Austenitic stainless steel continuous casting method for improving surface defects

A technology of austenitic and stainless steel, applied in the field of continuous casting of austenitic stainless steel, can solve the problems of inability to judge, the actual yield reduces grinding costs, etc., and achieves the effect of improving defects and reducing black belt defects.

Active Publication Date: 2018-03-13
POSCO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the prior art, since the surface of the slab is observed with the naked eye after continuous casting, it is impossible to judge whether carburization has occurred with the naked eye. Therefore, even if the defect rate is low, the entire surface will be ground or found in the subsequent process. Defects are ground to remove
In this case, although the quality of the final product can be improved, there is a disadvantage that the yield rate will decrease and additional grinding costs will be incurred. Therefore, it is urgent to produce good products by omitting surface grinding as much as possible.

Method used

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  • Austenitic stainless steel continuous casting method for improving surface defects
  • Austenitic stainless steel continuous casting method for improving surface defects
  • Austenitic stainless steel continuous casting method for improving surface defects

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1-6

[0080] During the continuous casting of austenitic stainless steel, the continuous casting slabs were manufactured according to the conditions in the following Table 1, and the slag and slag lumps in the mold were confirmed during continuous casting, and the presence of defects on the surface of the slabs was confirmed visually, and the display in Table 2 below.

[0081] 【Table 1】

[0082]

[0083]

[0084] 【Table 2】

[0085]

[0086] Referring to Table 1 and Table 2, when the casting temperature superheat ΔT is in the range of 20 to 40°, and the discharge angle of the submerged nozzle is from 0° to 15° downward, the thickness of the center and edge of the slag layer The difference is -3 to 6mm, less than 10mm, and when the width ratio of the slag block is properly controlled below 110%, there is no abnormal structure on the surface layer, and no black band defect occurs on the hot-rolled product.

[0087] It can be judged that in the section where the degree of super...

Embodiment 7-9

[0100] When continuous casting of austenitic stainless steel, according to the conditions in the following Table 3, set the area where the mold powder is not put in, set the superheat of the casting temperature to 50°C, and set the discharge angle of the submerged nozzle to 0°, so that Continuous casting slabs were produced, and whether defects occurred on the surface of the slabs was judged with the naked eye, and the results are shown in Table 3.

[0101] 【table 3】

[0102]

[0103] As shown in Comparative Examples 10 and 11, it can be seen that the non-introduced area of ​​mold flux is 10% or less. If it becomes too small, a sufficient slag layer cannot be secured, and slab surface defects occur. As shown in Comparative Example 12, it can be seen that protection If the area where the slag is not injected is too large, the meniscus surface layer of molten steel is excessively cooled, and slab surface layer defects occur.

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PUM

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Abstract

The invention discloses an austenitic stainless steel continuous casting method for improving surface defects. The austenitic stainless steel continuous casting method includes a step of throwing protection casting slag into a moltensteel mold containing the austenitic stainless steel. Thickness differences between parts of a slag layer formed on the molten steel are smaller than 10mm. As a result, after the molten steel temperature is regulated through deoxidization and fine refining of the austenitic stainless steel, the temperature of the molten water which is injected from a steel ladle to a tundish and an ejection flow discharged from the tundish to the casting mold are controlled in order to control thickness of parts of the slag. Protection slag investment is optimized in order toreduce the mixture of the protection slag into a surface of a casting blank and reduce occurrence of black strip defects so as to improve the defects of the surface of the austenitic stainless steel continuous casting blank.

Description

technical field [0001] The present invention relates to a continuous casting method of austenitic stainless steel, and in more detail, relates to a continuous casting method of austenitic stainless steel with improved surface defects. Background technique [0002] 304 steel among austenitic stainless steels is produced into general-purpose steel and ordinary steel, and is used for kitchen utensils, household items, building materials, etc. because of its excellent corrosion resistance, heat resistance, and mechanical properties. [0003] Among them, when the above-mentioned 304 steel is produced by continuous casting, if the carbon content in the mold flux used in the continuous casting process is not properly controlled, it frequently occurs in the cold-rolled coil of the austenitic stainless steel Black band defects such as black band defects. [0004] The black belt defect of austenitic stainless steel mainly appears in the center of the slab. Since the temperature of t...

Claims

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Application Information

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IPC IPC(8): B22D11/111B22D11/18
CPCB22D11/002B22D11/111B22D11/181B22D11/103B22D11/11
Inventor 金知俊
Owner POSCO
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