Rare earth treatment method of continuously cast 20 steel crack-free tube blank

A treatment method and crack-free technology, applied in the field of iron and steel metallurgy, can solve problems such as surface cracks, end cracks of 20 steel pipes, subcutaneous cracks of 20 steel pipe billets, etc., and achieve the effects of eliminating cracks, reducing columnar crystal regions, and expanding equiaxed crystal regions

Inactive Publication Date: 2011-04-20
BAOTOU SHENRUI SPECIAL ALLOY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] At present, rare earth treatment is not used in the production of continuous casting 20 steel pipe slabs, and the produced 20 steel pipe slabs often have subcutaneous cracks, resulting in end cracks and surface cracks often occurring in 20 steel pipes, and the performance of the steel pipes needs to be further improved

Method used

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  • Rare earth treatment method of continuously cast 20 steel crack-free tube blank
  • Rare earth treatment method of continuously cast 20 steel crack-free tube blank
  • Rare earth treatment method of continuously cast 20 steel crack-free tube blank

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] Continuous casting of 20 steel, 100×100mm billet, smelting in converter, chemical composition (%) C0.18 Si0.045 Mn0.015P0.002 S0.040, 150 tons converter, submerged nozzle, molten steel surface plus protective agent, drawing Billet speed, 2 meters per minute, molten steel enters the tundish, feeds rare earth wire cored wire (φ=2.5mm LaCe wire, coated with 0.1mm iron sheet) on the side of the nozzle with a wire feeder in the crystallizer, V 丝 = 4m / min. In the process of pouring 20 steel, rare earth was added to the first 75 tons with a wire feeder, and no rare earth was added to the last 75 tons. Samples were taken from the cast slab and rolled material for inspection and comparison.

[0042] Table 1 Results of RE analysis on the cross-section of the slab %

[0043]

[0044] Table 2 metallographic image analyzer measurement results

[0045]

[0046]

[0047] Table 3 Analysis results of slab electrolytic inclusions (%)

[0048]

[0049] Table 4 Effect of rar...

Embodiment 2

[0054] Continuous casting 20 steel, 140×140mm square billet, smelting in converter, chemical composition (%) C 0.17, SiO 2 0.044, Mn0.016, P 0.003, S 0.045, 150-ton converter, submerged nozzle, mold slag, casting speed, 2 meters per minute, molten steel enters the tundish, and the LZ-81-1 vertical wire feeder is used at the nozzle Between the crystallizer and the rare earth silk cored wire fed into the crystallizer, V 丝 = 5 m / min. In the process of pouring 20 steel, rare earth was added to the first 75 tons with a wire feeder, and no rare earth was added to the last 75 tons. Samples were taken from the cast and rolled materials for inspection and comparison.

[0055] Table 520 Steel Rare Earth Treated Slab Cross-Longitudinal Section [RE] and [S] Distribution (%)

[0056]

Location

1

2

3

4

5

6

7

8

[RE]

0.036

0.031

0.030

0.028

0.033

0.038

0.035

0.035

[S]...

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Abstract

The invention relates to a rare earth treatment method of a continuously cast 20 steel crack-free tube blank, belonging to the ferrous metallurgical field. The method is as follows: the cored wire feeding speed of the rare earth metal wire changes with the casting speed of a continuous casting machine, rare earth is distributed uniformly in the casting blank; the cored wire of a rare earth wire is inserted from one side of a submerged entry nozzle, the optimum insertion depth is 150mm; the optimum weight ratio of rare earth (RE/S) to sulfur in molten steel is 4.2; when the RE/S is 1.7, rare earth can be used to increase the equiaxed crystal rate of the 20 steel tube blank, reduce the columnar zone, disorder the first interference direction turbulence, decrease the secondary interference space, improve the central refraction and reduce the subsurface cracks; and when the RE/S is 4.2, rare earth can be used to completely change the morphologies of the inclusions in steel, convert manganese sulfide, silica, aluminium oxide and other inclusions to rare earth sulfide, rare earth oxysulfide, rare earth silicate, rare earth aluminate and the like, eliminate the inner cracks in the 20 steel tube blank and increase the transverse properties of the tube.

Description

technical field [0001] The invention relates to a rare earth treatment method for continuous casting 20-steel crack-free pipe billet, which belongs to the field of iron and steel metallurgy. Background technique [0002] At present, rare earth treatment is not used in the production of continuous casting 20 steel pipe slabs, and the produced 20 steel pipe slabs often have subcutaneous cracks, resulting in end cracks and surface cracks often occurring in 20 steel pipes, and the performance of the steel pipes needs to be further improved. Contents of the invention [0003] The object of the present invention is to provide a rare earth treatment method for continuous casting 20 steel tube billets without cracks, which can eliminate cracks and improve the performance of the pipe during the production process of continuous casting 20 steel tube billets. [0004] Technical solution: [0005] In the present invention, the rare earth metal wire cored wire is fed into the molten s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22D11/11C22C33/04
Inventor 渠天盛胡宗林李佩璋杨富强渠天霞
Owner BAOTOU SHENRUI SPECIAL ALLOY
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