阅读说明：本技术 一种电炉生产弹簧钢的精炼工艺 (Refining process for producing spring steel by electric furnace ) 是由 李小虎 高振波 龚志翔 王尚 何云龙 于 2019-10-09 设计创作，主要内容包括：本发明公开了一种电炉生产弹簧钢的精炼工艺,属于钢铁冶炼技术领域。本发明步骤为：步骤一：电炉冶炼；a)以废钢和铁水为原料；b)采用偏心炉底出钢防止下渣,精炼回磷量≤0.005％；出钢温度1620℃以上；c)电炉出钢过程中全程底吹氩气搅拌；步骤二：LF炉冶炼；a)前期使用石灰、电石和硅钙钡脱氧造渣,后期使用碳化硅和电石保渣；b)精炼渣成分要求：CaO％48-55％、SiO2％23-28％、Al2O3％＜15％、MgO％5-8％、TFe+MnO％≤0.8％；步骤三：RH冶炼。本发明能够实现对精炼渣成分的精确控制,无需加入石英砂进行调渣,同时通过渣量控制、搅拌控制、过程保渣等方式能够保证钢水温度、精炼渣成分的稳定控制,减少钢水二次氧化,精炼渣脱氧能力较强,有效达到了深脱氧和深脱硫的目的。(The invention discloses a refining process for producing spring steel by an electric furnace, belonging to the technical field of steel smelting. The method comprises the following steps: the method comprises the following steps: smelting in an electric furnace; a) taking scrap steel and molten iron as raw materials; b) the eccentric furnace bottom tapping is adopted to prevent slag from falling, and the refining phosphorus return amount is less than or equal to 0.005 percent; the tapping temperature is above 1620 ℃; c) bottom blowing argon gas and stirring in the whole process of electric furnace tapping; step two: smelting in an LF furnace; a) lime, calcium carbide and silicon-calcium-barium are used for deoxidation and slagging in the early stage, and silicon carbide and calcium carbide are used for slag protection in the later stage; b) the refining slag comprises the following components: 48-55 percent of CaO, 23-28 percent of SiO2, less than 15 percent of Al2O3, 5-8 percent of MgO, and less than or equal to 0.8 percent of TFe and MnO; step three: and (4) RH smelting. The method can realize the accurate control of the components of the refining slag, does not need to add quartz sand for slag adjustment, can ensure the stable control of the temperature of the molten steel and the components of the refining slag by the modes of slag amount control, stirring control, process slag retention and the like, reduces the secondary oxidation of the molten steel, has stronger deoxidizing capacity of the refining slag, and effectively achieves the aims of deep deoxidation and deep desulfurization.)

1. A refining process for producing spring steel by an electric furnace is characterized by comprising the following steps: the method comprises the following steps:

the method comprises the following steps: smelting in an electric furnace;

a) the method is characterized in that scrap steel and molten iron are used as raw materials, the molten iron S is less than or equal to 0.060 percent, the molten iron is not required to be pretreated, and the molten slag is dephosphorized under the low-temperature condition in the early stage of the electric furnace, so that the finished product phosphorus can meet the product requirement;

b) the eccentric furnace bottom tapping is adopted to prevent slag from falling, and the refining phosphorus return amount is less than or equal to 0.005 percent; the tapping temperature is above 1620 ℃;

c) argon is blown from the bottom in the whole process of the electric furnace steel tapping process for stirring, feeding is started when the steel tapping amount reaches more than 20 tons, a deoxidizing agent is added firstly, the deoxidizing agent adopts low-carbon low-titanium ferrosilicon or ferrosilicon, then alloy and slag charge are added, and the adding is completed before the steel tapping is finished;

step two: smelting in an LF furnace;

a) strictly controlling the bottom blowing stirring strength in the refining process, using large argon for strong stirring in early-stage desulfurization, using stirring in middle and later-stage slag retention, controlling the diameter of the bright surface of the molten steel to be 300-600mm, and reducing secondary oxygen absorption caused by over-exposure of the molten steel and secondary entering of impurities in slag into the molten steel while ensuring the dynamic condition of steel slag interface reaction;

b) the temperature is raised to the target temperature in the early period, and the oxygen absorption of molten steel and top slag caused by the large fluctuation of the temperature of the molten steel is avoided in the slag retention process in the middle and later periods;

c) lime, calcium carbide and silicon-calcium-barium are used for deoxidation and slag making in the early stage, the dosage of the lime is 7.0-8.5 kg per ton of steel, the dosage of the calcium carbide is 0.5-1.0 kg per ton of steel, and the dosage of the silicon-calcium-barium is 1.0-1.5 kg per ton of steel;

d) silicon carbide and calcium carbide slag are used in the processes of heating and slag retention, a small amount of silicon carbide and calcium carbide slag are added in batches, 10-20 kg of silicon carbide and calcium carbide are added every 5-10 minutes, the proportion of the silicon carbide and the calcium carbide is controlled according to the alkalinity of the refining slag to finely adjust the alkalinity of the refining slag, and the target alkalinity is 1.8-2.2;

step three: and (4) RH smelting.

2. The refining process for producing spring steel by an electric furnace according to claim 1, wherein: the third step is that: deep vacuum treatment is adopted, the vacuum degree is kept below 100Pa for more than 10 minutes, and the [ H ] is less than or equal to 1.5ppm, simultaneously, the further removal of impurities is promoted, and soft blowing is carried out after vacuum.

3. The refining process for producing spring steel by an electric furnace according to claim 1, wherein: the first step is as follows: the slag material is lime, the adding amount of the lime is 3.0-4.0 kg per ton of steel, and the lime is increased by 0.4 kg per ton of steel when the oxygen value exceeds 100ppm by taking the fixed oxygen value as the reference.

4. The refining process for producing spring steel by an electric furnace according to claim 1, wherein: the first step is as follows: the adding amount of the low-carbon low-titanium ferrosilicon or ferrosilicon is as follows: and calculating the target value of the low-carbon low-titanium ferrosilicon or the consumption of the ferrosilicon by adopting a formula according to the LF arrival Si content requirement.

5. The refining process for producing spring steel by an electric furnace according to claim 1, wherein: the second step is that: the refining slag comprises the following components: 48-55 percent of CaO, 23-28 percent of SiO2, less than 15 percent of Al2O3, 5-8 percent of MgO, and less than or equal to 0.8 percent of TFe and MnO.

Technical Field

The invention relates to the technical field of steel smelting, in particular to a refining process for producing spring steel by an electric furnace.

Background

Spring steel is widely used in various equipments such as transportation means such as airplanes, automobiles, railway vehicles, and the like, and construction machines, and is a material for manufacturing various coil springs, torsion springs, plate springs, and springs of other shapes acting similarly. Compared with the prior art that the main spring steel refining slag technology is low-alkalinity slag, such as the spring steel refining method disclosed by the invention patent of China, the invention does not use quartz sand, magnesia and other materials, but directly adjusts the slag through a deoxidizer, thereby reducing the risk caused by secondary oxidation and further improving the stability of inclusion control. The Chinese invention patent discloses a smelting process for controlling inclusion of spring steel, which controls inclusion by controlling the alkalinity of refining slag to be 0.7-1.4, but the desulphurization is difficult under the alkalinity, particularly for molten steel with higher initial sulfur content, the refining slag is thinner under the alkalinity in the actual production, the temperature fluctuation of the molten steel is not easy to control, the requirements on molten iron and operation are higher, and quartz sand is also required to be added for slagging. Compared with the prior art, the process for smelting the Cr-Mn series spring steel has the advantages that the process does not need to change slag, the cost is greatly reduced, the risk of brittle alumina inclusions caused by incomplete removal of deoxidation products of early-stage aluminum deoxidation is avoided, the risk of secondary oxidation caused by slagging by using quartz sand is avoided, and the stability of inclusion control is further improved. In conclusion, the alkalinity control of the spring steel refining slag needs to realize the following aims: deep deoxidation and desulfurization to reduce the number of non-metallic inclusions; the precise control of the low-alkalinity slag is used for stably controlling the type of the nonmetallic inclusion; better operability to adapt to the field mass production. Therefore, the method is a great problem in the spring steel refining slag process.

Disclosure of Invention

1. Technical problem to be solved by the invention

Aiming at the defects and shortcomings in the prior art, the invention provides a refining process for producing spring steel by an electric furnace, which can realize accurate control of the components of refining slag through model calculation without adding quartz sand for slag adjustment, and can ensure stable change of molten steel temperature and the components of the refining slag through modes of slag quantity control, stirring control, process slag retention and the like, thereby reducing secondary oxidation of the molten steel.

2. Technical scheme

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the invention relates to a refining process for producing spring steel by an electric furnace, which comprises the following steps:

the method comprises the following steps: smelting in an electric furnace;

a) the method is characterized in that scrap steel and molten iron are used as raw materials, the molten iron S is less than or equal to 0.060 percent, the molten iron is not required to be pretreated, and the electric furnace is dephosphorized by utilizing low-temperature condition slag in the early stage, so that finished phosphorus can meet the product requirement;

b) the eccentric furnace bottom tapping is adopted to prevent slag from falling, and the refining phosphorus return amount is less than or equal to 0.005 percent; the tapping temperature is above 1620 ℃;

c) argon is blown from the bottom in the whole process of the electric furnace steel tapping process for stirring, feeding is started when the steel tapping amount reaches more than 20 tons, a deoxidizing agent is added firstly, the deoxidizing agent adopts low-carbon low-titanium ferrosilicon or ferrosilicon, then alloy and slag charge are added, and the adding is completed before the steel tapping is finished;

step two: smelting in an LF furnace;

a) strictly controlling the bottom blowing stirring strength in the refining process, using large argon for strong stirring in early-stage desulfurization, using stirring in middle and later-stage slag retention, controlling the diameter of the bright surface of the molten steel to be 300-600mm, and reducing secondary oxygen absorption caused by over-exposure of the molten steel and secondary entering of impurities in slag into the molten steel while ensuring the dynamic condition of steel slag interface reaction;

b) the temperature is raised to the target temperature in the early period, and the oxygen absorption of molten steel and top slag caused by the large fluctuation of the temperature of the molten steel is avoided in the slag retention process in the middle and later periods;

c) in the early stage, lime, calcium carbide and silicon-calcium-barium are used for deoxidation and slag making, the dosage of the lime is 7.0-8.5 kg per ton of steel, the dosage of the calcium carbide is 0.5-1.0 kg per ton of steel, and the dosage of the silicon-calcium-barium is 1.0-1.5 kg per ton of steel;

d) silicon carbide and calcium carbide slag are used in the processes of heating and slag retention, a small amount of silicon carbide and calcium carbide slag are added in batches, 10-20 kg of silicon carbide and calcium carbide are added every 5-10 minutes, the proportion of the silicon carbide and the calcium carbide is controlled according to the alkalinity of the refining slag to finely adjust the alkalinity of the refining slag, and the target alkalinity is 1.8-2.2;

step three: and (4) RH smelting.

Further, the third step: deep vacuum treatment is adopted, the vacuum degree is kept below 100Pa for more than 10 minutes, and the [ H ] is less than or equal to 1.5ppm, simultaneously, the further removal of impurities is promoted, and soft blowing is carried out after vacuum.

Further, the first step: the slag material is lime, the adding amount of the lime is 3.0-4.0 kg per ton of steel, and the lime is increased by 0.4 kg per ton of steel when the oxygen value exceeds 100ppm by taking the fixed oxygen value as the reference.

Further, the first step: the adding amount of the low-carbon low-titanium ferrosilicon or ferrosilicon is as follows: and calculating the target value of the low-carbon low-titanium ferrosilicon or the consumption of the ferrosilicon by adopting a formula according to the LF arrival Si content requirement.

Further, the second step: the refining slag comprises the following components: 48-55 percent of CaO, 23-28 percent of SiO2, less than 15 percent of Al2O3, 5-8 percent of MgO, and less than or equal to 0.8 percent of TFe and MnO.

3. Advantageous effects

Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:

the production process is controlled more stably, and the deoxidation alloying components of the electric furnace tapping are stable, so that the content of SiO2 in the slag is stable; the amount of rephosphorization of the electric furnace is controlled to avoid oxidizing slag of the electric furnace from entering the smelting process of the LF furnace; the alkalinity of the refining slag is stably controlled to be 1.8-2.2, meanwhile, the TFe and MnO percent do not exceed 1.0 percent, and the reducibility of the refining slag is kept good; from the perspective of S and total oxygen of finished products, the refining slag has strong deoxidizing capacity, the purposes of deep deoxidation and deep desulfurization are achieved, RH inclusion floating and continuous casting protective casting are very effective, the method can realize accurate control of refining slag components through model calculation, quartz sand is not required to be added for slag adjustment, and meanwhile, stable changes of molten steel temperature and refining slag components can be guaranteed through modes of slag amount control, stirring control, process slag retention and the like, and secondary oxidation of the molten steel is reduced.

Detailed Description

The invention is further described with reference to the following examples: