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Method for reducing surface cracks of boron containing steel continuous casting sheet billet

A technology of surface cracking and continuous casting, applied in the field of iron and steel metallurgy, can solve the problems of irreparable, scrapped cast slabs, serrated cracks in steel plates, etc.

Inactive Publication Date: 2016-04-06
SHANDONG IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Continuous casting of boron-containing steel is prone to transverse crack defects, which can appear on the edge of the slab and the inner arc surface of the slab, and can only be rescued by flame cleaning. However, when the crack is deep, flame cleaning cannot repair it, resulting in casting Blank scrap
Incomplete cleaning of crack defects will lead to the formation of jagged crack defects in the steel plate

Method used

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  • Method for reducing surface cracks of boron containing steel continuous casting sheet billet

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034]The continuous casting machine used is an ultra-low-head slab continuous casting machine. The metallurgical length of the casting machine is 17m, and the arc radius is R5.7 / 6.8 / 8.5 / 12 / 17 / 33—1500. It is composed of 7 segments, of which 3, The fourth section is the straightening section, and the annual production capacity of the casting machine is 900,000 tons / year. Prepare American Standard S355JR-B series boron-containing steel, its standard composition control (mass percentage) is: including 0.14%~0.18% C, 0.10%~0.30% Si, 1.32%~1.52% Mn, 0.025% or less P, 0.010% of S, 0.020% to 0.035% of Nb, 0.0008% to 0.0020% of B, 0.015% or more of Als, 0.008% to 0.022% of Ti, and the balance is Fe and unavoidable impurity elements.

[0035] 1) Molten steel smelting: After converter smelting, carry out LF refining, deoxidize until the oxygen content of molten steel is below 0.0050%, then add ferro-titanium and then ferroboron at the later stage of LF refining to control the compositio...

Embodiment 2

[0042] The continuous casting machine used is an ultra-low-head slab continuous casting machine. The metallurgical length of the casting machine is 17m, and the arc radius is R5.7 / 6.8 / 8.5 / 12 / 17 / 33—1500. It is composed of 7 segments, of which 3, The fourth section is the straightening section, and the annual production capacity of the casting machine is 900,000 tons / year. Prepare American Standard S355JR-B series boron-containing steel, its standard composition control (mass percentage) is: including 0.14%~0.18% C, 0.10%~0.30% Si, 1.32%~1.52% Mn, 0.025% or less P, 0.010% of S, 0.020% to 0.035% of Nb, 0.0008% to 0.0020% of B, 0.015% or more of Als, 0.008% to 0.022% of Ti, and the balance is Fe and unavoidable impurity elements.

[0043] 1) Molten steel smelting: After converter smelting, carry out LF refining, deoxidize until the oxygen content of molten steel is below 0.0050%, then add ferro-titanium and then ferroboron at the later stage of LF refining to control the compositi...

Embodiment 3

[0050] The continuous casting machine used is an ultra-low-head slab continuous casting machine. The metallurgical length of the casting machine is 17m, and the arc radius is R5.7 / 6.8 / 8.5 / 12 / 17 / 33—1500. It is composed of 7 segments, of which 3, The fourth section is the straightening section, and the annual production capacity of the casting machine is 900,000 tons / year. Prepare American Standard S355JR-B series boron-containing steel, its standard composition control (mass percentage) is: including 0.14%~0.18% C, 0.10%~0.30% Si, 1.32%~1.52% Mn, 0.025% or less P, 0.010% of S, 0.020% to 0.035% of Nb, 0.0008% to 0.0020% of B, 0.015% or more of Als, 0.008% to 0.022% of Ti, and the balance is Fe and unavoidable impurity elements.

[0051] 1) Molten steel smelting: After converter smelting, carry out LF refining, deoxidize until the oxygen content of molten steel is below 0.0050%, then add ferro-titanium and then ferroboron at the later stage of LF refining to control the compositi...

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Abstract

The invention discloses a method for reducing surface cracks of a boron containing steel continuous casting sheet billet. Firstly, a boron containing steel component is controlled in an optimized manner, ferroboron is added under the situation that molten steel oxygen removing is good, the boron recycling rate is increased, and the control stability of the boron component is guaranteed; and titanium is utilized for capturing nitrogen needed for forming boron nitride, precipitation of boron nitride particles is restrained, thermoplasticity of boron containing steel is improved, and titanium nitride is high in stability, low in high-temperature solubility, not prone to roughing and capable of refining grains. Furthermore, optimal control is carried out on the continuous casting technology, the secondary cooling area specific water flow, the sheet billet outlet straightening area temperature, the throwing pressure and the front and rear roller smooth arc deviation are controlled, the crack defect ratio of the boron containing steel sheet billet is greatly reduced to be below 1.5% from the original 9.3%, the surface quality of the continuous casting sheet billet is improved, and accordingly the quality of final products is improved.

Description

technical field [0001] The invention relates to the technical field of iron and steel metallurgy, in particular to a method for reducing cracks on the surface of boron-containing steel continuous casting slabs. Background technique [0002] Boron steel is a low-alloy structural steel based on Mn and B instead of Cr and Ni. Adding trace amounts of boron to steel can significantly improve hardenability. Its effect is equivalent to hundreds of times that of general alloying elements such as manganese, chromium, and nickel, so trace amounts of boron can be used instead of large amounts of alloying elements. At the same time, boron can also improve the high temperature strength and creep strength of heat-resistant steel, improve the red hardness of high-speed steel and the cutting ability of cutting tools. From this point of view, boron steel not only enhances the comprehensive performance of steel, but also reduces production costs. In recent years, domestic and foreign steel...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22D11/117C21C7/06
CPCB22D11/117C21C7/06
Inventor 楚志宝江永波董慧苏建军陈常义庞志忠李长新刘存芳付廷强付庆林
Owner SHANDONG IRON & STEEL CO LTD
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