A kind of vacuum induction furnace smelting rapid denitrification method

A vacuum induction furnace and denitrification technology, applied in furnaces, electric furnaces, furnace types, etc., can solve problems such as the decrease of working vacuum, the number of oxide inclusions and slag, and the effect of denitrification, and achieve the effect of small erosion

Active Publication Date: 2020-07-21
JIANGSU JICUI ADVANCED METAL MATERIAL RES INST CO LTD
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Problems solved by technology

The shortcomings of these two methods are that the raw material and manufacturing cost of the material are significantly increased, and the second is that the long-term standing will lead to intensified erosion of the refractory lining, which will increase the number of oxide inclusions and slag inclusions, and reduce the purity level of the material. The third is that N The content decline is limited, and the N content is difficult to be lower than 15ppm
CN106868345A mentions the use of ultra-high temperature refining to remove nitrogen, but ultra-high temperature operation will lead to intensified erosion of the furnace lining and increase the number of inclusions and slag inclusions
CN105238934A and CN106222460B mention that Nb, Al, Ti and other elements with strong affinity with N are added in the later stage of smelting, which is a common practice in industrial production, but it does not effectively solve the problem of N in the main raw material in the early stage
CN102703794B, CN102719686B and CN103114172A all mention the method of assembling a breathable brick in the middle of the bottom of the vacuum induction furnace, and generating bubbles to denitrify by blowing argon gas at the bottom. Nitrogen method, but there are two deficiencies. One is that due to the characteristics of the vacuum induction melting pool flowing downward from the middle and then upward from both sides of the bottom, the position of the breathable brick in the middle will inhibit the effective floating of argon bubbles and affect Second, according to Siewert's law, the solubility of N is also related to the degree of vacuum. Due to the release of O, the degree of vacuum during the smelting and refining periods will decrease significantly. Therefore, effective means must be taken to reduce the degree of melting Pool O content

Method used

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  • A kind of vacuum induction furnace smelting rapid denitrification method

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Experimental program
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Effect test

Embodiment 1

[0016] Turn on the argon gas switch, check whether the two gas permeable bricks at the bottom of the crucible are normal, if not, replace the smelting preparation stage, estimate according to the oxygen content of the main raw materials such as electrolytic nickel plate, industrial pure iron, medium carbon ferrochrome, etc., according to the mass fraction of 50% The ratio is mixed with carbon powder and placed on the bottom of the crucible. Close the furnace cover and start vacuuming until the absolute vacuum reaches about 10 -2 Pa, and the static air leakage rate does not exceed 300Pa.L / s, if it is abnormal, it needs to be checked and dealt with. When electrified and melted, sufficient carbon-oxygen reaction helps to remove part of N. After the charge is completely melted, turn on the bottom blowing argon switch and adjust the flow rate or pressure, and observe that there are obvious bubbles escaping from the surface of the molten pool, and the time is 30 minutes. After the...

Embodiment 2

[0018] Turn on the argon gas switch, check whether the two gas permeable bricks at the bottom of the crucible are normal, and replace them if they are abnormal.

[0019] In the smelting preparation stage, according to the estimation of the oxygen content of the main raw materials such as industrial pure iron, electrolytic nickel plate, ferrosilicon, etc., the corresponding carbon powder is mixed in the proportion of 150% by mass fraction and placed at the bottom of the crucible. Close the furnace cover and start vacuuming until the absolute vacuum reaches about 10 -2 Pa, and the static air leakage rate does not exceed 300Pa.L / s, if it is abnormal, it needs to be checked and dealt with. When electrified and melted, sufficient carbon-oxygen reaction helps to remove part of N. After the charge is completely melted, turn on the bottom blowing argon switch and adjust the flow rate or pressure, and observe that there are obvious bubbles escaping from the surface of the molten pool,...

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Abstract

The invention discloses a fast denitrifying method for melting of a vacuum induction furnace. The fast denitrifying method has the beneficial effects that the removal rate of N content in high-performance alloys can be 70% or above, the lowest removal rate is 10ppm or below, the increased smelting time is 60min at most, and the corrosion influence on a furnace liner is small.

Description

technical field [0001] The invention belongs to the field of special metallurgy, and specifically relates to a nitrogen removal process for special steel and high-performance alloys (corrosion-resistant alloys and high-temperature alloys). Background technique [0002] High-performance alloys mainly refer to high-strength steels and high-temperature corrosion-resistant alloys used in aerospace, nuclear power, energy and chemical industries, etc., usually using Ti, Al, Nb, etc. as precipitation strengthening elements to improve service performance. However, N has a high affinity with Ti, Al, and Nb, and it is easy to form inclusions such as TiN, AlN, and NbN. These inclusions have high hardness, high melting point, and irregular shape, and are difficult to remove even in the subsequent remelting process. Therefore, high Performance Alloys have very strict requirements on the control of N content during vacuum induction melting. [0003] At present, there are mainly two metho...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21C5/52C21C7/04
CPCC21C5/5241C21C7/04
Inventor 沈海军张丕军程兴德
Owner JIANGSU JICUI ADVANCED METAL MATERIAL RES INST CO LTD
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