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Method for refining rare earth inclusions in steel through magnesium pretreatment

A pretreatment and inclusion technology, applied in the field of iron and steel metallurgy, can solve the problems of large size of rare earth inclusions, achieve the effects of reducing dissolved oxygen content, improving steel performance, and wide application range

Pending Publication Date: 2022-03-01
NORTHEASTERN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The purpose of the present invention is to provide a method for magnesium pretreatment to refine rare earth inclusions in steel, and to solve the technical problem of large rare earth inclusions when aluminum deoxidized steel is treated with rare earth

Method used

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  • Method for refining rare earth inclusions in steel through magnesium pretreatment
  • Method for refining rare earth inclusions in steel through magnesium pretreatment
  • Method for refining rare earth inclusions in steel through magnesium pretreatment

Examples

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Embodiment 1

[0032] S32750 super duplex stainless steel is smelted by "EAF→AOD→LF→die casting" process, and LF is the last refining process. The amount of molten steel is 30t. The chemical composition of S32750 super duplex stainless steel is shown in Table 1.

[0033] Table 1S32750 super duplex stainless steel chemical composition (wt.%)

[0034]

[0035] This example provides a method for magnesium pretreatment to refine rare earth inclusions in steel. For S32750 super duplex stainless steel, the specific process flow is as follows:

[0036] (1) EAF is used to melt S32750 super duplex stainless steel, and AOD is used to decarburize, desulfurize and alloy it. The above operations are all carried out according to conventional processes. After entering the LF station, the tempering and slag adjustment operations are carried out first. The composition of the refining slag is shown in Table 2, which meets the requirements of white slag refining. Afterwards, the aluminum deoxidation oper...

Embodiment 3

[0047] The process of "BOF→LF→RH→Continuous Casting" is used to smelt H13 die steel. RH is the last refining process, and the amount of molten steel is 120t. The chemical composition of H13 die steel is shown in Table 4.

[0048] Table 4H13 Die Steel Chemical Composition (wt.%)

[0049]

[0050] This embodiment provides a method for magnesium pretreatment to refine rare earth inclusions in steel. For H13 die steel, the specific process flow is as follows:

[0051] (1) BOF is used to decarburize and alloy H13 steel, and LF is used to adjust the temperature, slag and aluminum deoxidation of H13 steel. The above operations are all carried out according to the conventional process. Among them, after the aluminum deoxidation operation, the bottom blowing argon flow rate was adjusted to 1.5NL / (min·t), and soft blowing was performed at this argon flow rate for 15 minutes. Table 5 shows the composition of LF refining slag, which meets the requirements of white slag refining. Aft...

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Abstract

The invention relates to the technical field of ferrous metallurgy, in particular to a method for refining rare earth inclusions in steel through magnesium pretreatment, and solves the technical problem that the rare earth inclusions are large in size when aluminum deoxidized steel is subjected to rare earth treatment. After refining slag components and the content of aluminum, oxygen and sulfur in molten steel reach a control target, magnesium pretreatment is firstly carried out to modify large-size Al2O3 inclusions into fine and dispersed MgO inclusions, then rare earth treatment is carried out, the fine and dispersed MgO inclusions are converted to obtain rare earth inclusions, and the size of the rare earth inclusions is obviously refined compared with that of magnesium-free pretreatment. And meanwhile, the density of MgO inclusions is smaller than that of Al2O3 inclusions, and the MgO inclusions can float upwards and be discharged more easily according to the Stokes law, so that the cleanliness of the steel can be further improved by adopting magnesium pretreatment. The method is easy to operate, efficient, safe, low in steel grade limitation, suitable for refining processes such as LF, VD and RH and wide in application range.

Description

technical field [0001] The invention relates to the technical field of iron and steel metallurgy, in particular to a method for magnesium pretreatment to refine rare earth inclusions in steel. Background technique [0002] Rare earth treatment can significantly improve the performance of steel. Compared with conventional deoxidizers such as aluminum, silicon, and manganese, rare earths have stronger affinity with harmful elements such as oxygen, sulfur, and phosphorus, so rare earth treatment is widely used in super stainless steel, tool and die steel, structural steel, pipeline steel, and weathering steel etc. to achieve deep deoxidation and deep desulfurization, denatured MnS inclusions, refinement of steel solidification structure, refinement of liquid precipitation carbides, etc., and then significantly improve the comprehensive properties of steel such as mechanical properties, corrosion resistance, and oxidation resistance. [0003] However, the rare earth oxygen sulf...

Claims

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Application Information

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IPC IPC(8): C21C7/00C21C7/072
CPCC21C7/0006C21C7/0056C21C7/072Y02P10/20
Inventor 姜周华郑立春彭博李花兵张树才晏百强王飞宇
Owner NORTHEASTERN UNIV
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