A method for producing a rapidly solidified iron-based alloy strip

Abstract

The application belongs to the technical field of alloy preparation, and discloses a preparation method of a rapidly solidified iron-based alloy strip, which comprises the following steps: weighing electrolytic iron, monocrystalline silicon, carbon powder and diiron trioxide, vacuum smelting, and repeatedly smelting and cooling to obtain a cast-state master alloy. The master alloy is cut and placed in a quartz tube, and is smelted and strip cast at specific parameters to prepare the rapidly solidified iron-based alloy strip. The parameters for preparing the Fe-O system strip sample are set as follows: the rotating speed of the copper wheel is 2050 r / min, the injection gas pressure is 0.002 MPa, and the distance from the nozzle to the copper wheel is 0.02 mm; the parameters for preparing the Fe-Si-C-O system strip sample are set as follows: the rotating speed of the copper wheel is 2400 r / min, the injection gas pressure is 0.004 MPa, and the distance from the nozzle to the copper wheel is 0.03 m, so that the accurate proportioning of alloy components is ensured, the rapid solidification of the alloy is realized by using the chilling strip casting function of the high-vacuum induction smelting strip caster, the alloy organization is significantly refined, the mechanical properties of the material are improved, the experience summary of the operator is not needed, and the standardization during production is improved.

Description

Technical Field

[0001] This invention belongs to the field of metal preparation technology, specifically relating to a method for preparing rapidly solidified iron-based alloy strips. Background Technology

[0002] Regarding how to alter the state of oxygen in steel, research has shown that rapid cooling can effectively suppress the precipitation of oxygen as oxide inclusions and promote the solidification of oxygen in the steel as atoms, thus increasing the dissolved oxygen content. However, due to technological limitations, current rapid cooling sample preparation methods are mostly limited to strips or small blocks, and researchers primarily focus on the preparation of multi-component medium and high alloy steel strips. Research on the preparation of low alloy steel strips under rapid cooling is relatively limited, and relevant process parameters have not yet been standardized, relying heavily on operator experience. Therefore, a rapid solidification method for preparing iron-based alloy strips is proposed to address these issues. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing rapidly solidified iron-based alloy strips, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing rapidly solidified iron-based alloy strip, comprising,

[0005] S1: Weigh the preset mass of electrolytic iron, single crystal silicon, carbon powder and ferric oxide using a precision balance;

[0006] S2: Load the material into a container, then place the container into the induction coil of the melting and spinning equipment, and evacuate the vacuum until the vacuum degree is less than 5×10. -5 Pa, stop evacuating and fill with argon gas for protection;

[0007] S3: Induction melting is performed through an induction coil. After the material inside the container is completely melted, the temperature is kept for a preset time. Then, the molten steel is poured into the mold through the operating rod. After cooling to room temperature, it is taken out. The vacuum chamber is always kept under argon protection before the sample is taken out.

[0008] S4: After repeating S2 to S3 three times, the material inside the mold forms a cast master alloy of Fe-Si-CO iron-based low alloy steel. Take 10g of the Fe-Si-CO cast master alloy and place it in a special quartz tube for strip casting. Then place the special quartz tube for strip casting in a melting and strip casting equipment for melting. The parameters for preparing the Fe-Si-CO strip sample are: copper wheel speed 2400r / min, injection air pressure 0.004MPa, and nozzle to copper wheel distance 0.03mm. The rapidly solidified Fe-Si-CO strip sample is prepared by using the quench strip casting function.

[0009] Preferably, the electrolytic iron has a mass percentage of 99.99%, the monocrystalline silicon has a mass percentage of 99.99%, the carbon powder has a mass percentage of 99.99%, and the ferric oxide has a mass percentage of 99.99%.

[0010] Preferably, the melting and spinning equipment has a maximum melting power of 35 KVA and an induction frequency of 30-80KHz.

[0011] Preferably, the melting and spinning equipment is a JVSM-2 type high vacuum induction melting and spinning machine.

[0012] Preferably, the precision balance has an accuracy of 0.0001 mg.

[0013] Preferably, the inner cavity dimensions of the mold are Ø20mm×70mm.

[0014] Preferably, in step S2, the argon protection pressure is -0.06 MPa.

[0015] Preferably, in step S3, the preset duration is five minutes.

[0016] Preferably, the container is a magnesium oxide crucible.

[0017] Preferably, the mold is a copper mold.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] This invention employs a high-precision balance to weigh raw materials and sets the parameters for preparing Fe-O ribbon samples as follows: copper wheel speed 2050 r / min, injection pressure 0.002 MPa, and nozzle-to-copper wheel distance 0.02 mm; and for preparing Fe-Si-CO ribbon samples, the parameters are set as follows: copper wheel speed 2400 r / min, injection pressure 0.004 MPa, and nozzle-to-copper wheel distance 0.03 m. This ensures precise alloy composition and utilizes the rapid solidification function of a high-vacuum induction melting and spinning machine to achieve rapid alloy solidification, significantly refine the alloy microstructure, and improve the mechanical properties of the material. This process eliminates reliance on operator experience and enhances standardization during production. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention;

[0021] Figure 2 This is a schematic diagram of the test results for the alloy composition distribution in this invention;

[0022] Figure 3 These are sample images under different injection pressures according to the present invention;

[0023] Figure 4These are sample images of the copper wheel of the present invention at different rotational speeds;

[0024] Figure 5 Images of strip samples obtained at different spraying distances according to the present invention;

[0025] Figure 6 This is a sample image of the strip obtained after the parameters were improved according to the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please see Figures 1-6 As shown, the present invention provides the following technical solution: a method for preparing rapidly solidified iron-based alloy strip, comprising:

[0028] S1: Weigh the predetermined mass of electrolytic iron, monocrystalline silicon, carbon powder, and ferric oxide using a precision balance with an accuracy of 0.0001 mg. In this invention, the mass percentages of electrolytic iron, monocrystalline silicon, carbon powder, and ferric oxide are 99.99%, 99.99%, 99.99%, and 99.99%, respectively. The low content of impurity elements in the electrolytic iron can effectively prevent the smelted master alloy from being affected by other elements. The smelted master alloy is proportioned in 200g increments.

[0029] S2: Load the material into the magnesium oxide crucible, then place the magnesium oxide crucible into the induction coil of the JVSM-2 high-vacuum induction melting and spinning machine, and evacuate the vacuum until the vacuum degree is less than 5×10. -5 Pa, stop evacuation and fill with argon gas for protection at a pressure of -0.06 MPa. Use a magnesium oxide crucible for melting, with a maximum capacity of 1000 g (based on iron). Magnesium oxide has a melting point of 2582℃, which is much higher than the melting point of iron (1538℃), effectively preventing the crucible from melting and introducing impurity elements during the melting process.

[0030] Furthermore, regarding the aforementioned JVSM-2 high-vacuum induction melting and spinning machine, the copper wheel of this equipment employs magnetohydrodynamic sealing technology, achieving a maximum rotational speed of 60 m / sec and a maximum cooling rate ≥106 K / sec. The cooling rate can be adjusted by regulating the copper wheel speed, heating current, and cooling water temperature. The thickness of the product produced by this equipment is 20~60 μm, the width is 1~10 mm, and the maximum melting temperature is ≥1600℃. The spinning test uses a dedicated quartz crucible with a 10 mm long and 3 mm wide narrow slit nozzle. The maximum sample size is 70 g (based on iron). The equipment also features an adjustable, water-cooled crucible support with an injection tilt angle adjustable within the range of 0-90°.

[0031] S3: Induction melting is performed using an induction coil. After the material inside the magnesium oxide crucible is completely melted, it is held at that temperature for five minutes. Then, the molten steel is poured into a copper mold through an operating rod. The inner cavity of the copper mold is Ø20mm×70mm. After cooling to room temperature, the sample is removed. The vacuum chamber is kept under argon protection until the sample is removed. Casting is performed using a copper mold. Copper has excellent thermal conductivity, which can effectively shorten the cooling time of the molten steel. To accommodate the size of the magnesium oxide crucible, the master alloy obtained in S3 needs to be processed. The sample is machined into a cylindrical specimen of Ø12×8 mm on a lathe. After removing surface defects from the master alloy, the surface of the test alloys is free of obvious defects. The surface of the Si-containing test alloy is relatively bright. Before the casting test, the ingot is ground to 1000# to remove the surface oxide film, cleaned with deionized water, degreased with acetone, and then quickly dried. To avoid the oxide film on the surface of the casting interfering with the oxygen addition of the alloy, the casting should be processed and used immediately after grinding and degreasing.

[0032] S4: After repeating S2 to S3 three times, the internal material of the copper mold forms Fe-Si-CO and Fe-O as-cast master alloys. 10 g of each Fe-Si-CO and Fe-O as-cast master alloy is taken and placed in a special quartz tube for strip spinning. The quartz tube is then placed in a JVSM-2 high-vacuum induction melting strip spinning machine for melting. The parameters for preparing the Fe-O strip sample are: copper wheel speed 2050 r / min, injection pressure 0.002 MPa, and nozzle-to-copper wheel distance 0.02 mm. The parameters for preparing the Fe-Si-CO strip sample are: copper wheel speed 2400 r / min, injection pressure 0.004 MPa, and nozzle-to-copper wheel distance 0.03 mm. mm thick, rapidly solidified Fe-Si-CO and Fe-O ribbon samples were prepared using a rapid cooling and spinning function. The Fe-O alloy exhibited numerous surface defects and poor surface finish, likely due to its high oxygen content and boiling state during melting, resulting in significant porosity. In contrast, the Fe-Si-CO alloy with 0.6 wt% single-crystal silicon showed a smoother surface without significant porosity or other defects. This is attributed to the deoxidizing effect of silicon and carbon, which helps to calm the alloy.

[0033] Furthermore, regarding the aforementioned JVSM-2 high-vacuum induction melting belt spinning machine, the maximum melting power of this equipment is 35KVA, and the induction frequency is 30-80KHz.

[0034] In addition, in this invention, to verify the uniformity of the composition distribution of the master alloy, compositional analysis was performed on the surface of the test alloy. EDS layered images are shown below. Figure 2 As shown: Except for carbon, which partially aggregates, the other components are uniformly distributed in the test alloy, and it can be considered that the uniformity of the master alloy prepared in the test meets the test requirements.

[0035] Furthermore, to investigate the effect of injection pressure, in this invention, the test alloy was heated in a quartz crucible by electromagnetic induction using an energized coil. The melting power was increased slowly from 0 kVA at a rate of 0.1 kVA. As the melting power increased, the molten steel was observed to glow red-hot and then emit a dazzling white light. After complete melting (approximately 1.5 kVA), the melting power was appropriately reduced to maintain the molten steel at a boiling point for 60 seconds. Argon gas was then introduced to apply pressure to the molten steel, allowing it to flow evenly from the nozzle and contact a copper wheel that was cooled by water and rotated at high speed. The steel cooled and solidified on the copper wheel and then detached from it under centrifugal force, entering the sampling chamber. Therefore, the injection pressure directly affects the contact speed between the molten steel and the copper wheel, and under a constant cooling rate, it has a significant impact on the cooling effect. Based on relevant research, this experiment used high-purity electrolytic iron as raw material, fixed the copper wheel speed at 3000 r / min and the distance from the nozzle to the copper wheel at 1 mm, and conducted cooling and spinning experiments under injection pressures of 0.04, 0.03, 0.02, 0.01, 0.005, and 0.002 MPa. The experimental results are as follows. Figure 3 As shown, Figure 3 The first image in the first row from the middle left is a sample image under a jet pressure of 0.04 MPa. Figure 3 The second image in the first row from the left in the middle is a sample image under a jet pressure of 0.03 MPa. Figure 3 The first image in the second row from the left in the middle is a sample image under a jet pressure of 0.02 MPa. Figure 3 The second image in the second row from the left in the middle is a sample image under a jet pressure of 0.01 MPa. Figure 3 The first image in the third row from the left in the middle is a sample image under a jet pressure of 0.005 MPa. Figure 3 The second image in the third row from the left in the middle is a sample image under a jet pressure of 0.002 MPa.

[0036] Depend on Figure 3 As can be seen, the injection pressure has a significant impact on the formability of the strip. When the injection pressure is 0.02~0.04 MPa, the high pressure prevents the molten steel from effectively contacting the copper wheel for cooling. Some molten steel even splashes directly into the vacuum chamber and onto the furnace wall, resulting in a bright red-hot appearance and poor cooling effect. The cooled samples are dot-shaped. Samples that come into contact with the copper wheel and enter the cooling chamber through a spinning motion are mostly powdery, exhibiting poor formability and continuity. With decreasing injection pressure, the formability of the pure iron strip samples improves significantly. Samples with an injection pressure of 0.002 MPa show strip-like characteristics, but these are mostly fragmented strips, and their width and thickness do not yet meet requirements, necessitating further improvement.

[0037] The above research results show that the injection pressure has a significant impact on the formability of pure iron strips under rapid cooling. The ideal conditions for strip preparation are as follows:

[0038] 1: Under a certain injection pressure, molten steel can be ejected at a relatively uniform rate, which is beneficial for producing good continuity in the strip.

[0039] 2: The cooling provided by the copper wheel per unit time is just enough to meet the cooling requirements of the sample volume in contact with the copper wheel;

[0040] 3: The contact time between molten steel and the copper wheel ensures that the molten steel is cooled and formed, and has good adhesion to subsequent samples.

[0041] Therefore, the magnitude of the injection pressure is closely related to the formability and continuity of the strip. Since alloys with different compositions exhibit significant differences in liquid flowability and cooling rates, the optimal injection pressure needs to be determined through trial and error based on specific alloy compositions.

[0042] Based on the above experimental results, the effect of different rotational speeds of the copper wheel on the preparation of pure iron strip samples was investigated under the condition of fixed nozzle distance and injection pressure. In the experiment, the nozzle distance was 0.1 mm, the injection pressure was 0.002 MPa, and the copper wheel rotational speeds were set to 1200, 1500, 1800, 2100, 2400, and 2700 r / min. The experimental results are as follows: Figure 4 As shown, Figure 4 The first image in the first row from the left is a sample image at a copper wheel speed of 1200 r / min. Figure 4 The second image in the first row from the left is a sample image at a copper wheel speed of 1500 r / min. Figure 4 The first image in the second row from the left in the middle is a sample image at a copper wheel speed of 1800 r / min. Figure 4 The second image in the second row from the left in the middle is a sample image at a copper wheel speed of 2100 r / min. Figure 4 The first image in the third row from the left in the middle is a sample image at a copper wheel speed of 2400 r / min. Figure 4 The second image in the third row from the left in the middle is a sample image at a copper wheel speed of 2700 r / min.

[0043] Based on the above experimental results, under the conditions of a fixed copper wheel rotation speed of 2100 r / min and a jet pressure of 0.002 MPa, the effect of the distance between the quartz crucible nozzle and the copper wheel, i.e., the jetting distance, on the preparation of pure iron strip samples was investigated. The experimental results are as follows: Figure 5 As shown, Figure 5 The spray distances are 3mm, 2mm, 1mm, 0.6mm, 0.4mm, and 0.2mm respectively.

[0044] As can be seen from the above, when the spray distance is 2mm~3mm, the sample appears as multiple small clumps with poor formability. This is because when the spray distance is large, the molten steel is prone to splashing on the surface of the copper wheel, thus interrupting the connection between samples and preventing the formation of a continuous strip. Continuously reducing the distance from the nozzle to the copper wheel significantly improves the formability and continuity of the sample. When the spray distance is 0.2mm~0.4mm, the sample is essentially formed into a strip, and the free surface of the sample exhibits a bright metallic luster. However, because the sample has not reached sufficient cooling when leaving the copper wheel under these parameters, sample accumulation and entanglement between strips are likely to occur during continued cooling in the sampling chamber. Further optimization and improvement of the relevant experimental parameters are needed.

[0045] Based on the above experiments, the experimental parameters were further optimized through repeated experiments. The optimal parameters for preparing high-purity electrolytic iron strip samples under rapid cooling were finally determined to be: copper wheel speed 2050 r / min, injection pressure 0.001 MPa, and injection distance 0.03 mm. Based on this experiment, strip samples of Fe-Si-CO and Fe-O iron-based low-alloy steels were prepared under rapid cooling. The parameters for preparing the Fe-O strip samples were: copper wheel speed 2050 r / min, injection pressure 0.002 MPa, and nozzle-to-copper wheel distance 0.02 mm; the parameters for preparing the Fe-Si-CO strip samples were: copper wheel speed 2400 r / min, injection pressure 0.004 MPa, and nozzle-to-copper wheel distance 0.03 mm. The prepared D1 and D6 strips are shown below. Figure 6 As shown, the sample has basically formed a strip, but some agglomeration still occurs. Relatively complete strips can be peeled off for electrochemical testing. To further improve the formability and integrity of the strip, the process parameters can be refined and improved by considering the influence of other factors on the strip preparation. Specifically, improvements can be made in the following two aspects:

[0046] (1) Consider reducing the temperature of the cooling medium. For example, adding industrial ice to the cooling water tank can effectively improve the cooling effect of the copper wheel and complete the cooling of the molten steel before it leaves the copper wheel.

[0047] (2) Design the composition of the material. For example, relevant studies have shown that adding element B can effectively reduce the driving force required for cooling steel.

[0048] As shown in the figure, when the rotation speed is 1200 and 1500 r / min, the sample tends to clump together. This is because the cooling provided by the copper wheel at low speeds is insufficient to ensure that the molten steel is completely cooled before leaving the copper wheel. Under the influence of centrifugal force, the sample flies out in a parabolic trajectory and accumulates in the sampling chamber. Observations during the experiment revealed a high temperature on the outer wall of the sampling chamber, which confirms this. When the rotation speed is 2400 and 2700 r / min, the samples are mostly powdery or leaf-shaped. This is because the cooling capacity provided by the copper wheel at high speeds exceeds the cooling required for the sample volume per unit time. Furthermore, at high speeds, the contact time between the molten steel and the copper wheel is shortened, and turbulence may even occur. The leaf-shaped samples are mostly due to the molten steel contacting the copper wheel in the form of small droplets, resulting in poor sample continuity. When the rotation speed is 1800 and 2400 r / min, the sample has good formability and continuity. In particular, when the rotation speed is 2100 r / min, the sample has some bands and the surface shows a metallic luster, but the continuity of the bands still needs to be improved.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing rapidly solidified iron-based alloy strip, characterized in that: include, S1: Weigh the preset mass of electrolytic iron, single crystal silicon, carbon powder and ferric oxide using a precision balance; S2: Load the material into the magnesium oxide crucible, then place the magnesium oxide crucible into the induction coil of the melting and spinning equipment, and evacuate the vacuum until the vacuum degree is less than 5×10. -5 Pa, stop evacuating and fill with argon gas for protection; S3: Induction melting is performed through an induction coil. After the material inside the magnesium oxide crucible is completely melted, the temperature is kept for a preset time. Then, the molten steel is poured into the copper mold through the operating rod. After cooling to room temperature, it is taken out. Before taking out the sample, the vacuum chamber is always kept under argon protection. S4: After repeating S2 to S3 three times, the material inside the copper mold forms a cast master alloy of Fe-Si-CO iron-based low alloy steel. Take 10g of the Fe-Si-CO cast master alloy and place it in a special quartz tube for strip casting. Place the special quartz tube for strip casting in a melting and strip casting equipment for melting. The parameters for preparing the Fe-Si-CO strip sample are: copper wheel speed 2400r / min, injection air pressure 0.004MPa, nozzle to copper wheel distance 0.03mm. Prepare a rapidly solidified Fe-Si-CO strip sample by using the quench strip casting function. The melting and strip casting equipment is a JVSM-2 type high vacuum induction melting and strip casting machine.

2. The method for preparing rapidly solidified iron-based alloy strip according to claim 1, characterized in that: The electrolytic iron has a mass percentage of 99.99%, the monocrystalline silicon has a mass percentage of 99.99%, the carbon powder has a mass percentage of 99.99%, and the ferric oxide has a mass percentage of 99.99%.

3. The method for preparing rapidly solidified iron-based alloy strip according to claim 1, characterized in that: The melting power of the melting and spinning equipment is up to 35 KVA, and the induction frequency is 30-80KHz.

4. The method for preparing rapidly solidified iron-based alloy strip according to claim 1, characterized in that: The precision balance has an accuracy of 0.0001 mg.

5. The method for preparing rapidly solidified iron-based alloy strip according to claim 1, characterized in that: The inner cavity dimensions of the mold are Ø20mm×70mm.

6. The method for preparing rapidly solidified iron-based alloy strip according to claim 1, characterized in that: In S2, the argon protection pressure is -0.06 MPa.

7. The method for preparing rapidly solidified iron-based alloy strip according to claim 1, characterized in that: In S3, the preset duration is five minutes.

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