Decarburization annealing process for cold-rolled non-oriented silicon steel with high carbon content and low grade

Abstract

The invention provides a decarburization and annealing process of high-carbon middle-and-low-grade cold rolling orientation-free silicon steel. In the process, a horizontal type continuous decarburization and annealing coating unit is adopted, the thickness of a steel belt is 0.35-0.65mm, the operation speed of the steel belt is controlled to 70-100m/min, the tension of the steel belt in a continuous decarburization and annealing furnace is 1800-2200N; the temperatures of various furnace sections are controlled as follows: the furnace temperature of a preheating/ oxidation-free heating section is 1000-1100 DEG C, the furnace temperature of a radiant tube heating section is 900-920 DEG C, and the furnace temperature of a soaking section is 850-910 DGE C; apertures of a fan at a cooling section are 25-99% in turn; the pressures in the furnace are as follows: the pressure of an inlet is 25-30Pa, and the pressure of an outlet is 45-50Pa; and H2 and N2 are adopted as protective gas in the furnace, wherein the content of H2 is 25%-35%, the dew point value of the protective gas is 35+/-5 DEG C, and the flux of the protective gas is 350-420m<3>/h. In the invention, the process is adopted so as to not only ensure that the steel belt is smooth, the magnetic property, magnetic ageing and the like of the steel belt meet technical requirements, the qualified rate of a finished product is improved and waste quantity is reduced but also ensure that production is smoothly carried out.

Description

technical field [0001] The invention belongs to decarburization annealing technology, in particular to a process for continuous decarburization annealing of non-oriented silicon steel with high carbon content and low grade by using a horizontal continuous decarburization annealing coating unit. Background technique [0002] The content of C in the finished cold-rolled non-oriented silicon steel of medium and low grades is required to be less than 0.003%, because carbon is an extremely harmful element, and it forms an interstitial solid solution with iron, causing severe distortion of the crystal lattice and causing a large internal stress to reduce the magnetic properties, P 15 Increased, and severe magnetic aging. [0003] Therefore, it is required that the C content of hot-rolled steel coils used as cold-rolled raw materials is ≤0.005%, so as to ensure that the low-grade cold-rolled non-oriented silicon steel is cold-rolled, and the C content can be reduced to the required...

AI Technical Summary

Problems solved by technology

[0004] In actual production, due to various reasons, the C content in hot-rolled steel coils is too high, greater than 0.005%, that is, steel coils with high carbon content. Reducing the process requirements to <0.003%, resulting in a decline in the magnetic properties of the finished product, leading to a decrease in the qualified rate of the brand, a slight impact on the magnetic properties will result in a reduced brand, and a serious impact on the magnetic properties will form waste products, causing difficulties in production and operation

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