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A smelting method to reduce the occurrence rate of edge cracking of 45 steel plate

A smelting method and technology of occurrence rate, which is applied in the smelting field to reduce the occurrence rate of 45 steel plate edge cracks, can solve problems such as increasing crack sensitivity, restricting output and quality, and affecting enterprise benefits, so as to reduce the occurrence rate of edge cracks and reduce production costs. Low, easy-to-operate effect

Active Publication Date: 2021-07-23
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 bl...

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 occurrence rate of edge cracking of 45 steel plates, which comprises the following steps: (1) increasing the ratio of molten iron, adding molten iron and scrap steel at a ratio of 4.5 to 5:1; (2) reblowing the top and bottom Bottom blowing argon throughout the converter blowing process; (3) Weak deoxidation process is implemented in the converter tapping process; (4) Low aluminum consumption control is implemented in the LF ladle furnace refining process; (5) The temperature for the precipitation of TiN by the reaction of titanium and nitrogen is higher than Adjust the temperature of the reaction between aluminum and nitrogen, adjust the steelmaking process, and add ferro-titanium for nitrogen fixation in the later stage of refining to reduce the combination of nitrogen and aluminum; (6) Control the N content and Al content in the steel; (7) Use a small taper crystallizer, Optimize the cooling effect of the crystallizer; (8) Properly increase the speed of continuous casting of different cross-sectional specifications, shorten the residence time of the slab in the secondary cooling section, appropriately reduce the amount of secondary cooling water, increase the temperature of the corner of the slab, and avoid the brittle zone of 700‑900 °C; The above process control has achieved the purpose of reducing the occurrence rate of edge cracks in 45 steel plates.

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 Patents(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