Method for controlling nitrogen content of low nitrogen steel
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A nitrogen-content, low-nitrogen steel technology, applied in the direction of manufacturing converters, improving process efficiency, etc., can solve problems affecting product quality qualification rate, enterprise economic loss, nitrogen increase, etc., to eliminate downgrading and steel modification accidents, and solve Effects of Nitrogen Problems
Inactive Publication Date: 2012-11-21
ANGANG STEEL CO LTD
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[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
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Embodiment 1
[0018] A 260-ton top-bottom double-blown converter and a 260-ton RH furnace are used to produce ST16 steel grades.
[0019] 1. Control of top and bottom double blowing converter:
[0020] a. The loading amount of the converter adopts high molten iron and low scrap steel ratio, the scrap steel adding amount is 25 tons, and the tapping temperature is 1750°C.
[0021] b. The actual measured weight of Si in molten iron is 0.3%, and ferrosilicon is added to mix silicon until the weight of Si reaches 0.4%.
[0022] c. The fume hood is lowered during the whole process of oxygen blowing, and the argon is blown during the whole process of bottom blowing.
[0023] d. High-strength carbon is used for tapping the converter, and the carbon weight is controlled at 0.06%. The carbon is tapped at one time to avoid overblowing. And no argon will be blown during the tapping process and after entering the argon station.
[0024] 2. RH control:
[0025] a. Increase the flow rate of argon gas....
Embodiment 2
[0031] The 260-ton top-bottom double-blown converter and 260-ton RH furnace are used to produce M3A35 steel.
[0032] 1. Control of top and bottom double blowing converter:
[0033] a. The loading amount of the converter adopts high molten iron and low scrap steel ratio, the scrap steel adding amount is 20 tons, and the tapping temperature is 1740°C.
[0034] b. The measured weight of Si in molten iron is 0.25%, adding ferrosilicon and silicon until the weight of Si reaches 0.4%.
[0035] c. The fume hood is lowered during the whole process of oxygen blowing, and the argon is blown during the whole process of bottom blowing.
[0036] d. High-strength carbon is used for tapping the converter, and the carbon weight is controlled at 0.07%. The carbon is tapped at one time to avoid overblowing. Argon will not be blown during the tapping process and after entering the argon station.
[0037] 2. RH control:
[0038] a. The flow of argon gas has been controlled at 150Nl / h from th...
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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...
Claims
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