Preparation method of Ce-containing girder steel

Abstract

The invention discloses a preparation method of Ce-containing girder steel, and belongs to the technical field of ferrous metallurgy. Comprising the following steps: 1) smelting test steel by adopting a vacuum induction furnace; (2) a girder steel plate is adopted as a raw material; (3) CeFe alloy with high cleanliness is used; (4) all the raw materials are added into a crucible to be smelted, and it is guaranteed that smelting is conducted in a vacuum state; (5) after the raw materials are melted for 0.8-1.5 min, the calculated rare earth cerium iron alloy is added; (6) casting under vacuum after ensuring that the rare earth cerium-iron alloy is completely melted; and (7) chemical components of the smelted steel grade are inspected, and it is guaranteed that the chemical components are the same as or similar to target components. The purpose of stably controlling the oxygen content and the Ce content in the steel through the vacuum induction furnace is achieved, the types, the sizes and the like of inclusions in the girder steel are improved, and then the comprehensive performance of the girder steel is improved. And meanwhile, technical support is provided for stably controlling the content of rare earth Ce in steel in industrial production.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy technology, and particularly relates to a method for preparing Ce-containing beam steel. Background Technology

[0002] In recent years, significant progress has been made in the application of rare earth elements in steel, and in-depth and detailed research has been conducted on their mechanisms of action in steel, yielding substantial advancements. The research and application of high-strength automotive frame steel sheets have attracted increasing attention. The steel market urgently needs high-strength, stable-performance automotive steel sheets. To meet and address domestic demand for high-strength automotive frame steel, and to provide stable and high-quality products while keeping pace with international developments, the gradual development of high-strength automotive frame steel has become imperative. Rare earth elements can improve the cleanliness of steel, reduce inclusion content, and enhance overall performance. Therefore, researching the stable addition of rare earth elements to frame steel is an effective method.

[0003] Chinese Patent Application No. 201210192278.4 discloses an improved method for preparing 30CrMnSi steel. The method involves melting steel in a medium-frequency coreless induction furnace, using steel as the main raw material, and adding appropriate amounts of ferrochrome, ferromanganese, ferrosilicon, ferroboron, rare earth alloys for alloying. Standard wedge-shaped and trapezoidal specimen blanks are cast using clay sand and a wet mold. The specimens are then annealed. The resulting 30CrMnSi steel is austenitized by holding it at approximately 840℃ for 550–600 seconds, followed by isothermal quenching or incomplete quenching at 180–300℃ for 300–500 seconds, and finally quenching to room temperature. This yields a high-performance 30CrMnSi steel that maintains high strength while also possessing a certain degree of plasticity, and its overall mechanical properties are significantly improved compared to traditional heat treatment processes.

[0004] Chinese Patent Application No. 202111603756.1 discloses a method for preparing mold steel based on powder metallurgy. The method includes the following steps: cleaning and drying of raw materials; weighing and proportioning of raw materials; inert gas atomization powder preparation; recovery of separated gases; hot isostatic pressing; and precision forging. The advantages of this method are that inert gas atomization powder preparation and hot isostatic pressing are used in the preparation of the mold steel. Simultaneously, before melting and refining, the raw materials undergo cleaning and drying processes to remove surface impurities, improving the precision of the mold steel. During powder collection, the separated gases can be recovered, avoiding direct discharge and waste; the collected gases can be reused later.

[0005] Chinese Patent Application No. 201410753437.2 discloses a method for preparing 304 austenitic stainless steel with a grain size of less than 100 nm. The method involves hot-rolling 304 austenitic stainless steel into a 4–5 mm thick sheet, resulting in an austenitic microstructure with a grain size of 18–20 μm and relatively uniform microstructure. This is followed by a three-stage cold rolling-annealing process to produce 304 austenitic stainless steel with a grain size of less than 100 nm. Mechanical property tests on the experimental steel revealed a yield strength of 1100–1200 MPa, nearly five times higher than the original yield strength, and a tensile strength of 1250–1350 MPa. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing Ce-containing beam steel to produce high-purity Ce-containing beam steel.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] This invention discloses a method for preparing Ce-containing beam steel, comprising:

[0009] 1) Vacuum induction furnace was used to smelt the test steel.

[0010] 2) Using steel plates and beams as raw materials for crushing and processing into long strips as furnace charge, stabilizing the composition and improving the hit rate;

[0011] 3) Using high-purity CeFe alloy, the amount of rare earth cerium iron alloy added is calculated based on the target composition with different Ce contents, so as to stably control the Ce content in the steel.

[0012] 4) Add all raw materials to the crucible for smelting, and ensure that the process is carried out under vacuum.

[0013] 5) Add the calculated rare earth cerium-iron alloy 0.8-1.5 minutes after the raw materials have melted;

[0014] 6) Ensure that the rare earth cerium-iron alloy is completely melted before casting under vacuum;

[0015] 7) Inspect the chemical composition of the smelted steel to ensure that it is the same as or similar to the target composition.

[0016] Furthermore, a 25kg vacuum induction furnace was used for smelting.

[0017] Furthermore, it is processed into long strips 25-35cm long and 2-4cm wide as furnace charge.

[0018] Furthermore, it is processed into strips 30cm long and 3cm wide as furnace charge.

[0019] Furthermore, the high-purity CeFe alloy has an O content of 80 ppm and an S content of 25 ppm.

[0020] Furthermore, 1 minute after the raw materials have melted, the calculated rare earth cerium-iron alloy is added.

[0021] Furthermore, smelting is carried out under vacuum conditions, with a vacuum level of 80-100 Pa.

[0022] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0023] This invention addresses the technical problems mentioned in the background by employing a vacuum induction furnace for testing. Current CeFe alloys have an O content of 120 ppm and a S content of 30 ppm, indicating low cleanliness and a high concentration of impurities. Using a high-cleanliness CeFe alloy allows for more stable control of the Ce content. Conventional CeFe alloys result in oxygen content in steel as high as 30 ppm, while the high-cleanliness CeFe alloy controls the oxygen content to an average of 25 ppm. This achieves stable control of oxygen and Ce content in steel using a vacuum induction furnace, improving the type and size of inclusions in beam steel and thus enhancing the overall performance of the beam steel. Simultaneously, it provides technical support for the stable control of rare earth Ce content in steel during industrial production. This analytical method is simple, effective, low-cost, and has broad application prospects. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings.

[0025] Figure 1 Results of improving inclusions in rare earth Ce-containing beam steel.

[0026] Figure 2 Results of improved overall performance of rare earth Ce-containing beam steel. Detailed Implementation

[0027] Case 1:

[0028] 1. The test steel was smelted in a 25kg vacuum induction furnace, and the rare earth Ce content of the test steel was required to be 50ppm.

[0029] 2. Use raw materials with a composition similar to the target steel grade for smelting. The specific composition is shown in the table below.

[0030]

[0031] 3. Based on the content of rare earth cerium-iron alloy and the yield, the amount of rare earth cerium-iron alloy added is calculated to be 17g.

[0032] 4. Ensure smelting is carried out under vacuum conditions, with a vacuum degree of 90 Pa.

[0033] 5. Add rare earth cerium-iron alloy 1 minute after the raw materials have melted.

[0034] 6. After heating for 2 minutes, ensure that the alloy is completely melted, and then cast under vacuum.

[0035] 7. The chemical composition of the smelted steel was tested. The O content was 24 ppm and the rare earth Ce content was 54 ppm, which is basically the same as the design target composition.

[0036] Case 2:

[0037] 1. The test steel was smelted in a 25kg vacuum induction furnace, and the rare earth Ce content of the test steel was required to be 100ppm.

[0038] 2. Use raw materials with a composition similar to the target steel grade for smelting. The specific composition is shown in the table below.

[0039]

[0040]

[0041] 3. Based on the content and yield of rare earth cerium-iron alloy, the amount of rare earth cerium-iron alloy added is calculated to be 31.7g.

[0042] 4. Ensure smelting is carried out under vacuum conditions, with a vacuum degree of 90 Pa.

[0043] 5. Add rare earth cerium-iron alloy 1 minute after the raw materials have melted.

[0044] 6. After heating for 2 minutes, ensure that the alloy is completely melted, and then cast under vacuum.

[0045] 7. The chemical composition of the smelted steel was tested. The O content was 26 ppm and the Ce content was 110 ppm, which is basically the same as the design target composition.

[0046] The effect of improving inclusions: Figure 1 a is the inclusion morphology of the blank sample. The inclusion size is relatively large, reaching more than 100 μm. Figure 1 b is a morphological image of the inclusions in Case 1, where the inclusions are relatively dispersed and small; Figure 1 c is the morphology image of the inclusions in Case 2. The inclusions are also diffuse and small. The improvement effect on inclusions is quite obvious.

[0047] Improvement effect on overall performance: Figure 2 The figures show the tensile properties of the blank sample and the samples from Case 1 and Case 2. As shown in the figure, the tensile strength, yield strength, and elongation were all improved after the addition of rare earth elements.

[0048] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing Ce-containing beam steel, characterized in that: include 1) Vacuum induction furnace was used to smelt the test steel. 2) Using steel plates and beams as raw materials for crushing and processing into long strips as furnace charge, stabilizing the composition and improving the hit rate; 3) Using high-purity CeFe alloy, the amount of rare earth cerium iron alloy added is calculated based on the target composition with different Ce contents, so as to stably control the Ce content in the steel. 4) Add all raw materials to the crucible for smelting, and ensure that the process is carried out under vacuum. 5) Add the calculated rare earth cerium-iron alloy 0.8-1.5 minutes after the raw materials have melted; 6) Ensure that the rare earth cerium-iron alloy is completely melted before casting under vacuum; 7) Inspect the chemical composition of the smelted steel to ensure that it is the same as or similar to the target composition.

2. The method for preparing Ce-containing beam steel according to claim 1, characterized in that: Smelting was carried out using a 25kg vacuum induction furnace.

3. The method for preparing Ce-containing beam steel according to claim 1, characterized in that: It is processed into long strips 25-35cm long and 2-4cm wide as furnace charge.

4. The method for preparing Ce-containing beam steel according to claim 3, characterized in that: It is processed into strips 30cm long and 3cm wide as furnace charge.

5. The method for preparing Ce-containing beam steel according to claim 1, characterized in that: The high-purity CeFe alloy has an O content of 80 ppm and an S content of 25 ppm.

6. The method for preparing Ce-containing beam steel according to claim 1, characterized in that: One minute after the raw materials have melted, the calculated rare earth cerium-iron alloy is added.

7. The method for preparing Ce-containing beam steel according to claim 1, characterized in that: Smelting is carried out under vacuum conditions, with a vacuum level of 80-100 Pa.

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