CN-121992169-A - IF steel clean smelting continuous casting method for automobile based on rare earth microalloying

Abstract

The invention relates to an IF steel clean smelting continuous casting method for an automobile based on rare earth microalloying, which comprises the steps of 1) preparing high-purity rare earth metal, 2) double-low-oxygen refining, 3) alloying in stages according to the sequence of aluminum deoxidation, mn/Ti microalloying and rare earth addition, and 4) anti-oxidation casting. By optimizing the rare earth adding process and controlling the oxygen content, refining and dispersing of inclusions are realized, the deep drawing performance is improved, and the stability of industrial production is improved.

Inventors

• HUANG JIAN
• LIU ZHANGMAN
• Tian Weiyang
• LIU JUN
• XING WEIYI
• LI GUANGMING
• ZHANG XIUXIANG

Assignees

• 本溪北营钢铁（集团）股份有限公司

Dates

Publication Date

20260508

Application Date

20260119

Claims (6)

1. 1. The clean smelting continuous casting method of the IF steel for the automobile based on rare earth microalloying is characterized by comprising the following steps of: 1) Preparing high-purity rare earth metal: the mass ratio of the high-purity rare earth metal is less than 60ppm, the total impurity amount is less than 500ppm, and the blocking degree is less than or equal to 50mm; 2) Double hypoxia refining: controlling LF refining end point according to mass ratio, where T O is less than or equal to 20ppm, T S is less than or equal to 60ppm, white slag time is more than or equal to 20min; The RH refining deep vacuum degree is less than or equal to 100Pa, the deep vacuum holding time is more than or equal to 3min, and the deep vacuum circulation time after adding high-purity rare earth metal is more than or equal to 10min; Alloying in stages: The method is carried out according to the sequence of aluminum deoxidation, mn/Ti microalloying and rare earth addition, specifically comprises the steps of aluminum deoxidation for more than 3min, controlling Tal to be 0.03% -0.05% according to the mass ratio, adding Mn and sponge Ti for microalloying for more than 3min, and then adding high-purity rare earth metal through an RH high-level bin; 4) And (3) anti-oxidation pouring: The continuous casting adopts argon seal protection, the argon flow between the tundish and the crystallizer is 10-150L/min, and the nitrogen absorption amount in the whole process is less than 5ppm.
2. 2. The method for cleaning, smelting and continuously casting the IF steel for the automobile based on rare earth microalloying according to claim 1, wherein the high-purity rare earth metal is high-purity lanthanum cerium rare earth metal.
3. 3. The IF steel clean smelting continuous casting method for the automobile based on rare earth microalloying according to claim 1, wherein the addition amount of the high-purity rare earth metal is 100-200 ppm.
4. 4. The IF steel clean smelting continuous casting method for the automobile based on rare earth micro-alloying of claim 1, wherein the rare earth oxysulfide with the size of less than or equal to 5 μm in the rare earth modified product accounts for more than or equal to 93 percent by mass.
5. 5. The method for clean smelting and continuous casting of the IF steel for the automobile based on rare earth microalloying according to claim 1, wherein the area ratio of inclusions in the steel is less than or equal to 0.02 percent, and the maximum size is less than or equal to 10 microns.
6. 6. The IF steel clean smelting continuous casting method for the automobile based on rare earth microalloying according to claim 1, wherein the plastic strain ratio r of the IF steel finished product is more than or equal to 2.23.

Description

IF steel clean smelting continuous casting method for automobile based on rare earth microalloying Technical Field The invention relates to the technical field of IF steel production, in particular to a clean smelting continuous casting method of IF steel for an automobile based on rare earth microalloying. Background IF steel (interstitial free steel) is an ultra low carbon steel, and by adding strong carbonitride forming elements such as titanium (Ti) and/or niobium (Nb), interstitial atoms (carbon and nitrogen) in the steel are completely fixed, thereby remarkably improving deep drawability and formability. The IF steel has excellent deep drawing performance, no timeliness (good formability after long-term storage) and high elongation, is not easy to crack when being punched, and is suitable for manufacturing parts with complex shapes. The method is widely applied to the automobile industry, the household appliance industry and the high-end packaging industry, and is especially a key material for the light weight and the complex part manufacture of modern automobiles. However, in the IF steel production process, coarse Al 2O3、Al2O3 +TiN composite inclusions and the like near the surface of the IF steel are easy to cause defects such as cracking, wrinkling and the like in the stamping process. The traditional production process realizes the spheroidization of the inclusions through calcium treatment to promote the denaturation and floating of the inclusions, and the problems that the Al 2O3 is incompletely denatured due to the calcium treatment and the size of the inclusions is difficult to control stably are easily caused by the factors of unstable calcium yield and the like when the method is adopted. Therefore, the technological process of RE treatment to improve inclusion is optimized, and the RE burning loss caused by fluctuation of liquid oxygen content (T [ O ]) in RE treatment is serious, so that RE oxide (REAlO 3) in large size is produced to deteriorate steel quality, resulting in high continuous casting nozzle nodulation risk and insufficient industrial production stability. In addition, the regulation and control mechanism of the current rare earth on texture evolution is not clear, so that the deep drawing performance (such as a plastic strain ratio r value) is limited. Disclosure of Invention The invention provides an IF steel clean smelting continuous casting method for an automobile based on rare earth microalloying, which realizes refining and dispersing of inclusions, improves deep drawing performance and improves stability of industrial production by optimizing rare earth adding technology and oxygen content control. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: the clean smelting continuous casting method of the IF steel for the automobile based on rare earth microalloying comprises the following steps: 1) Preparing high-purity rare earth metal: The oxygen content of the high-purity rare earth metal is less than 60ppm, the total impurity amount is less than 500ppm, and the blocking degree is less than or equal to 50mm; 2) Double hypoxia refining: controlling LF refining end point according to mass ratio, where T O is less than or equal to 20ppm, T S is less than or equal to 60ppm, white slag time is more than or equal to 20min; The RH refining deep vacuum degree is less than or equal to 100Pa, the deep vacuum holding time is more than or equal to 3min, and the deep vacuum circulation time after adding high-purity rare earth metal is more than or equal to 10min; Alloying in stages: The method is carried out according to the sequence of aluminum deoxidation, mn/Ti microalloying and rare earth addition, specifically comprises the steps of aluminum deoxidation for more than 3min, controlling Tal to be 0.03% -0.05% according to the mass ratio, adding Mn and sponge Ti for microalloying for more than 3min, and then adding high-purity rare earth metal through an RH high-level bin; 4) And (3) anti-oxidation pouring: The continuous casting adopts argon seal protection, the argon flow between the tundish and the crystallizer is 10-150L/min, and the nitrogen absorption amount in the whole process is less than 5ppm. The high-purity rare earth metal is high-purity lanthanum cerium rare earth metal. The addition amount of the high-purity rare earth metal is 100-200 ppm. In the rare earth modified product, the mass ratio of rare earth oxysulfide with the size less than or equal to 5 mu m is more than or equal to 93 percent. The area ratio of inclusions in the steel is less than or equal to 0.02 percent, and the maximum size is less than or equal to 10 mu m. The plastic strain ratio r value of the IF steel finished product is more than or equal to 2.23. Compared with the prior art, the invention has the beneficial effects that: 1) Suppressing the formation of rare earth oxide by "double hypoxia" control (molten steel T <30ppm, rare earth me