A method of smelting a tin-containing steel with uniform composition distribution

Abstract

The application discloses a smelting method of tin-containing steel with uniform component distribution, and belongs to the technical field of tin-containing steel smelting. The method comprises furnace charging, vacuum heating, refining degassing, alloying and tapping and pouring processes. The refining degassing process is carried out under high vacuum degassing with a vacuum degree of less than or equal to 1 Pa, and carbon powder is added in the later stage of refining; before the refining is completed, metal aluminum and metal tin are sequentially added. In the alloying process, the vacuum pump is stopped, high-purity argon is filled into the furnace, and then the required alloy is added into the molten steel. In the tapping and pouring process, the tapping temperature is controlled to be 30-50 DEG C higher than the liquidus, metal zirconium is added before tapping, and then high-power stirring is carried out to prepare for tapping. The round ingot mold with a wall thickness of 0.4-0.5 times of the inner diameter of the ingot mold is selected. The tin-containing steel cast blank obtained by the smelting method has uniform component distribution, and can be used as a direct-reading spectroscopy standard steel.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tin-containing steel smelting, and particularly relates to a smelting method of tin-containing steel with uniform component distribution. BACKGROUND

[0002] In the steel industry, tin has always been a harmful impurity element in steel, which affects the quality of steel, especially the quality of continuous casting billets, causes thermal embrittlement and temper embrittlement of steel, produces cracks and fractures, and affects the welding performance of steel, and is one of the "five evils" of steel. However, tin plays an important role in electrical steel, cast iron and free-cutting steel, and needs to be added in the smelting process, so it is necessary to quickly detect the tin element in the smelting process of such steel, and a straight reading spectrometer is used as a steel element quick detection device. In order to accurately detect the content of tin in steel, a tin-containing steel standard sample matched therewith must be provided.

[0003] In the smelting process of tin-containing steel, tin is a surface active element with typical grain boundary segregation characteristics. It has small solubility, large density and low melting point in the matrix, and will be enriched in the grain boundary zone in the form of low melting point eutectic. Although the content of tin in the whole steel and alloy is relatively low, the concentration at the grain boundary is several times or even dozens of times of the average content, resulting in uneven distribution of tin element in the ingot. Therefore, in the smelting of tin-containing steel, especially tin-containing straight reading spectrum standard steel, the key lies in the uniformity control of each element including tin element. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a smelting method of tin-containing steel with uniform component distribution, so as to smelt tin-containing steel with uniform components, which can be used as straight reading spectrum standard steel.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0006] A smelting method of tin-containing steel with uniform component distribution, comprising the processes of furnace charging, vacuum heating, refining and degassing, alloying and tapping and pouring.

[0007] The refining and degassing process is carried out under a vacuum degree of ≤1 Pa, and carbon powder is added in the later stage of refining to fully exert the vacuum carbon deoxidization capacity. Before the end of refining, metal aluminum and tin are sequentially added.

[0008] The alloying process is as follows: stop the vacuum pump, fill high-purity argon gas into the furnace, and then add the required alloy into the molten steel.

[0009] The tapping and pouring process is as follows: control the tapping temperature to be 30-50 ℃ above the liquidus, add metal zirconium before tapping, and then prepare for tapping by high-power stirring.

[0010] The ingot mold is selected to be a round ingot mold with a wall thickness of 0.4-0.5 of the inner diameter of the ingot mold.

[0011] Further, the alloying process of the present application is filled with 10000Pa-20000Pa high-purity argon.

[0012] Further, the alloying process of the present application is filled with 10000Pa-20000Pa high-purity argon.

[0013] Further, the alloying process of the present application is filled with 10000Pa-20000Pa high-purity argon.

[0014] Further, the alloying process of the present application is filled with 10000Pa-20000Pa high-purity argon.

[0015] Further, the alloying process of the present application is filled with 10000Pa-20000Pa high-purity argon.

[0016] The beneficial effects produced by the above technical solution are: in the refining and degassing period, the present application makes full use of the vacuum carbon deoxidation capacity, adds aluminum for deep deoxidation under the condition of ensuring low gas content in the steel, realizes low oxygen control of the molten steel, then fills argon in the alloying process, greatly improves the control precision of each component in the steel. Since Sn element is easy to segregate along the grain boundary during solidification, metal zirconium is added before tapping, so that high melting point Zr x Sn y compound is formed with tin, thereby changing the precipitation conditions and eliminating the grain boundary segregation of tin; low superheat pouring is used in the pouring process, and high-power stirring is used before pouring, and a round ingot mold with a wall thickness of 0.4-0.5 of the inner diameter of the ingot mold is used, so that the molten steel has more uniform composition distribution and finer grain size during solidification under the premise of ensuring sufficient feeding of the molten steel. DETAILED DESCRIPTION

[0017] The present application will be further described in detail below in combination with specific examples.

[0018] Examples 1-3: The smelting method of the tin-containing steel with uniform composition distribution uses the following specific process.

[0019] The equipment uses a 500kg vacuum induction furnace, the smelting composition is shown in Table 2, and the smelting weight is 500kg.

[0020] (1) Charging: Put pure iron into the crucible, and then put aluminum particles, metal tin, electrolytic manganese, industrial silicon and metal chromium into the material bin in sequence, ensuring that the alloying materials are dry and free of moisture.

[0021] (2) Vacuum heating: vacuumize and send power to heat until the pure iron in the crucible is completely melted.

[0022] (3) Refining degassing: high vacuum degassing is carried out under a vacuum degree of ≤1 Pa, and carbon powder is added in the later stage of refining. Before the end of refining, metal aluminum and metal tin are added in sequence.

[0023] (4) Alloying: after the end of the refining stage, the vacuum pump is stopped, the furnace is filled with 10000 Pa-20000 Pa high-purity argon, and electrolytic manganese, industrial silicon and metal chromium are added into the molten steel. After the addition, the temperature of the molten steel is controlled at 80-100°C above the liquidus, and the time is controlled at 5-15 min.

[0024] (5) Tapping and pouring process: after the composition of the molten steel is qualified, the tapping temperature is controlled at 30-50°C above the liquidus. Before tapping, metal zirconium is added at 10%-15% of the target tin content. After the addition, high-power stirring is carried out for 3-5 min to prepare for tapping.

[0025] The parameter control of each stage in the smelting process is shown in Table 1. After the ingot is demolded, forging is carried out, and the specification after forging is φ50 mm. Straight reading spectroscopy detection is carried out on the edge, center and 1 / 2R of the cross section of the forged rod. The detection results are shown in Table 2.

[0026] Table 1, parameter control of each stage in the smelting process of examples 1-3

[0027]

[0028] Note: TL is the liquidus temperature of the steel grade.

[0029] Table 2, chemical composition of smelted steel and straight reading detection results after forging of examples 1-3 (wt%)

[0030]

[0031] In Table 2, the balance is Fe and unavoidable impurities.

[0032] Examples 4-6: The smelting method of the tin-containing steel with uniform composition distribution adopts the following specific process.

[0033] The equipment uses a 200 kg vacuum induction furnace, and the smelting composition is shown in Table 4. The smelting weight is 200 kg.

[0034] (1) Charging: pure iron is placed in the crucible, and aluminum particles, metal tin, electrolytic manganese and phosphorus iron are sequentially charged into the material bin, ensuring that the alloy material is dry and free of moisture.

[0035] (2) Vacuum heating: vacuum is drawn, and power is sent to heat until the pure iron in the crucible is completely melted.

[0036] (3) Refining degassing: high vacuum degassing is carried out under a vacuum degree of ≤1 Pa, and carbon powder is added in the later stage of refining. Before the end of refining, metal aluminum and metal tin are added in sequence.

[0037] (4) Alloying: After the end of the refining period, stop the vacuum pump, fill the furnace with 10,000 Pa to 20,000 Pa of high-purity argon, and then add electrolytic manganese and phosphorus iron into the molten steel. After the addition, control the temperature of the molten steel to be 80°C to 100°C above the liquidus, and control the time to be 5 to 15 minutes.

[0038] (5) Tapping and pouring process: After the composition of the molten steel is detected to be qualified, control the tapping temperature to be 30°C to 50°C above the liquidus, and add metal zirconium according to 10% to 15% of the target tin content before tapping. After the addition, prepare for tapping by high-power stirring for 3 to 5 minutes.

[0039] The parameter control of each stage in the smelting process is shown in Table 3. After the ingot is demolded, forging is performed, and the specification after forging is φ50 mm. Straight reading spectroscopy is performed on the section edge, center, and 1 / 2R of the rod after forging, and the detection results are shown in Table 4.

[0040] Table 3, parameter control of each stage in the smelting process of Examples 4-6

[0041]

[0042] Note: TL is the liquidus temperature of the steel grade.

[0043] Table 4, chemical composition of the smelted steel and straight reading detection results after forging of Examples 4-6 (wt%)

[0044]

[0045] In Table 4, the balance is Fe and unavoidable impurities.

[0046] Examples 7-9: A smelting method of tin-containing steel with uniform composition distribution uses the following specific process.

[0047] The equipment uses a 50 kg vacuum induction furnace, and the smelted composition is shown in Table 6. The smelting weight is 50 kg.

[0048] (1) Charging: Put pure iron into the crucible, and then put aluminum particles, metal tin, electrolytic manganese, industrial silicon, and electrolytic copper into the material bin in sequence, ensuring that the alloy materials are dry and free of moisture.

[0049] (2) Vacuum heating: After vacuumizing, send power to heat until the pure iron in the crucible is completely melted.

[0050] (3) Refining and degassing: High-vacuum degassing is performed under a vacuum degree of ≤1 Pa, and carbon powder is added during the later refining period. Before the end of refining, metal aluminum and metal tin are added in sequence.

[0051] (4) Alloying: after the end of the refining period, stop the vacuum pump, fill the furnace with 10000Pa-20000Pa high-purity argon, then add electrolytic manganese, industrial silicon and electrolytic copper into the molten steel, control the temperature of the molten steel at 80-100℃ above the liquidus line after the addition, and control the time at 5-15min.

[0052] (5) Tapping and pouring process: after the composition of the molten steel is detected to be qualified, control the tapping temperature at 30-50℃ above the liquidus line, add metal zirconium according to 10-15% of the target tin content before tapping, and then prepare for tapping after high-power stirring for 3-5min.

[0053] The parameter control of each stage in the smelting process is shown in Table 5, the ingot is demolded after forging, the specification after forging is φ50mm, the straight reading spectrum detection is carried out on the section edge, center and 1 / 2R of the rod after forging, and the detection results are shown in Table 6.

[0054] Table 5, parameter control of each stage in the smelting process of examples 7-9

[0055]

[0056] Note: TL is the liquidus temperature of the steel grade.

[0057] Table 6, chemical composition of the smelted steel and the straight reading detection results after forging of examples 7-9 (wt%)

[0058]

[0059]

[0060] In Table 6, the balance is Fe and inevitable impurities.

[0061] As shown in Tables 2, 4 and 6, the uniformity control of each element in the tin-containing steel is realized.

Claims

1. A method for smelting tin-containing steel with uniform composition distribution, characterized in that, It includes the processes of charging the furnace, vacuum heating, refining and degassing, alloying and tapping and casting. The smelting method is applicable to the smelting of tin-containing steel with Sn ≤ 0.1 wt%. Refining and degassing process: High vacuum degassing is carried out under a vacuum degree ≤1Pa, and carbon powder is added in the later stage of refining. Before the end of refining, metallic aluminum and metallic tin are added in sequence. Alloying process: After stopping the vacuum pump and filling the furnace with high-purity argon gas, the required alloy is added to the molten steel. Steel tapping and casting process: control the tapping temperature at 30℃~50℃ above the liquidus line. Before tapping, add metallic zirconium at 10%~15% of the target tin content, and then stir at high power for 3min~5min to prepare for tapping. For casting, a round ingot mold with a wall thickness of 0.4 to 0.5 mm of the inner diameter of the ingot mold should be selected.

2. The method for smelting tin-containing steel with uniform composition distribution according to claim 1, characterized in that, During the alloying process, the furnace is filled with high-purity argon gas at 10000Pa to 20000Pa.

3. The method for smelting tin-containing steel with uniform composition distribution according to claim 2, characterized in that, In the alloying process, after adding the alloy, the temperature of the molten steel is controlled at 80°C to 100°C above the liquidus line, and the time is controlled at 5 to 15 minutes.

4. The method for smelting tin-containing steel with uniform composition distribution according to claim 1 or 2, characterized in that, The smelting method is applicable to vacuum furnaces and induction furnaces with a furnace capacity of ≤500kg.

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