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Smelting method for reducing edge crack occurrence rate of 45 steel plate

A smelting method and technology of occurrence rate, which is applied in the smelting field of reducing the incidence rate of 45 steel plate edge cracks, can solve the problems of restricting output and quality, increasing crack sensitivity, reducing steel thermoplasticity, etc., and achieves low production cost, simple operation, and easy The effect of control

Active Publication Date: 2020-11-06
WUHAN IRON & STEEL GRP ECHENG IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Edge cracks are one of the main quality defects of 45 steel medium and thick plates. The edge cracks of 45 steel are mainly caused by subcutaneous air bubbles and transverse cracks at the corners. The analysis shows that the corner cracks of the slab are directly related to the aluminum and nitrogen in the steel. It has an impact on thermoplasticity, especially when aluminum and nitrogen are present at the same time. When the produced AlN precipitates at the austenite grain boundary, it will reduce the thermoplasticity of the steel and increase the crack sensitivity
At present, edge cracking of 45 steel plates is a common technical problem faced by iron and steel enterprises, which will restrict the improvement of output and quality, and affect the profitability of enterprises. Solving the quality defects of 45 steel plate edge cracks requires the support of new technologies

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] A kind of smelting method of reducing the occurrence rate of edge cracking of 45 steel plates of the present embodiment comprises the following steps:

[0034] (1) The top-bottom combined blowing converter is used for smelting, the total loading of molten iron and scrap steel is 160t, and the ratio of molten iron and scrap steel is 4.5:1, of which the amount of molten iron is 129t and the amount of scrap steel is 31t;

[0035] (2) Argon is used as the bottom blowing gas in the blowing process of the top-bottom combined blowing converter, and the flow rate of the argon gas (the flow rate of the bottom blowing of each branch pipe is controlled at 65m in the early stage) 3 / h under standard state, mid-term control at 35m 3 / h standard state, the late control is 70m 3 / h standard state);

[0036] (3) The C content at the end point of the converter is 0.15%, and the steel is tapped directly without supplementary blowing. The carbon at the end point and the number of spot blo...

Embodiment 2

[0046] A kind of smelting method of reducing the occurrence rate of edge cracking of 45 steel plates of the present embodiment comprises the following steps:

[0047] (1) The top-bottom combined blowing converter is used for smelting, the total loading of molten iron and scrap steel is 160t, and the ratio of molten iron and scrap steel is 4.8:1, of which the amount of molten iron is 129t and the amount of scrap steel is 27.6t;

[0048] (2) Argon is used as the bottom blowing gas in the blowing process of the top-bottom compound blowing converter, and the flow rate of argon gas (the flow rate of the bottom blowing of each branch pipe is controlled at 60m in the early stage) 3 In / h standard state, the mid-term control is at 40m 3 / h standard state, the late control is 65m 3 / h standard state);

[0049] (3) The C content at the end point of the converter is 0.13%, and the steel is directly tapped without supplementary blowing. The end point carbon and the number of spot blowin...

Embodiment 3

[0059] A kind of smelting method of reducing the occurrence rate of edge cracking of 45 steel plates of the present embodiment comprises the following steps:

[0060] (1) The top-bottom combined blowing converter is used for smelting, the total loading of molten iron and scrap steel is 160t, and the ratio of molten iron and scrap steel is 5.0:1, of which the amount of molten iron is 133.3t and the amount of scrap steel is 26.7t;

[0061] (2) Argon is used as the bottom blowing gas in the blowing process of the top-bottom combined blowing converter, and the flow rate of the argon gas (the flow rate of the bottom blowing of each branch pipe is controlled at 70m in the early stage) 3 / h under standard state, mid-term control at 30m 3 / h standard state, the late control is 67.5m 3 / h standard state);

[0062] (3) The C content at the end point of the converter is 0.14%, and the steel is directly tapped without supplementary blowing. The end point carbon and the number of spot bl...

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PUM

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Abstract

The invention discloses a smelting method for reducing the edge crack occurrence rate of a 45 steel plate. The smelting method comprises the following steps that (1) the hot metal ratio is increased,and hot metal and scrap steel are added according to the ratio of 4.5-5 to 1; (2) argon is blown from the bottom in the whole top-bottom combined blowing converter blowing process; (3) a weak deoxidation process is carried out in a converter tapping process; (4) low-aluminum-consumption control is carried out in a ladle furnace refining process; (5) a steelmaking process is adjusted by utilizing the fact that the temperature of TiN precipitated by reaction of titanium with nitrogen is higher than the temperature of reaction of aluminum with the nitrogen, and ferrotitanium is added for nitrogenfixation in the later stage of refining so as to reduce combination between the nitrogen and the aluminum; (6) the content of the N and the content of the Al in steel are controlled; (7) a small-taper crystallizer is adopted, and the cooling effect of the crystallizer is optimized; and (8) the continuous casting of different section specifications is properly accelerated, the staying time of a casting blank in a secondary cooling section is shortened, the secondary cooling water amount is properly reduced, the corner temperature of the casting blank is increased, and a brittle zone with the temperature range of 700 - 900 DEG C is avoided. Through the process control, the purpose of reducing the edge crack occurrence rate of the 45 steel plate is achieved.

Description

technical field [0001] The invention relates to the technical field of iron and steel smelting, in particular to a smelting method for reducing the occurrence rate of edge cracks in 45 steel plates. Background technique [0002] The cracking caused by the tensile stress on the side of the steel plate during the pressing process is called edge cracking. The depth of the edge cracking can be detected by ultrasonic flaw detection. Once the steel cracks, it is irreparable and the width will be insufficient. Edge cracks are one of the main quality defects of 45 steel medium and thick plates. The edge cracks of 45 steel are mainly caused by subcutaneous air bubbles and transverse cracks at the corners. The analysis shows that the corner cracks of the slab are directly related to the aluminum and nitrogen in the steel. It has an impact on thermoplasticity, especially when aluminum and nitrogen exist at the same time. When the produced AlN precipitates at the austenite grain boundar...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/14C21C5/35C21C7/06C21C7/076C21C7/00
CPCC21C5/35C21C7/0006C21C7/0025C21C7/0087C21C7/06C21C7/076C22C38/02C22C38/04C22C38/06C22C38/14Y02P10/20
Inventor 刘复兴汪晛余爱华方建红夏金魁黄道昌廖广府严敏
Owner WUHAN IRON & STEEL GRP ECHENG IRON & STEEL CO LTD