Method for increasing nitrogen in refining furnace

A refining furnace and nitrogen-increasing technology, applied in the field of nitrogen-increasing in refining furnaces, can solve the problems of increasing the production cost per ton of steel, reducing the purity of molten steel, secondary oxidation of molten steel, etc., so as to reduce pollution, improve the purity of molten steel, avoid The effect of secondary oxidation

Active Publication Date: 2009-12-30
SHANXI TAIGANG STAINLESS STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantages of this method are: first, the impurities in the nitrided alloy will enter the steel and cause pollution to the steel; second, it will increase the production cost per ton of steel; third, it will easily cause secondary oxidation of molten steel, which will reduce the purity of molten steel

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] This embodiment is carried out on a 90-ton double-station VOD furnace. Two bottom-blown gas supply devices are installed at the bottom of the ladle used. The maximum single-bottom gas supply flow rate is 600L / min, and the highest vacuum degree of VOD is 67Pa.

[0035] The smelted steel type is 0Cr18Ni9, the liquidus temperature is 1460°C, and the mass percentage distribution of the chemical composition of the finished steel type is shown in Table 2:

[0036] Table 2

[0037] Yuan

white

C

Si

mn

P

S

Cr

Ni

N

mark

allow

≤0.07

≤

1.00

≤2.00

≤

0.035

≤

0.030

18.00-19.

00

8.00-11.0

0

≤0.100

head

mark

0.05

0.50

1.20

≤

0.030

≤

0.003

18.10

8.05 ...

Embodiment 2

[0066] This example is carried out on a 90-ton double-station VD. Two bottom blowing air supply devices are installed at the bottom of the ladle used. The single bottom air supply flow rate is up to 600L / min, and the highest vacuum degree of VD is 67Pa. The smelted steel grade S30432 has a liquidus temperature of 1440°C, and the mass percentage distribution of the chemical composition of the finished steel grade is shown in Table 3:

[0067] table 3

[0068] the element

C

Si

mn

P

S

N

standard

0.07-0.13

≤0.30

≤1.00

≤0.030

≤0.025

0.050-0.120

Target

0.075

0.20

0.80

≤0.015

≤0.001

0.110

the element

Cr

Ni

Mo

co

Cu

Nb

standard

17.00-19.00

7.50-10.50

-

-

2.50-3.50

0.20-0.60

Target

18.50

9.00

0.31

0.13

3.00

0.50

[0069] Note: After ...

Embodiment 3

[0083] This example is carried out on a 90-ton double-station VD. Two bottom blowing air supply devices are installed at the bottom of the ladle used. The single bottom air supply flow rate is up to 600L / min, and the highest vacuum degree of VD is 67Pa.

[0084] The smelted steel type T91 has a liquidus temperature of 1505°C, and the mass percentage distribution of the chemical composition of the finished steel type is shown in Table 4:

[0085] the element

C

Si

mn

P

S

Cr

Mo

Nb

V

Al

N

standard

0.08

-0.12

0.20

-0.50

0.30

-0.60

≤

0.020

≤

0.010

8.00

-9.50

0.85

-1.05

0.06

-0.10

0.18

-0.25

≤

0.015

0.030

-0.070

Target

0.09

0.30

0.40

≤

0.012

≤

0.003

8.30

...

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PUM

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Abstract

The invention provides a method for increasing nitrogen in a refining furnace. The steps of the method is characterized by: (1) blowing in nitrogen with the pressure of not less than 0.5MPa and with the bottom blowing total flow of not less than 500L/min after the completeness of VOD refining furnace reduction or after the completeness of dehydrogenation in VD refining furnace; and (2) calculating the time of nitrogen increasing: a. figuring out the increased nitrogen required by liquid steel: delta N=[N]-[N][before]; wherein, delta N is the increased nitrogen required by liquid steel (%), [N] is the target nitrogen content which the liquid steel needs to achieve after the completeness of each steel ball processing (%), [N][before] is nitrogen content in liquid steel before increasing nitrogen (%); and b. figuring out the time to increase nitrogen: in the nitrogen increasing process, the temperatrue drop of liquid steel is calculated by rendering that y equals to 1.2 DEG C/min-2.0 DEG C/min; the formula is as follows: delta N=1.25*Q*t*10<-188/(T-yt+273)-1.25+0.51gP-1gf>; wherein, Q is the bottom blow total flow (L/min), t is the time to increase nitrogen (min), T is the temperature of liquid steel before increasing nitrogen (DEG C), P is vacuum degree in the furnace (10<5>Pa), and y is the temperature drop of liquid steel in the process of increasing nitrogen (DEG C/min). The method for increasing nitrogen in the refining furnace has low cost.

Description

technical field [0001] The invention relates to a method for increasing nitrogen in a refining furnace, specifically a method for increasing nitrogen in a vacuum after the reduction of the VOD refining furnace or the dehydrogenation of the VD refining furnace is completed. Background technique [0002] Adding nitrogen as an alloying element to steel can stabilize austenite and improve the mechanical properties and corrosion resistance of steel. For this reason, some stainless steels and carbon steels require a certain nitrogen content in the steel. Now the method of increasing the nitrogen content in steel in VOD or VD refining furnace is: after the reduction of VOD refining furnace or the dehydrogenation of VD refining furnace is completed, nitrogen alloy is added to molten steel under the atmosphere for nitrogen alloying. The disadvantages of this method are: first, the impurities in the nitrided alloy will enter the steel and pollute the steel; second, it will increase t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C7/00C21C7/072C21C7/10
Inventor 张增武
Owner SHANXI TAIGANG STAINLESS STEEL CO LTD
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