Method for controlling nitrogen content of low nitrogen steel

Abstract

The invention provides a method for controlling the nitrogen content of a low nitrogen steel, a converter smelting process comprises the following steps: a ratio of high molten iron and low scrap steel is used, wherein the tapping temperature is no less than 1700 DEG C, ferrosilicon is used for preparing silicon to 0.4%, a gas cover is declined during a whole course of oxygen blowing period; the high carbon with carbon weight at 0.05-0.07% is used when tapping, carbon tapping can be carried out at a time, argon is not blown during the tapping process and at an argon station; a RH refining process comprises the following steps: the argon flow can be controlled at 150N1 / h from vacuum-pumping, the deep vacuum treatment time is controlled in 8-12 minutes, static duration after adding an alloy is 7-9 minutes; argon is continuously blown during continuous casting, and argon is used for casting protection. The method of the invention can effectively solve the nitrogen addition problem in steel, the nitrogen sample content in the argon station is controlled at 0.0011-0.0013%, the nitrogen sample content after finishing the RH treatment is controlled at 0.0013-0.0015%, and the nitrogen sample content of the finished products is controlled at 0.0016-0.0020%, and the degrading and steel judgment accidents due to improper component of the finished product nitrogen can be thoroughly eliminated.

Description

technical field [0001] The invention belongs to the field of smelting technology, and in particular relates to a method for producing steel grades with a nitrogen weight percentage content (hereinafter referred to as weight) of the finished product by a converter-RH (vacuum circulation degassing furnace) process (hereinafter referred to as weight) less than 0.0030%. Background technique [0002] At present, some steel types have put forward specific requirements on the range of nitrogen in the finished product, that is, the weight of nitrogen in the finished product is required to be ≤0.0030%. Compared with IF steel (ultra-low carbon steel), the chemical composition range of the finished nitrogen of this steel is narrower, so when producing this kind of steel, if no special process is adopted to control nitrogen, it will cause Nitrogen increase phenomenon, which leads to the nitrogen content in the finished product exceeds the range, frequent downgrading or steel modificatio...

AI Technical Summary

Problems solved by technology

[0002] At present, some steel types have put forward specific requirements on the range of nitrogen in the finished product, that is, the weight of nitrogen in the finished product is required to be ≤0.0030%. Compared with IF steel (ultra-low carbon steel), the chemical composition range of the finished nitrogen of this steel is narrower, so when producing this kind of steel, if no special process is adopted to control nitrogen, it will cause Nitrogen increase phenomenon, which leads to the nitrogen content in the finished product exceeds the range, and frequent downgrading or steel modification accidents directly affect the product quality pass rate and cause great economic losses to the enterprise