A production process for increasing nitrogen content in vanadium-containing threaded steel

Abstract

The application provides a production process for increasing nitrogen content in vanadium-containing threaded steel, and comprises the following process steps: adjusting the charging system of a converter, and producing according to 880 kg / t of molten iron consumption; controlling the end point temperature of the converter at 1600-1630 DEG C, and controlling the end point carbon of the converter at 0.06%-0.10%; adjusting the bottom continuous blowing mode of the converter, and injecting nitrogen gas in the whole process, the nitrogen blowing intensity before the 60% oxygen step is 0.077 Nm 3 / t·min, the nitrogen blowing intensity from the 60% oxygen step to the end of blowing is 0.054 Nm 3 / t·min; improving the supplementary blowing mode of the converter, after the end point stage of the converter is reversed, nitrogen gas is blown into the converter by using an oxygen lance for 1.5 minutes, and then the tapping operation is carried out; optimizing the power transmission operation of the LF refining furnace; and adjusting the use of silicon ferro-nitride alloy of the LF refining furnace. The application can increase the nitrogen content in the molten steel, and the proportion of the produced vanadium-containing threaded steel product with the nitrogen content controlled at 0.012%-0.018% is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy, and in particular to a production process for increasing the nitrogen content in vanadium-containing threaded steel. Background Art

[0002] HRB500E series seismic rebar is favored for its high strength and excellent performance, and is widely used in buildings requiring high levels of earthquake resistance. Typically, trace amounts of the element vanadium are added to steel to form carbides and nitrides for precipitation strengthening. However, nitrides in steel are more stable than carbides, forming a finer, more evenly distributed strengthening phase, resulting in a more pronounced strengthening effect. Therefore, the nitrogen content of HRB500E series products must be controlled between 0.012% and 0.018%.

[0003] In conventional production processes, vanadium-nitrogen alloys are typically added to molten steel to increase its vanadium and nitrogen contents. However, because vanadium yields are more stable than nitrogen yields, this can result in nitrogen levels falling below 0.012% even when the vanadium content meets the steel grade's internal control requirements. This can potentially fail to meet the steel's mechanical property requirements. On the other hand, increasing the amount of vanadium-nitrogen alloy to meet nitrogen control requirements can easily cause the vanadium content to exceed the control range, leading to steel scrapping. Furthermore, vanadium-nitrogen alloys are expensive metals, which can increase production costs.

[0004] Therefore, we need to find a way to increase the nitrogen content in molten steel in the process flow of converter, LF refining furnace, etc., and stably enhance the nitrogen content in molten steel, so as to ensure that the mechanical properties of HRB500E series products meet the standards. Summary of the Invention

[0005] The object of the present invention is to provide a production process for increasing the nitrogen content in vanadium-containing threaded steel, so as to solve some problems existing in the prior art.

[0006] To achieve the above object, the present invention adopts the following technical solution: a production process for increasing the nitrogen content in vanadium-containing threaded steel, specifically comprising the following process steps:

[0007] Step 1: Adjust the converter charging system and organize production based on a molten iron consumption of 880kg / t to facilitate converter endpoint control and promote nitrogen absorption by molten steel;

[0008] Step 2: Control the converter endpoint temperature at 1600-1630°C and the converter endpoint carbon content at 0.06%-0.10%;

[0009] Step 3: Adjust the continuous blowing mode at the bottom of the converter and inject nitrogen during the entire process. The nitrogen blowing intensity before the 60% oxygen step is 0.077Nm3 / t·min, 60% oxygen step to the end of blowing, nitrogen blowing intensity is 0.054Nm 3 / t·min;

[0010] Step 4: Improve the converter re-blowing mode. After pouring the converter at the final stage, use an oxygen lance to blow nitrogen into the furnace for 1.5 minutes before tapping.

[0011] Step 5: Optimize the power supply operation of the LF refining furnace: When the LF furnace enters the station, open the bypass equipment, adjust the bottom argon flow to 500-800NL / min, and adjust the transformer current to 30000A to perform 4-5 power supply operations to promote nitrogen absorption by molten steel;

[0012] Step 6: Adjust the use of ferrosilicon nitride in the LF refining furnace: After the LF refining furnace has refined the same components, add an appropriate amount of ferrosilicon nitride to the ladle according to the standard of increasing nitrogen by 0.0005% per 10kg of ferrosilicon nitride, and perform power heating treatment to promote nitrogen increase in the molten steel using ferrosilicon nitride.

[0013] In step 4, the nitrogen flow rate during the oxygen lance blowing process is controlled at 28500Nm 3 / h, and the oxygen lance position is maintained at 2.5m.

[0014] The above technical solution has the following beneficial effects compared with the existing technology: it can increase the nitrogen content in molten steel, so that the nitrogen content of the produced vanadium-containing threaded steel products is controlled at a ratio of 0.012%-0.018%, which is greatly improved. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0016] In view of the problems existing in the prior art, the present invention provides a production process for increasing the nitrogen content in vanadium-containing threaded steel. The present invention is described in detail below.

[0017] The technical solution adopted in this specific embodiment is: a production process for increasing the nitrogen content in vanadium-containing threaded steel, which specifically includes the following process steps:

[0018] Step 1: Optimize the converter charging system and organize production based on a hot metal consumption of 880kg / t to facilitate converter endpoint control and promote nitrogen absorption by molten steel. Specifically, a production method with a hot metal consumption of 880kg / t can be adopted. By controlling the hot metal consumption, the converter endpoint can be kept stable and accurate, thereby promoting nitrogen absorption by molten steel.

[0019] Step 2: Optimize the converter endpoint control targets: the converter endpoint temperature is controlled at 1600-1630°C, and the converter endpoint carbon is controlled at 0.06%-0.10%. By controlling the converter endpoint temperature and carbon, the nitrogen content in the molten steel can be effectively controlled to ensure the quality of the molten steel.

[0020] Step 3: Optimize the bottom blowing mode of the converter: Blow nitrogen into the converter bottom blowing process, and the nitrogen blowing intensity before the 60% oxygen step is 0.077Nm 3 / t·min, 60% oxygen step to the end of blowing, nitrogen blowing intensity is 0.054Nm 3 By adjusting the nitrogen flow rate in the converter bottom blowing mode, the nitrogen content in the molten steel can be controlled, ensuring the continuity and stability of production;

[0021] Step 4: Optimize the converter re-blowing mode: After the final furnace is poured, use an oxygen lance to blow nitrogen into the furnace for 1.5 minutes before tapping. The nitrogen flow rate during the nitrogen blowing process is 28500 Nm 3 / h, and the oxygen lance position is controlled at 2.5m. By using the oxygen lance to blow nitrogen into the furnace after the final pouring, the nitrogen content in the molten steel can be increased and the production efficiency can be improved;

[0022] Step 5: Optimize the power supply operation of the LF refining furnace: After the LF furnace enters the station, open the bypass, adjust the bottom argon flow rate to 500-800NL / min, adjust the transformer current to 30,000A, and supply power 4-5 times to promote nitrogen absorption by the molten steel. By adjusting the power supply parameters of the LF refining furnace, the absorption of nitrogen by the molten steel can be promoted;

[0023] Step 6: Optimize the use of ferrosilicon nitride in the LF refining furnace: After the LF refining furnace has refined the same components, ferrosilicon nitride is added to the ladle based on the nitrogen content of the molten steel, at a rate of 0.0005% per 10kg of ferrosilicon nitride. Then, power is supplied for heating, using the ferrosilicon nitride to promote nitrogen addition in the molten steel. Adding an appropriate amount of ferrosilicon nitride to the ladle promotes nitrogen absorption in the molten steel.

[0024] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A production process for increasing the nitrogen content in vanadium-containing threaded steel, characterized in that: The specific process steps include: Step 1: Adjust the converter charging system and organize production based on a molten iron consumption of 880kg / t to facilitate converter endpoint control and promote nitrogen absorption by molten steel; Step 2: Control the converter endpoint temperature at 1600-1630°C and the converter endpoint carbon content at 0.06%-0.10%; Step 3: Adjust the continuous blowing mode at the bottom of the converter and inject nitrogen during the entire process. The nitrogen blowing intensity before the 60% oxygen step is 0.077Nm 3 / t·min, 60% oxygen step to the end of blowing, nitrogen blowing intensity is 0.054Nm 3 / t·min; Step 4: Improve the converter re-blowing mode. After pouring the converter at the final stage, use an oxygen lance to blow nitrogen into the furnace for 1.5 minutes before tapping. Step 5: Optimize the power supply operation of the LF refining furnace: When the LF furnace enters the station, open the bypass equipment, adjust the bottom argon flow to 500-800NL / min, and adjust the transformer current to 30000A to perform 4-5 power supply operations to promote nitrogen absorption by molten steel; Step 6: Adjust the use of ferrosilicon nitride in the LF refining furnace: After the LF refining furnace has refined the same components, add an appropriate amount of ferrosilicon nitride to the ladle according to the standard of increasing nitrogen by 0.0005% per 10kg of ferrosilicon nitride, and perform power heating treatment to promote nitrogen increase in the molten steel using ferrosilicon nitride.

2. The production process for increasing the nitrogen content in vanadium-containing threaded steel according to claim 1, characterized in that: In step 4, the nitrogen flow rate during the oxygen lance blowing process is controlled at 28500Nm 3 / h, and the oxygen lance position is maintained at 2.5m.