Smelting process capable of lowering TiN inclusion content in high-titanium microalloyed high-strength steel

A technology of micro-alloying and high-strength steel, which is applied in the manufacture of converters, etc., can solve the problems of high stirring temperature drop, inability to guarantee, and high nitrogen content in molten steel, so as to reduce the quantity and size, improve the purity of molten steel, and have good low-temperature toughness Effect

Pending Publication Date: 2018-12-25
HANDAN IRON & STEEL GROUP +1
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Problems solved by technology

[0004] The conventional Nb-Ti microalloyed high-strength steel smelting process adopts "converter-LF refining-RH refining-continuous casting". Due to the relatively low Ti content, the control of TiN inclusion content is not specially considered in the steelmaking process, resulting in the N content of molten steel. It is stable at a relatively low level, mainly manifested in the following aspects: First, complete deoxidation is carried out during the tapping process of the converter, and there is no requirement for the degree of deoxidation. Slag desulfurization takes a long time, and the temperature of molten steel is much lowered by stirring. It takes a long time to power on and heat up, and the nitrogen increase is serious in the process. It can be seen that the existing Nb-Ti microalloyed high-strength steel smelting process is not conducive to the reduction of N content, so it is not applicable It is suitable for the production of high-Ti micro-alloyed high-strength steel; at the same time, the RH refining pure degassing time of the existing Nb-Ti micro-alloyed high-strength steel smelting process is 6-8 minutes, and the temperature superheat of the continuous casting tundish is 20±10°C. ; This pure degassing time cannot guarantee that when producing high-Ti steel, a large amount of titanium alloy is added to molten steel to produce inclusions that fully float up, and casting at a superheat of 20±10°C is likely to cause liquidation growth of TiN inclusions

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  • Smelting process capable of lowering TiN inclusion content in high-titanium microalloyed high-strength steel
  • Smelting process capable of lowering TiN inclusion content in high-titanium microalloyed high-strength steel
  • Smelting process capable of lowering TiN inclusion content in high-titanium microalloyed high-strength steel

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Experimental program
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Effect test

Embodiment 1

[0035] A 250-ton top-bottom double-blown converter is used for smelting. The continuous casting machine adopts an arc-shaped double-strand continuous casting machine. There are 17 segments in the continuous casting machine. The steel type is 700L high-strength automobile beam steel, and the components (wt%) of each element are as follows: C:0.065-0.085, Si:≤0.1, Mn:1.40-1.50, P:≤0.014, S:≤0.003, Ti:0.090-0.115, gas N:≤0.0055; the specific smelting steps are as follows:

[0036] Hot metal pre-desulfurization process: The initial sulfur content in the hot metal is 0.036wt%, and through the pre-desulfurization process, 344kg of magnesium powder and 950kg of lime powder are sprayed, and the sulfur content is reduced to 0.008wt% after the slag removal operation;

[0037] Converter process: molten iron enters the converter for blowing for 15 minutes, blowing end point temperature is 1645°C, blowing off C is 0.031wt%, P is 0.0087wt%; tapped for deoxidation alloying, adding aluminum co...

Embodiment 2

[0046] A 250-ton top-bottom double-blown converter is used for smelting. The continuous casting machine adopts an arc-shaped double-strand continuous casting machine. There are 17 segments in the continuous casting machine. : C: 0.055-0.075%, Si: ≤0.1%, Mn: 1.50-1.60%, P: ≤0.014%, S: ≤0.003%, Ti: 0.110-0.125%, Gas N: ≤0.0055%. Specific steps are as follows:

[0047] Pre-desulfurization process of molten iron: The initial sulfur content of molten iron is 0.041wt%. Through the pre-desulfurization process, 381kg of magnesium powder and 1080kg of lime powder are sprayed, and the sulfur content is reduced to 0.007wt% after the slag removal operation;

[0048] Converter process: The molten iron enters the converter for blowing for 15 minutes, the end point temperature is 1621°C, the blow-off C is 0.037wt%, and the P is 0.0065wt%. The steel is tapped for deoxidation and alloying, and 398kg of aluminum composite deoxidizer and 445kg of aluminum block are added. Steel end molten steel...

Embodiment 3

[0057] A 250-ton top-bottom double-blown converter is used for smelting. The continuous casting machine adopts an arc-shaped double-strand continuous casting machine. There are 17 segments in the continuous casting machine. , C: 0.055-0.075, Si: ≤0.1, Mn: 1.50-1.60, P: ≤0.014, S: ≤0.003, Ti: 0.110-0.125, gas N: ≤0.0055%; the specific steps are as follows:

[0058] Pre-desulfurization process of molten iron: The initial sulfur content of molten iron is 0.042wt%. Through the pre-desulfurization process, 415kg of magnesium powder and 870kg of lime powder are sprayed, and the sulfur content is reduced to 0.007wt% after the slag removal operation;

[0059] Converter process: The molten iron enters the converter for blowing for 14 minutes, the end temperature is 1619°C, the blow-off C is 0.039wt%, and the P is 0.0093wt%. The steel is tapped for deoxidation and alloying, and 421kg of aluminum composite deoxidizer and 400kg of aluminum block are added. Acid-soluble aluminum in molten ...

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Abstract

The invention relates to a smelting process capable of lowering TiN inclusion content in high-titanium microalloyed high-strength steel. According to a molten iron pre-desulfuration process, it is required that the S content of molten iron is controlled below 0.010 wt% after the process is finished; according to a converter process, it is required that molten steel is deoxidized in tapping, and Als of the molten steel is controlled to be 0.0050-0.0150 wt%; according to an LF refining process, firstly, slagging desulfuration is carried out, the S content is lowered to below the required S content of the steel grade within 10 minutes, and the treatment period is controlled to be 25-30 minutes; according to an RH refining process, the vacuum degree reaches 1 mbar or below within 1.5 minutes of molten steel circulation, and composition regulation is completed within in 3 minutes; according to a continuous casting process, the superheat degree of tundish molten steel is controlled to be 13-23 DEG C, and the billet pulling rate is 1.10-1.20 m / min; and dynamic soft reduction is adopted in the course. The smelting process can effectively lower the quantity and dimension of TiN inclusions in molten steel of the high-titanium microalloyed high-strength steel, so that the purity of molten steel and the casting blank quality are improved.

Description

technical field [0001] The invention relates to a smelting process for reducing the content of TiN inclusions in high-titanium microalloyed high-strength steel, and belongs to the technical field of steelmaking processes. Background technique [0002] Nb-Ti micro-alloyed high-strength steel with high strength, high toughness and good weldability has been widely used in engineering, machinery, automobiles and other fields, realizing the environmental protection benefits of lightweight engineering structures and energy saving and emission reduction. However, the price of niobium alloy is more expensive, which increases the production cost of steel, while the price of titanium alloy is relatively low, and Ti also has a strong effect of fine grain strengthening and precipitation strengthening; therefore, in order to reduce the cost of high-strength structural steel, Ti replaces Nb. The development and production of high-strength engineering structural steel has become a research...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C1/02C21C5/28C21C7/10C21C7/064B22D11/16
CPCB22D11/16C21C1/02C21C5/28C21C7/064C21C7/10
Inventor 朱坦华李斌路殿华贾改风王文录李红俊柳风林吴明英
Owner HANDAN IRON & STEEL GROUP
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