Production process of low-carbon low-silicon high-titanium steel

Abstract

The invention discloses a low-carbon low-silicon high-titanium steel production process, which comprises the following steps: converter tapping is carried out, lime and fluorite balls are used for slag washing, aluminum ingots are used for deoxidation, after tapping is finished, a slagging-off station is hoisted for slagging-off operation, and slagging-off is required to be carried out to a mirror surface; lime and synthetic slag are used in a refining furnace for slagging, high-purity alloy is required to be adopted for fine adjustment of components during refining, the alkalinity of refining final slag is required to be controlled between 5.0 and 7.0, a soft argon blowing hole and a wire feeding slag liquid level are covered with a magnesium covering agent after refining of high titanium steel is finished, and then carbonized rice husks are used for covering and heat preservation; the low-carbon low-silicon high-titanium steel is produced through an integral tank, a continuous casting impact area and a casting area are covered with a high-alkalinity covering agent for continuous casting after casting is started, the covering agent is covered with carbonized rice husks for heat preservation, and the black liquor surface is guaranteed. According to the technology, the requirement that the silicon content in the high-titanium steel is not larger than 0.030% can be met, and the continuous casting castability of the high-titanium molten steel can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of steel manufacturing, and in particular to a production process of low-carbon, low-silicon and high-titanium steel. Background Art

[0002] Titanium is an essential element in special welding steels. Titanium forms carbon and nitride precipitation during microalloying, and plays a role in fine grain and precipitation strengthening in steel. Therefore, it is widely used in the steelmaking production process of special steels. However, titanium is an element that is easily oxidized and has active metallic properties. Adding titanium to steel can easily produce a large amount of Ti inclusions in molten steel, which not only has a great impact on the fluidity of molten steel, but also the Ti in the steel can easily undergo a substitution reaction with SiO2 in the refining slag and covering agent, thereby causing the Si component in the steel to change, resulting in the finished product composition not meeting the steel grade requirements. For low-carbon, low-silicon, high-titanium steels, how to reduce titanium loss and increase silicon in the production process and ensure stability during continuous casting is a topic that steel companies are currently working on. Summary of the invention

[0003] In order to solve the problems raised in the above background technology, the present invention provides a production process of low-carbon, low-silicon and high-titanium steel.

[0004] To achieve the above object, the present invention provides the following technical solution: a production process of low-carbon, low-silicon and high-titanium steel, the process comprising the following steps in sequence:

[0005] S1. Converter process: lime and fluorite balls are used to wash the slag during the converter steelmaking process and aluminum ingots are used for deoxidation. After steelmaking is completed, the slag is removed to a mirror surface.

[0006] S2. Refining process: The refining furnace uses lime + synthetic slag for slag making, and the basicity of the final slag is required to be controlled between 5.0-7.0. After the refining of high titanium steel, the soft blowing argon eye and the wire feeding slag liquid surface are covered with a magnesium covering agent to ensure that the steel liquid surface is not exposed during soft blowing and the steel liquid can only contact the magnesium covering agent. Then, carbonized rice husks are used for covering and insulation to ensure the black liquid surface. Before feeding titanium wire, Si in the steel is required to be ≤0.015%, and the soft blowing argon gas flow rate during the wire feeding process is controlled at 30-40NL / min;

[0007] S3. Continuous casting process: Low-carbon, low-silicon, high-titanium steel is produced using integral tanks. After pouring, the continuous casting impact zone and casting zone are covered with high-alkalinity covering agents for continuous pouring. Carbonized rice husks are used to cover and keep the high-alkalinity covering agents warm, and the black liquid level must be guaranteed.

[0008] Preferably, the low-carbon, low-silicon, high-titanium steel requires that the percentages of titanium and silicon in the steel satisfy: Ti≧0.16%, Si≤0.030%.

[0009] Preferably, the refining process requires the use of high-purity alloys for fine-tuning the composition, and the Si content of the alloy is required to be less than 0.5%.

[0010] Preferably, the chemical composition of the fluorite ball by weight percentage is: CaF2≥85%, SiO2≤3.0%, Fe2O3≦1.0%, and moisture≤1.0%.

[0011] Preferably, the chemical composition of the magnesium covering agent by weight percentage is: MgO≧80%, Al2O3≦5.0%, SiO2≤1.0%, Fe2O3≦1.0%, moisture≤1.0%, free C≦2.0%, and the proportion of magnesium covering agent with a particle size of ≧2 mm is ≦5%.

[0012] Preferably, the chemical composition of the refined synthetic slag agent by weight percentage is: CaO 50-55%, Al2O3 30%-35%, MgO≤6.0%, Fe2O3≦1.0%, moisture ≤1.0%, free C≦2.0%, particle size ≧2mm, and the proportion of synthetic slag agent ≦5%.

[0013] Preferably, the low-carbon, low-silicon, high-titanium steel continuous casting is produced using an integral tank, and the high-basicity covering agent requires a basicity greater than 2.0 and SiO2≤2.0%.

[0014] Preferably, the continuous casting impact zone and casting zone are covered with a high basicity covering agent for continuous casting, wherein 80-100 kg of high basicity covering agent is added to the impact zone, and 200-220 kg of high basicity covering agent is added to the casting zone.

[0015] Preferably, in the converter steelmaking process, aluminum ingots are first used for deoxidation and then other alloys are used for alloying. Samples are required to be taken after the furnace, and the AL content in the steel is 0.015-0.035%.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention discloses a new method for reducing silicon increase in high titanium steel by slagging after the converter, controlling the basicity of the final refined slag with synthetic slag and using a magnesium covering agent instead of a traditional covering agent. According to measurements, by adopting this process in the production process, the Si content in the low-carbon, low-silicon high titanium steel can be stably controlled within 0.030% and the continuous casting of this type of steel can be stable. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] Example

[0020] This embodiment takes the production process of smelting HQ23-1 low-carbon, low-silicon, high-titanium steel as an example. The chemical composition of this steel is as follows:

[0021]

[0022] The process steps are as follows:

[0023] 1. Converter smelting: The converter bottom blowing requires argon blowing throughout the process, the sulfur content of the hot metal entering the furnace is less than 0.001%, and the self-produced first-class scrap steel is used. The carbon requirement of the converter steel is less than 0.04%, the target is 0.030%-0.040%, the steel tapping temperature is 1605℃, the steel tapping phosphorus is 0.009%, and the steel tapping sulfur is 0.005%. Low-carbon manganese and aluminum ingots are added during the steel tapping process for deoxidation and alloying. In addition, 500Kg of lime + 50Kg of fluorite balls are used for slag washing, and then the slag is removed at the slag removal station. The components of the samples taken after the furnace are as follows:

[0024]

[0025]

[0026] 2. Refining: Slag making process: 300Kg lime + 600 synthetic slag; temperature raising, slag melting, deoxidation (using calcium carbide for full deoxidation) until sampling (steel sample and slag sample) oxygen determination (20 minutes, expected 1560℃, 15ppm), continue deoxidation, adjust composition (use metal manganese and nickel plates to fine-tune composition), after Mn, Ni composition and temperature meet the requirements of steel grade, feed titanium wire and ferroboron into steel, finally feed appropriate amount of calcium wire (20-40m) according to AL content in steel and soft blow, detect the basicity of refined final slag 5.2, then cover the soft blow argon eye and wire feeding slag liquid surface with magnesium covering agent, ensure that the steel liquid surface cannot be exposed during soft blowing and the steel liquid can only contact with magnesium covering agent, use carbonized rice husk to cover and keep warm above the covering agent, must ensure black liquid surface, soft blow for 10-15min, take steel sample, the composition is as follows:

[0027]

[0028] 3. Continuous casting: The impact zone and casting zone of continuous casting are covered with high alkalinity covering agent for continuous casting, of which 80-100kg is added to the impact zone and 200-220kg is added to the casting zone. Carbonized rice husk is used to cover and keep warm on the covering agent. The black liquid level must be guaranteed. Samples of smelted products are taken from the casting zone. The composition is as follows:

[0029]

[0030] By adopting this process, the composition of HQ23-1 steel not only meets customer requirements, but also ensures a smooth continuous casting process, with a billet forming rate of 93%.

[0031] In this embodiment, the chemical composition of the fluorite ball by weight is: CaF2 ≥ 85%, SiO2 ≤ 3.0%, Fe2O3 ≤ 1.0%, and moisture ≤ 1.0%. The chemical composition of the magnesium covering agent by weight is: MgO ≧ 80%, Al2O3 ≤ 5.0%, SiO2 ≤ 1.0%, Fe2O3 ≤ 1.0%, moisture ≤ 1.0%, free C ≤ 2.0%, and the proportion of magnesium covering agent with a particle size of ≧ 2 mm is ≤ 5%. The chemical composition of the refining synthetic slag agent by weight is: CaO 50-55%, Al2O3 30%-35%, MgO ≤ 6.0%, Fe2O3 ≤ 1.0%, moisture ≤ 1.0%, free C ≤ 2.0%, and the proportion of synthetic slag agent with a particle size of ≧ 2 mm is ≤ 5%.

[0032] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A production process for low-carbon, low-silicon and high-titanium steel, characterized in that: The process comprises the following steps in sequence: S1. Converter process: lime and fluorite balls are used to wash the slag during the converter steelmaking process and aluminum ingots are used for deoxidation. After steelmaking is completed, the slag is removed to a mirror surface. S2. Refining process: The refining furnace uses lime + synthetic slag for slag making, and the basicity of the final slag is required to be controlled between 5.0-7.

0. After the refining of high titanium steel, the soft blowing argon eye and the wire feeding slag liquid surface are covered with a magnesium covering agent to ensure that the steel liquid surface is not exposed during soft blowing and the steel liquid can only contact the magnesium covering agent. Then, carbonized rice husks are used for covering and insulation to ensure the black liquid surface. Before feeding titanium wire, Si in the steel is required to be ≤0.015%, and the soft blowing argon gas flow rate during the wire feeding process is controlled at 30-40NL / min; S3. Continuous casting process: Low-carbon, low-silicon, high-titanium steel is produced using integral tanks. After pouring, the continuous casting impact zone and casting zone are covered with high-alkalinity covering agents for continuous pouring. Carbonized rice husks are used to cover and keep the high-alkalinity covering agents warm, and the black liquid level must be guaranteed.

2. The low-carbon, low-silicon, high-titanium steel production process according to claim 1 is characterized in that: The low-carbon, low-silicon, high-titanium steel is required to have titanium and silicon content percentages that meet the following requirements: Ti≧0.16%, Si≤0.030%.

3. The low-carbon, low-silicon, high-titanium steel production process according to claim 1 is characterized in that: The refining process requires the use of high-purity alloys for fine-tuning the composition, and the Si content of the alloy is required to be less than 0.5%.

4. The low-carbon, low-silicon, high-titanium steel production process according to claim 1 is characterized in that: The chemical composition of the fluorite ball is as follows by weight percentage: CaF2≥85%, SiO2≤3.0%, Fe2O3≤1.0%, and moisture≤1.0%.

5. The low-carbon, low-silicon, high-titanium steel production process according to claim 1, characterized in that: The chemical composition of the magnesium covering agent by weight percentage is: MgO≧80%, Al2O3≦5.0%, SiO2≤1.0%, Fe2O3≦1.0%, moisture≤1.0%, free C≦2.0%, and the proportion of magnesium covering agent with a particle size of ≧2mm is ≦5%.

6. The low-carbon, low-silicon, high-titanium steel production process according to claim 1 is characterized by: The chemical composition of the refining synthetic slag agent by weight percentage is: CaO 50-55%, Al2O3 30%-35%, MgO≤6.0%, Fe2O3≦1.0%, moisture ≤1.0%, free C≦2.0%, and the proportion of synthetic slag agent with particle size ≧2mm is ≦5%.

7. The low-carbon, low-silicon, high-titanium steel production process according to claim 1 is characterized by: The low-carbon, low-silicon, high-titanium steel continuous casting is produced using an integral tank, and the high-basicity covering agent requires a basicity greater than 2.0 and SiO2≤2.0%.

8. The low-carbon, low-silicon, high-titanium steel production process according to claim 1 is characterized by: The continuous casting impact zone and casting zone are covered with a high basicity covering agent for continuous casting, wherein 80-100 kg of high basicity covering agent is added to the impact zone, and 200-220 kg of high basicity covering agent is added to the casting zone.

9. The low-carbon, low-silicon, high-titanium steel production process according to claim 1 is characterized by: The converter steelmaking process first uses aluminum ingots for deoxidation and then uses other alloys for alloying. Sampling after the furnace is required, and the AL content in the steel is 0.015-0.035%.

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