Cold rolling method capable of preventing edge crack and brittle fracture of silicon steel with Si content more than or equal to 3.5 percent

Abstract

The invention relates to a cold rolling method capable of preventing edge crack and brittle fracture of silicon steel with Si content more than or equal to 3.5 percent. The cold rolling method comprises the steps of firstly preheating an uncoiled steel plate; spraying emulsion and fully closing the flow of the emulsion on the outlet sides of former 1-4 passes; conducting cold rolling by adopting a one-step cold rolling method; coiling, wherein the tension at the starting stage is enabled to be 60-80 percent smaller than the tension under set coiling speed to conduct tension control; conducting subsequent processes according to conventional steps. The cold rolling method capable of preventing edge crack and brittle fracture of silicon steel with Si content more than or equal to 3.5 percent has the advantages that not only can the silicon content be enabled to be more than 3.5 percent to improve the magnetic performance of the silicon steel plate, but also the steel plate can be free of edge cracks during cold rolling, the brittle fracture and reject rate is decreased to 0.15 percent, the rolling time of a single coil can be shortened by no less than 10 minutes, and compared with the prior art, the yield is improved by 28.64 percent.

Description

technical field [0001] The invention relates to a rolling method of silicon steel, in particular to a cold rolling method capable of preventing edge cracking and brittle fracture of Si≥3.5% silicon steel. Background technique [0002] As we all know, with the increase of silicon content, the magnetism and resistivity of silicon steel will increase, and the iron loss will drop sharply. The silicon steel with 3.3%~3.5% silicon content will lose P 15 / 50 ≤2.0W / kg, can produce high-end grades above 50W210. However, when the silicon content is ≥3.3%, the deformation resistance during cold rolling is large, and plastic deformation is extremely difficult; and because its normalization temperature is as high as 950~1150 ° C, the grain grows to more than 700 μm, resulting in a sharp drop in plasticity , the cold rolling process performance becomes poor, that is, in the rolling process, after the first and second passes of rolling, the cracks at the edge of the steel plate are dense. ...

AI Technical Summary

Problems solved by technology

However, its high starting rolling temperature will burn the surface of the guide roll, and because the whole coil is preheated, the temperature will be unevenly distributed in the radial and lateral directions of the steel coil, resulting in unstable rolling process and difficult plate shape. Precise control; in addition, the temperature of each pass during the rolling process is higher than that of the conventional process, and the process parameters such as the emulsion flow rate are changed, so that the rolling process does not reach the best matching mode