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A method of controlling nitrogen content in n80 steel

A nitrogen content and pressure control technology, applied in the field of nitrogen content control in N80 steel, can solve the problems of unstable alloy yield, high cost, grain boundary weakening, etc., to improve production efficiency and product quality, low cost, controllable The effect of nitrogen content

Active Publication Date: 2012-02-01
ANGANG STEEL CO LTD
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Problems solved by technology

The cost of the former is high, and the alloy yield is not stable; although the cost of the latter is low, but the process of blowing nitrogen into the ladle is adopted, the control of nitrogen content is unstable, because N80 steel requires high content of [N] and [V] , resulting in the precipitation of [VNC] compound on the grain boundary, which destroys the continuity of the grain boundary, causes the grain boundary to weaken, and cracks under the action of external force, resulting in cracks in the product, which has a great impact on product quality

Method used

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Embodiment Construction

[0010] A method for controlling nitrogen content in N80 steel, the measures taken by the method are:

[0011] 1. Stabilize the LF slagging operation, improve the deoxidation system, control the weight and composition of slag, and stabilize the state of nitrogen blowing in the process: the amount of slag added is 0.40-0.48kg / ton of steel, and R is controlled at 2.5-3.2; Silicon deoxidation, control [0]≤15ppm in steel;

[0012] 2. During the VD pressure-holding process, formulate the appropriate nitrogen blowing flow rate, pressure, and time to stabilize the nitrogen content after breaking the void: blow nitrogen at 1.5-2.5NL / mim·ton of steel; control the pressure at 0.15MPa; Nitrogen content is required to set the nitrogen blowing time, calculated according to 3.5-4.2ppm / min per ton of steel;

[0013] 3. After the VD is broken, set the appropriate nitrogen blowing time, flow rate and pressure to make the nitrogen content stable and controllable: the nitrogen blowing flow rate ...

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Abstract

The invention relates to a method for controlling the nitrogen content in N80 steel. The method comprises the following steps: firstly, the LF slag smelting is stabilized and the deoxidation technology is perfected so that the weight and the components of the molten slag are controllable and the nitrogen flushing state during the process is stable; secondly, the proper nitrogen flushing flow, pressure and time are set in the VD packing process so that the nitrogen content after emptying is stable; and thirdly, the proper nitrogen flushing time, flow and pressure are set after the VD emptying so that the nitrogen content is stable and controllable. The method performs improvement to the non-quenching and tempering way, effectively controls the nitrogen content in the N80 level steel by taking measures, not only has low cost, but also effectively reduces the surface cracks of the casting billet and improves the quality of products.

Description

technical field [0001] The invention relates to a method for controlling nitrogen content in N80 steel. Background technique [0002] At present, domestic production of N80 oil pipe steel is generally produced by quenching and tempering treatment. This production method has many procedures and high cost. However, the non-quenching and tempering method is used for production, that is, it is controlled by adding vanadium-nitrogen alloy or ferrovanadium plus nitrogen blowing process, and the vanadium and nitrogen content in the steel must be guaranteed. The cost of the former is high, and the alloy yield is not stable; although the cost of the latter is low, but the process of blowing nitrogen into the ladle is adopted, the control of nitrogen content is unstable, because N80 steel requires high content of [N] and [V] , resulting in the precipitation of [VNC] compound on the grain boundary, thereby destroying the continuity of the grain boundary, causing the grain boundary to ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21C7/076C21C7/072
CPCY02P10/20
Inventor 杨辉曹维华原丽君祖晓风仉勇
Owner ANGANG STEEL CO LTD
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