclusions and defects such as million points of segregation. As a result, the inclusions in the central area of the final solidification of the continuous casting billet, i.e. the central equiaxial crystal zone, cannot be effectively eliminated. Moreover, the cooling and solidification of the liquid metal in this region is slow, resulting in coarse grain organization. In addition, this area is not supplemented by external liquid during crystallization shrinkage, resulting in shrinkage or loosening in this area. Thus, in the drawing process, the deep processing performance of the metal in the central area is poor, and the tensile strength and elongation index are much lower than the fine crystal area and columnar crystal area in the outer layer of the cast billet. When the compression rate reaches a certain level during drawing, the area will form cracks prematurely and expand outward, eventually leading to fracture fractures.
In addition, the casting billet in the high line rolling, if the final rolling temperature is too high, the control cooling process is slow cooling speed. The ferrite will first precipitate on the grain boundary, grow and can form a network, and finally transformed into a network of ferrite. In the pulling force, this organization is prematurely broken, so that the steel matrix appears in a large number of microscopic voids. Thus, the formation of microcracks in the grain boundaries. With the increase in compression rate, the rapid expansion of cracks gathered, eventually leading to PC steel wire fracture.
To eliminate this series of defects, steelmaking must be taken to refine and protect the casting technology to improve the purity of the steel and reduce the degree of segregation. To ensure uniformity in the cross-section of the billet.
PC products in the production of drawing wire breakage are caused by a variety of reasons: impure steel, loose tissue, inclusions, and serious segregation will cause wire breakage; coil surface quality is poor, the presence of mesh ferrite in the center of the coil will also cause abnormal wire breakage; improper operation is also the main reason for wire breakage. In order to improve the quality of PC products, it is necessary to strictly control all aspects of production from steelmaking, continuous casting, rolling, and drawing.
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