Method for steelmaking by replacing chromium alloy with chromite sand

Abstract

The invention relates to the technical field of steelmaking methods, and provides a steelmaking method using chromite sand to replace chromium alloy, which comprises the following steps: S1, smelting ferrosilicon alloy, scrap steel and foundry returns, adding chromite sand, and continuing smelting to obtain molten steel; s2, a nucleating agent is added into the molten steel for inoculation treatment, casting forming and heat treatment are conducted, and steel is obtained; the mass content of Cr2O3 in the chromite sand is greater than or equal to 45%; the nucleating agent is prepared from, by mass, 5%-30% of V, 10%-12% of Ce, 20%-35% of Lu, 0.5%-1% of Mn and the balance Fe and inevitable impurities. Through the technical scheme, the problems of high cost of chromium alloy and low strength of steel obtained by using the chromium alloy as a steelmaking raw material in related technologies are solved.

Description

Technical Field

[0001] The invention relates to the technical field of steelmaking methods, and in particular to a method for making steel by using chromite ore instead of chromium alloy. Background Art

[0002] With the continuous development of the steel industry, during industrial smelting, more chromium alloys are added to the ladle before use. At present, under the influence of the international and domestic economic situation, the price of chromium alloys continues to rise due to demand and cost factors. It is possible to study and find other materials containing high-value alloy elements to replace the use of micro-chromium alloys to reduce the cost of smelting materials. At the same time, the strength of the steel obtained after the addition of chromium alloys is low, which is difficult to meet the increasing application needs. Since the cost of chromite ore is low, a method of steelmaking with chromite ore instead of chromium alloys can be developed to ensure the improvement of the quality of molten steel, which is of great significance to reducing costs and improving economic benefits. Summary of the invention

[0003] The present invention provides a method for making steel by using chromite ore instead of chromium alloy, which solves the problems of high cost of chromium alloy and low strength of steel obtained as steelmaking raw material in the related art.

[0004] The technical solution of the present invention is as follows: The present invention provides a method for making steel by using chromite ore instead of chromium alloy, comprising the following steps: S1, smelting ferrosilicon alloy, scrap steel and recycled materials, adding chromite ore and continuing smelting to obtain molten steel; S2, adding an inoculant to the molten steel for inoculation treatment, casting and heat treatment to obtain a steel material; The mass content of Cr2O3 in the chromite ore is ≥45%; The inoculant consists of the following components in mass percentage: V 5%-30%, Ce 10%-12%, Lu 20%-35%, Mn 0.5%-1%, and the balance is Fe and inevitable impurities.

[0005] As a further technical solution, the mass ratio of V, Ce and Lu is 1:2:1~3.

[0006] In the present invention, the mass ratio of the components V, Ce and Lu of the inoculant is adjusted to 1:2:1-3, which further improves the strength and corrosion resistance of the steel.

[0007] As a further technical solution, the method for preparing the inoculant comprises the following steps: weighing alloy raw materials, performing vacuum melting, cooling, and crushing to obtain the inoculant.

[0008] As a further technical solution, the particle size of the inoculant is 100-150 μm.

[0009] As a further technical solution, the amount of the inoculant added is 0.3% to 0.8% of the mass of the molten steel.

[0010] As a further technical solution, the mass ratio of the ferrosilicon alloy, scrap steel, recycled materials and chromite ore is 15:10:450~540:280~410.

[0011] In the present invention, when the mass ratio of ferrosilicon alloy, scrap steel, recycled materials and chromite sand is 15:10:450-540:280-410, the strength and corrosion resistance of the steel are further improved.

[0012] As a further technical solution, during the heat treatment, the temperature is first raised to 1050-1090°C at a heating rate of 50-120°C / h, kept at that temperature for 2-4 hours, and then cooled to room temperature with the furnace at a cooling rate of 80-130°C / h.

[0013] As a further technical solution, during the heat treatment, the temperature is first raised to 1050-1090°C at a heating rate of 60-80°C / h, kept at that temperature for 2-4 hours, and then cooled to room temperature with the furnace at a cooling rate of 100-120°C / h.

[0014] In the present invention, the temperature is firstly increased to 1050-1090°C at a heating rate of 60-80°C / h, kept at this temperature for 2-4h, and then cooled to room temperature with the furnace at a cooling rate of 100-120°C / h, thereby further improving the strength and corrosion resistance of the steel.

[0015] As a further technical solution, the Si mass content of the ferrosilicon alloy is 70% to 80%.

[0016] As a further technical solution, the mass ratio of the ferrosilicon alloy, scrap steel, recycled materials and chromite ore is 15:10:500~510:300~400.

[0017] The working principle and beneficial effects of the present invention are: In the present invention, chromite ore is used to replace chromium alloy for steelmaking, and the components of the inoculant include V, Ce, Lu and Mn, which synergistically enhance the strength of the steel after steelmaking and also improve the corrosion resistance of the steel. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Example 1 The method for making steel by using chromite ore instead of chromium alloy comprises the following steps: S1, smelting ferrosilicon alloy, scrap steel and recycled materials, adding chromite ore and continuing smelting to obtain molten steel; S2, adding an inoculant to the molten steel for inoculation treatment, casting and heat treatment to obtain steel; The mass content of Cr2O3 in chromite ore is 46%; The inoculant is composed of the following components in mass percentage: V 5%, Ce 10%, Lu 20%, Mn 0.5%, and the balance is Fe and inevitable impurities; The mass ratio of ferrosilicon alloy, scrap steel, recycled materials and chromite is 15:10:450:280; During the heat treatment, the temperature was first raised to 1090°C at a heating rate of 50°C / h, kept at that temperature for 4 hours, and then cooled to room temperature in the furnace at a cooling rate of 130°C / h.

[0020] Example 2 The method for making steel by using chromite ore instead of chromium alloy comprises the following steps: S1, smelting ferrosilicon alloy, scrap steel and recycled materials, adding chromite ore and continuing smelting to obtain molten steel; S2, adding an inoculant to the molten steel for inoculation treatment, casting and heat treatment to obtain steel; The mass content of Cr2O3 in chromite ore is 50%; The inoculant is composed of the following components in mass percentage: V 30%, Ce 12%, Lu 35%, Mn 1%, and the balance is Fe and inevitable impurities; The mass ratio of ferrosilicon alloy, scrap steel, recycled materials and chromite sand is 15:10:540:410; During heat treatment, the temperature is first raised to 1050°C at a heating rate of 120°C / h, kept at that temperature for 2h, and then cooled to room temperature in the furnace at a cooling rate of 80°C / h.

[0021] Example 3 The method for making steel by using chromite ore instead of chromium alloy comprises the following steps: S1, smelting ferrosilicon alloy, scrap steel and recycled materials, adding chromite ore and continuing smelting to obtain molten steel; S2, adding an inoculant to the molten steel for inoculation treatment, casting and heat treatment to obtain steel; The mass content of Cr2O3 in chromite ore is 48%; The inoculant is composed of the following components in mass percentage: V 25%, Ce 11%, Lu 28%, Mn 0.6%, and the balance is Fe and inevitable impurities; The mass ratio of ferrosilicon alloy, scrap steel, recycled materials and chromite is 15:10:450:410; During heat treatment, the temperature was first raised to 1050°C at a heating rate of 50°C / h, kept at that temperature for 4 hours, and then cooled to room temperature in the furnace at a cooling rate of 130°C / h.

[0022] Example 4 The only difference between this embodiment and embodiment 3 is that the mass ratio of ferrosilicon alloy, scrap steel, recycled materials and chromite ore is 15:10:540:410.

[0023] Example 5 The only difference between this embodiment and embodiment 4 is that the mass ratio of ferrosilicon alloy, scrap steel, recycled materials and chromite sand is 15:10:500:300.

[0024] Example 6 The only difference between this embodiment and embodiment 4 is that the mass ratio of ferrosilicon alloy, scrap steel, recycled materials and chromite ore is 15:10:510:400.

[0025] Example 7 The only difference between this embodiment and embodiment 6 is that during heat treatment, the temperature is first raised to 1050°C at a heating rate of 120°C / h, kept at that temperature for 4 hours, and then cooled to room temperature in the furnace at a cooling rate of 80°C / h.

[0026] Example 8 The only difference between this embodiment and embodiment 6 is that during heat treatment, the temperature is first raised to 1050°C at a heating rate of 60°C / h, kept at that temperature for 4 hours, and then cooled to room temperature in the furnace at a cooling rate of 120°C / h.

[0027] Example 9 The only difference between this embodiment and embodiment 6 is that during heat treatment, the temperature is first raised to 1050°C at a heating rate of 80°C / h, kept at that temperature for 4 hours, and then cooled to room temperature in the furnace at a cooling rate of 100°C / h.

[0028] Example 10 The only difference between this embodiment and embodiment 9 is that the inoculant consists of the following components in mass percentage: V 5%, Ce 10%, and Lu 15%.

[0029] Embodiment 11 The only difference between this embodiment and embodiment 9 is that the inoculant consists of the following components in mass percentage: V 10%, Ce 10%, and Lu 20%.

[0030] Comparative Example 1 The difference between this comparative example and Example 1 is that Ce is not added.

[0031] Comparative Example 2 The difference between this comparative example and Example 1 is only that no Lu is added.

[0032] The steels prepared in Examples 1 to 11 and Comparative Examples 1 to 2 were respectively subjected to performance tests, and the tensile strength test (longitudinal) was carried out in accordance with the standard GB / T 228.1-2021 “Tensile test of metallic materials - Part 1: Room temperature test method”. The experiment was carried out using a YWST-86 salt spray test apparatus, and the experimental process was set as follows: spraying for 15 minutes at an interval of 15 minutes, and the spray medium was a NaCl solution with a concentration of 10wt%. The corrosion condition of the sample surface was observed, and the time when corrosion began to appear on the sample surface was recorded.

[0033] The test results are shown in Table 1 below.

[0034] Table 1 Performance test results

[0035] Compared with Comparative Examples 1-2, the steels prepared in Examples 1-11 have higher strength and longer salt spray resistance time, indicating that chromite ore is used instead of chromium alloy for steelmaking, and the components of the inoculant include V, Ce, Lu, and Mn, which synergistically enhance the strength of the steel after steelmaking and also improve the corrosion resistance of the steel.

[0036] Compared with Examples 3 to 4, the steels prepared in Examples 5 to 6 have higher strength and longer salt spray resistance time. When the mass ratio of ferrosilicon alloy, scrap steel, recycled materials and chromite sand is 15:10:450-540:280-410, the strength and corrosion resistance of the steels are further improved.

[0037] Compared with Examples 6 to 7, the steel obtained in Examples 8 to 9 has higher strength and longer salt spray resistance time, indicating that the steel is first heated to 1050 to 1090°C at a heating rate of 60 to 80°C / h, kept warm for 2 to 4 hours, and then cooled to room temperature with the furnace at a cooling rate of 100 to 120°C / h, thereby further improving the strength and corrosion resistance of the steel.

[0038] Compared with Example 9, the steels prepared in Examples 10 to 11 have higher strength and longer salt spray resistance time, indicating that adjusting the mass ratio of the components V, Ce, and Lu of the inoculant to 1:2:1 to 3 further improves the strength and corrosion resistance of the steel.

[0039] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for making steel using chromite ore instead of chromium alloy, characterized in that: The following steps are involved: S1, smelting ferrosilicon alloy, scrap steel and recycled materials, adding chromite ore and continuing smelting to obtain molten steel; S2, adding an inoculant to the molten steel for inoculation treatment, casting and heat treatment to obtain a steel material; The mass content of Cr2O3 in the chromite ore is ≥45%; The inoculant consists of the following components in mass percentage: V 5%-30%, Ce 10%-12%, Lu 20%-35%, Mn 0.5%-1%, and the balance is Fe and inevitable impurities.

2. The method for making steel by using chromite ore instead of chromium alloy according to claim 1, characterized in that: The mass ratio of V, Ce and Lu is 1:2:1-3.

3. The method for making steel by using chromite ore instead of chromium alloy according to claim 1, characterized in that: The preparation method of the inoculant comprises the following steps: weighing alloy raw materials, performing vacuum melting, cooling, and crushing to obtain the inoculant.

4. The method for making steel by using chromite ore instead of chromium alloy according to claim 1, characterized in that: The particle size of the inoculant is 100-150 μm.

5. The method for making steel by using chromite ore instead of chromium alloy according to claim 1, characterized in that: The amount of the inoculant added is 0.3% to 0.8% of the mass of the molten steel.

6. The method for making steel by using chromite ore instead of chromium alloy according to claim 1, characterized in that: The mass ratio of the ferrosilicon alloy, scrap steel, recycled materials and chromite ore is 15:10:450-540:280-410.

7. The method for making steel by using chromite ore instead of chromium alloy according to claim 1, characterized in that: During the heat treatment, the temperature is first raised to 1050-1090° C. at a heating rate of 50-120° C. / h, kept at that temperature for 2-4 hours, and then cooled to room temperature in the furnace at a cooling rate of 80-130° C. / h.

8. The method for making steel by using chromite ore instead of chromium alloy according to claim 7, characterized in that: During the heat treatment, the temperature is first raised to 1050-1090° C. at a heating rate of 60-80° C. / h, kept at that temperature for 2-4 hours, and then cooled to room temperature along with the furnace at a cooling rate of 100-120° C. / h.

9. The method for making steel by using chromite ore instead of chromium alloy according to claim 1, characterized in that: The Si mass content of the ferrosilicon alloy is 70% to 80%.

10. The method for making steel by using chromite ore instead of chromium alloy according to claim 6, characterized in that: The mass ratio of the ferrosilicon alloy, scrap steel, recycled materials and chromite ore is 15:10:500-510:300-400.

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