Method for producing high nitrogen steel by duplex melting process of pressurized ladle refining and pressurized electroslag remelting

Patent metadata

Field	Value
Publication number	US-11732337-B2
Application number	US-202117325619-A
Country	US
Kind code	B2
Filing date	May 20, 2021
Priority date	Jan 15, 2021
Publication date	Aug 22, 2023
Grant date	Aug 22, 2023

Abstract

The present disclosure provides a method for producing a high nitrogen steel by a duplex melting process of a pressurized ladle refining and a pressurized electroslag remelting, which relates to the technical field of high nitrogen steel melting. In the present disclosure, the molten steel is subjected in sequence to a nitrogen alloying, a deep deoxidation and a deep desulfurization by adding a nickel-magnesium alloy and rare earth in the pressurized ladle furnace, and a combination of a blowing nitrogen from the bottom of the pressurized ladle and a pressurized nitriding at the interface of gas and the molten steel is used to achieve a high-efficiency nitrogen alloying, a uniform nitrogen distribution, and a decreased impurity content in the ingot; then the ingot is subjected to a pressurized electroslag remelting to obtain a high nitrogen steel.

First claim

What is claimed is:

1. A method for producing a high nitrogen steel by a duplex melting process of pressurized ladle refining and a pressurized electroslag remelting, comprising the following steps:
(1) subjecting a molten steel to a nitrogen alloying in a pressurized ladle furnace to obtain a nitrogen-alloyed molten steel,
then subjecting the nitrogen-alloyed molten steel to a deep deoxidation to obtain a deeply deoxidized product,
subjecting the deeply deoxidized product to a deep desulfurization to obtain a deeply desulfurized product, and
finally casting the deeply desulfurized product, to obtain a high nitrogen steel ingot,
wherein the nitrogen alloying comprises blowing nitrogen from the bottom of the pressurized ladle and nitriding at the interface of gas and the molten steel under pressure; and the deep deoxidation and deep desulfurization are achieved by adding a nickel-magnesium alloy and rare earth to the nitrogen-alloyed molten steel; and
(2) subjecting the high nitrogen steel ingot obtained in step (1) to a pressurized electroslag remelting, to obtain a high nitrogen steel electroslag remelting ingot;
wherein a gas nitriding pressure p 1 during the nitriding at the interface of gas and the molten steel in step (1) is calculated according to Formula I:

1
⁢

g
⁡

[

%
⁢

⁢
N

]

=

1
2

⁢
1
⁢

g
⁡

(

p
1

⁢

/

⁢

p
θ

)

-

188
T

-
1.17
-

{

(

3280
T

-
0.75

)

⁢

(

0.13
⁡

[

%
⁢

⁢
N

]

+

0.118
⁡

[

%
⁢

⁢
C

]

+

0.043
⁡

[

%
⁢

⁢
Si

]

+

0.011
⁡

[

%
⁢

⁢
Ni

]

+

3.5
×

10

-
5

⁡

[

%
⁢

Assignees

• Univ Northeastern

Inventors

• Li Huabing
• Jiang Zhouhua
• Feng Hao
• Xia Lingfeng
• Zhu Hongchun
• Zhang Shucai
• Jiao Weichao

Classifications

• C22C38/001 Primary

  containing N · CPC title

• C21C7/0075

  Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle · CPC title

• C21D6/002

  containing Cr (C21D6/004 takes precedence) · CPC title

• C21D6/005

  containing Mn · CPC title

• C22B9/18

  Electroslag remelting {(electroslag casting B22D23/10)} · CPC title