As we all know, even if it is the same kind of steel wire, the quality of the steel wire produced is also different because the steelmaking process, wire drawing process and equipment of each steel plant are different. In addition, due to the different mechanical properties of the steel wire itself, the flattening process and equipment, it has different effects on the width and elongation of the steel wire in the flattening process. Therefore, when selecting the wire diameter, the following factors need to be considered.

　　 1. The influence of the tensile strength or hardness of the steel wire

　　The steel wire has high tensile strength and high hardness. During the flattening process, the resistance of the steel wire to longitudinal movement per unit volume increases and the elongation decreases. However, the unit volume of the steel wire moves laterally where the resistance is smaller, and the width increases. On the contrary, the steel wire is easy to elongate in the longitudinal direction, and its width is reduced. This is the reason why the steel wire has high hardness, easy to widen, low hardness, easy to stretch but not wide. In case of large deviation in the tensile strength of the steel wire and poor uniformity of the hardness of the steel wire rod, the width of the rolled billet will vary greatly, which will seriously affect the quality of the billet.

　　 2. The influence of steel wire surface roughness

　　During the rolling process, if the surface of the steel wire is rough, the relative friction coefficient between the steel wire and the roll will increase, the friction resistance will increase, the elongation of the steel wire will decrease, and the extension will increase. In the production, the material of the weighted leather is easy to spread because of its rough surface. On the contrary, the surface of the steel wire is smoother, because the friction resistance between the steel wire and the roll is small, it is easier to elongate and the spread is smaller. In order to prevent rust, the surface of domestic steel wire is coated with butter. If the butter is not clean, it is easy to slip during flattening, which also affects its width.

　　 Three, the chemical composition of steel wire and the influence of metallographic structure

　　The higher the carbon content of the steel wire, the worse its plasticity, the smaller the section compression and elongation of the steel wire, the more difficult it is to deform the steel wire during rolling, and the smaller its spread. For alloy steel wire, because the alloying elements dissolved in the solid solution can increase the hardening rate of the steel wire in cold work, its deformation resistance is large, its width is small during rolling, and it is easy to be brittle.