Method for manufacturing cold rolling non oriented electrical steel through continuous casting and tandem rolling sheet bar

Abstract

The method for producing cold-rolled non-oriented electrical steel by using sheet bar and adopting continuous casting and continuous rolling process includes the following steps: a). utilizing the following components: C is less than or equal to 0.005%, Si is less than or equal to 3.5%, Mn is less than or equal to 1.5%, Al is less than or equal to 1.5%, P is less than or equal to 0.2%, S is less than or equal to 0.010%, N is less than or equal to 0.005%, O is less than or equal to 0.02% and the rest is iron and smelting; b). continuous casting, continuously casting molten steel to obtain sheet bar; c). heating, the temperature of sheet bar before which is fed into the furnace is 700-900deg.C, retaining said temperature for 30s-5min; heating sheet bar in ferrite phase area and heating temperature is less than or equal to 1120deg.C; d). hot-rolling, rolling in ferrite phase area, final rolling temperature is 800deg.C-950deg.C; e). coiling, coiling temperature is 500deg.C-900deg.C; and f). normalizing treatment or non-annealing treatment, acid-pickling, first cold-rolling or secondary cold-rolling with intermediate annealing to target thickness, then making final annealing so as to obtain the invented product.

Description

technical field [0001] The invention relates to a method for manufacturing non-oriented electrical steel, in particular to a method for producing cold-rolled non-oriented electrical steel products with good magnetic properties and low cost by continuous casting and rolling of thin slabs. Background technique [0002] The traditional continuous casting-hot rolling production line is a kind of steel product used by most steel plants, including the production method of cold-rolled non-oriented electrical steel products, which is characterized by good tolerance of production varieties and large output (a modernized The annual output of traditional hot rolling production lines can reach 3 million tons to 4 million tons). [0003] The traditional continuous casting to produce non-oriented silicon steel is carried out under the conditions of continuous casting casting speed of 0.8-1.5m / min and casting slab thickness of 210mm-250mm. According to the design of this process, the foll...

AI Technical Summary

Problems solved by technology

However, the problem of this process is that the slab is thin, the cooling speed is fast, and the temperature of the slab entering the furnace is high (≥900°C), resulting in only a small amount of precipitation of MnS and AlN in the slab before entering the furnace, and a large amount of precipitation after final rolling. The particles are small, which is very unfavorable to the grain growth of the finished plate during annealing, and the iron loss deteriorates

Due to the high heating temperature of the slab, the precipitates such as AlN precipitated when the slab is cooled below 900°C may be partly re-solidified, and then dispersed and precipitated after hot rolling, which is unfavorable for grain growth during final annealing

This patent limits the content of Si and Al on the one hand, (Si+2Al≤3%), because Si, Al are to expand the ferrite element, on the other hand when producing the electrical steel of higher Si, Al content (as Si ≥2% or Si+2Al≥2%), in order to heat the slab in the austenitic region, the C content must be increased, and decarburization must be performed during final annealing. On the one hand, the production cost is high (unit speed reduction), and on the other hand On the one hand, the magnetism is not good (prone to internal oxidation)