Ultralow-oxygen high-nitrogen corrosion-resistant cutting tool steel and vacuum melting process thereof

Abstract

The invention provides ultralow-oxygen high-nitrogen corrosion-resistant cutting tool steel and a vacuum melting process thereof, and relates to the field of steel smelting. According to the scheme, the problems that the nitrogen content of the corrosion-resistant cutting tool steel is large in fluctuation and cannot be accurately controlled in vacuum induction melting are solved, a vacuum induction furnace is used for smelting in the process, proper raw material types and raw material adding time and mode are formulated, and the ultralow-oxygen high-nitrogen corrosion-resistant cutting tool steel is produced through three times of deoxidation in cooperation with a nitrogen control process; the ultralow-oxygen high-nitrogen corrosion-resistant cutting tool steel is prepared from the following chemical components in percentage by weight: 0.70 to 0.72 percent of C, 0.40 to 0.44 percent of Si, 0.48 to 0.52 percent of Mn, 13 to 14 percent of Cr, 0.08 to 0.12 percent of V, 0.105 to 0.115 percent of N, less than or equal to 0.0005 percent of O, less than or equal to 0.001 percent of S, less than or equal to 0.003 percent of P and the balance of Fe and inevitable impurity elements, and has the characteristics of high strength and high hardness and excellent processability.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to an ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel and a vacuum melting process thereof. Background Art

[0002] High nitrogen corrosion-resistant cutting tool steel is a kind of steel with excellent corrosion resistance, which is particularly suitable for manufacturing knives and other cutting tools, such as turning tools, milling cutters, drills, taps, dies, etc. These tools will be subjected to complex cutting forces during the cutting process, and strong friction will occur between the blade and the chips, resulting in an increase in the temperature of the blade, sometimes up to 500~600℃; therefore, cutting tool steel needs to have high hardness and wear resistance to ensure that it can still maintain cutting performance under high temperature and high pressure environment. In addition, during the cutting process, the tool must not only withstand pressure and friction, but also withstand bending, torsion, shear stress and impact and vibration loads; therefore, cutting tool steel needs to have certain strength, toughness and plasticity to prevent the tool from chipping or breaking due to impact and vibration.

[0003] It is known that adding an appropriate amount of nitrogen to steel can improve the tensile strength, hardness and wear resistance of cutting tool steel by forming nitrides with high strength and hardness, and the chromium nitride formed by the combination of nitrogen and chromium can effectively prevent oxygen or other corrosive media from further eroding the surface of cutting tool steel, forming a dense oxide film, thereby improving the corrosion resistance of cutting tool steel. In addition, nitrogen can also improve the high-temperature corrosion resistance of cutting tool steel, making it less prone to oxidation and corrosion in high-temperature environments, and can also improve the heat treatment hardening properties of cutting tool steel and improve the machinability of the material. The prior art clearly states that oxygen in steel will reduce the strength and hardness of cutting tool steel, making its corrosion resistance and processing properties worse, so the oxygen content in steel needs to be strictly controlled during steel smelting; currently, vacuum induction furnaces can be used to melt ultra-low oxygen content steel, but when melting nitrogen-containing steel, the nitrogen content is difficult to accurately control, so it is limited when preparing high-content nitrogen-containing steel. Summary of the invention

[0004] The present invention aims to provide an ultra-low oxygen, high nitrogen corrosion-resistant cutting tool steel and a vacuum melting process thereof, and adopts a vacuum induction furnace with a three-stage deoxidation and nitrogen control process, designs suitable raw material types, raw material formulas, raw material adding timing and adding methods, so as to obtain an ultra-low oxygen, high nitrogen corrosion-resistant cutting tool steel with an oxygen content lower than 0.0005% and a nitrogen content in the range of 0.105-0.115%.

[0005] To achieve the above object, the present invention proposes the following technical solutions: In the first aspect, an ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel is proposed, which includes the following chemical compositions by weight percentage: C 0.70-0.72%, Si 0.40-0.44%, Mn 0.48-0.52%, Cr 13-14%, V 0.08-0.12%, N0.105-0.115%, O≤0.0005%, S≤0.001%, P≤0.003%, and the balance is Fe and unavoidable impurity elements.

[0006] In the second aspect, a vacuum melting process for the ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel is proposed, comprising the following steps: Raw materials of industrial pure iron, ferrovanadium, polysilicon, metallic chromium and carbon particles accounting for 0.07-0.08% by weight of the total raw materials of vacuum melting cutting tool steel are loaded into the crucible of a vacuum induction furnace, and the air in the furnace is evacuated to reduce the pressure in the furnace to no more than 5 Pa; According to the process curve, power is supplied to the vacuum induction furnace, the raw materials in the crucible are melted under vacuum conditions, the power supply is adjusted, the raw material melting rate is controlled to be 1.5-2kg / min, the carbon-oxygen reaction is carried out, and the primary deoxidation is completed; After the raw materials are fully melted and the temperature of the molten steel is controlled to reach the first target temperature, carbon particles accounting for 0.04-0.05% by weight of the total raw materials of the vacuum-melted cutting tool steel are added to the molten steel to carry out a carbon-oxygen reaction to complete the second deoxidation; The pressure in the furnace is controlled to be no more than 5Pa for refining, the refining temperature is 1595-1605℃, the refining time is 13-15 minutes, and the third refining and deoxidation is completed; After filling the vacuum induction furnace with argon gas to make the pressure inside the furnace reach 0.096-0.098 MPa, adding metal manganese into the crucible for manganese alloying, and keeping the temperature for 5-8 minutes after melting; Adding ferrochromium nitride in batches into a crucible of a vacuum induction furnace for nitrogen alloying, and continuing to add all remaining carbon particles in batches into the crucible after melting to perform carbon alloying; After the carbon particles are fully melted, the temperature is kept for 6 to 7 minutes, the temperature of the molten steel is controlled to be 1595 to 1605° C., and the steel ingot is cast into a steel ingot. The steel ingot includes the following chemical components by weight percentage: C 0.70 to 0.72%, Si 0.40 to 0.44%, Mn 0.48 to 0.52%, Cr 13 to 14%, V 0.08 to 0.12%, N 0.105 to 0.115%, O≤0.0005%, S≤0.001%, P≤0.003%, and the balance is Fe and unavoidable impurity elements.

[0007] Furthermore, the weight percentage of each raw material added to the total raw materials of vacuum-melted cutting tool steel is: 0.18-0.19% ferrovanadium, 0.42-0.43% polysilicon, 13.5-13.6% metallic chromium, 0.51-0.52% metallic manganese, 2.9-3% ferrochrome nitride, 0.72-0.73% carbon particles, and the remainder is industrial pure iron.

[0008] Furthermore, the first target temperature is 1595-1605°C.

[0009] Furthermore, the raw materials industrial pure iron, ferrovanadium, polycrystalline silicon, metallic chromium and carbon particles are placed in the crucible in the order of metallic chromium, polycrystalline silicon, ferrovanadium and industrial pure iron from bottom to top, and the carbon particles are scattered between polycrystalline silicon and ferrovanadium.

[0010] Furthermore, the main element contents of the raw materials, namely, industrial pure iron, carbon particles, polysilicon, metallic manganese, and metallic chromium, are all greater than 99.9%, and the oxygen element contents are all less than 0.0020%.

[0011] Furthermore, the raw material nitrided chromium iron has a nitrogen content of 6.8%, a chromium content of 57.6%, and the remainder is iron and unavoidable impurity elements.

[0012] Furthermore, the vanadium content in the raw material ferrovanadium is 53.8%, and the remainder is iron and inevitable impurity elements.

[0013] Furthermore, the raw material ferrochromium nitride is in granular form, and its particle size is D, 5 mm≤D≤10 mm.

[0014] Furthermore, ferrochromium nitride is added into the crucible of the vacuum induction furnace in 3 to 5 batches for nitrogen alloying, and after melting, all remaining carbon particles are continuously added into the crucible in 6 to 9 batches for carbon alloying.

[0015] It can be seen from the above technical solutions that the technical solutions of the present invention have the following beneficial effects: The ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel and vacuum melting process thereof disclosed in the present invention are intended to solve the problem that the nitrogen content of the corrosion-resistant cutting tool steel produced by vacuum induction melting has large fluctuation and cannot be precisely controlled. The process adopts a vacuum induction furnace for smelting, and the weight percentages are selected as follows: 0.18-0.19% ferrovanadium, 0.42-0.43% polysilicon, 13.5-13.6% metallic chromium, 0.51-0.52% metallic manganese, 2.9-3% ferrochrome nitride, 0.72-0.73% carbon particles, and the balance is industrial pure iron as raw materials. The timing and method of adding the raw materials are set, and the ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel is produced through a three-step deoxidation process in combination with a nitrogen control process. The ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel finally obtained includes the following chemical components by weight percentage: 0.70-0.72% C, 0.40-0.44% Si, 0.48-0.52% Mn, 13-14% Cr, and 13-14% V. 0.08~0.12%, N 0.105~0.115%, O≤0.0005%, S≤0.001%, P≤0.003%, the remainder is Fe and inevitable impurity elements. The vacuum melting process of the present invention, on the one hand, selects and proportions raw materials, and controls the oxygen content in the molten steel by adding carbon particles and refining to achieve three deoxidation. On the other hand, through raw material selection and proportioning, under oxygen control conditions, further adjusts the reaction environment, molten steel temperature and the order of alloy addition to achieve precise control of the nitrogen content in the molten steel; finally, the ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel of the above formula is obtained.

[0016] The ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel produced by the present invention has an extension strength Rp (0.2) of 421 MPa, a tensile strength Rm of 693 MPa, an elongation of 30.7%, and a hardness HRB of 56. Therefore, it not only has the characteristics of high strength and high hardness, but also has excellent processing performance. In addition, the pitting potential of the ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel of the present invention reaches 0.109 V, which is significantly improved compared with the existing conventional steel grades for processing cutting tools.

[0017] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered to be part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

[0018] The foregoing and other aspects and features of the present invention can be more fully understood from the following description in conjunction with the embodiments. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned from the practice of the specific embodiments according to the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme of the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described 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. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with general skills in the field to which the present invention belongs.

[0020] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular form of "a", "an" or "the" and other similar words do not indicate a quantitative limitation, but indicate the existence of at least one. "Include" or "comprises" and other similar words mean that the elements or objects appearing before "include" or "comprises" include the features, wholes, steps, operations, elements and / or components listed after "include" or "comprises", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections.

[0021] Based on the drawbacks of high oxygen content in cutting tool steel, technicians have found that ultra-low oxygen content steel can be melted in a vacuum induction furnace; at the same time, the study found that adding an appropriate amount of nitrogen to the formula of cutting tool steel can improve the machinability, tensile strength, hardness, wear resistance and corrosion resistance of cutting tool steel by forming nitrides with high strength and hardness; but when the vacuum induction furnace is used to smelt molten steel, it is difficult to accurately control the nitrogen content, and its application in the preparation of low-oxygen and high-nitrogen steel is limited. Therefore, the present invention aims to propose an ultra-low oxygen and high-nitrogen corrosion-resistant cutting tool steel and its vacuum melting process, so as to achieve accurate control of the oxygen and nitrogen content in the molten steel using a vacuum induction furnace.

[0022] Specifically, a vacuum melting process for ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel is provided, wherein the raw materials shown in Table 1 are used to prepare the ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel by vacuum melting; the ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel comprises the following chemical components by weight percentage: C 0.70-0.72%, Si 0.40-0.44%, Mn 0.48-0.52%, Cr 13-14%, V 0.08-0.12%, N 0.105-0.115%, O≤0.0005%, S≤0.001%, P≤0.003%, and the balance is Fe and unavoidable impurity elements; Table 1 Raw material composition for preparing ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel

[0023] Among the above raw materials, the main element contents of raw materials industrial pure iron, carbon particles, polysilicon, metallic manganese and metallic chromium are all greater than 99.9%, and the oxygen content is all less than 0.0020%; the nitrogen content of raw material ferrochrome nitride is 6.8%, the chromium content is 57.6%, and the balance is iron and inevitable impurity elements, and the ferrochrome nitride is in granular form with a particle size of D, 5 mm≤D≤10 mm; the vanadium content of raw material ferrovanadium alloy is 53.8%, and the balance is iron and inevitable impurity elements; The specific process of vacuum melting includes the following steps: Raw materials of industrial pure iron, ferrovanadium, polycrystalline silicon, metallic chromium and carbon particles accounting for 0.07-0.08% by weight of the total raw materials of vacuum melting cutting tool steel are loaded into the crucible of a vacuum induction furnace, and the air in the furnace is evacuated to reduce the pressure in the furnace to no more than 5 Pa; the raw materials are placed in the crucible in the order of metallic chromium, polycrystalline silicon, ferrovanadium, and industrial pure iron from bottom to top, and the carbon particles are scattered between polycrystalline silicon and ferrovanadium; According to the process curve, power is supplied to the vacuum induction furnace, the raw materials in the crucible are melted under vacuum conditions, the power supply is adjusted, the raw material melting rate is controlled to be 1.5-2kg / min, the carbon-oxygen reaction is carried out, and the primary deoxidation is completed; After the raw materials are fully melted, the temperature of the molten steel is controlled to reach the first target temperature of 1595-1605°C, and carbon particles accounting for 0.04-0.05% by weight of the total raw materials of the vacuum-melted cutting tool steel are added to the molten steel to carry out a carbon-oxygen reaction to complete the second deoxidation; The pressure in the furnace is controlled to be no more than 5Pa for refining, the refining temperature is 1595-1605℃, the refining time is 13-15 minutes, and the third refining and deoxidation is completed; After filling the vacuum induction furnace with argon gas to make the pressure inside the furnace reach 0.096-0.098 MPa, adding metal manganese into the crucible for manganese alloying, and keeping the temperature for 5-8 minutes after melting; Adding ferrochromium nitride into the crucible of the vacuum induction furnace in 3 to 5 batches for nitrogen alloying, and adding all the remaining carbon particles into the crucible in 6 to 9 batches after melting to perform carbon alloying; After the carbon particles are fully melted, the temperature is kept for 6 to 7 minutes, the temperature of the molten steel is controlled to be 1595 to 1605° C., and the steel ingot is cast into a steel ingot. The steel ingot includes the following chemical components by weight percentage: C 0.70 to 0.72%, Si 0.40 to 0.44%, Mn 0.48 to 0.52%, Cr 13 to 14%, V 0.08 to 0.12%, N 0.105 to 0.115%, O≤0.0005%, S≤0.001%, P≤0.003%, and the balance is Fe and unavoidable impurity elements.

[0024] The present invention first obtains the above-mentioned ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel, and secondly, during vacuum melting, firstly, raw material selection is used as the basis for the subsequent preparation of each target component content, and then, in the vacuum-like environment provided by the vacuum induction furnace, the order of adding raw materials, adding carbon particles and refining are controlled to achieve three deoxidation of the molten steel to control the oxygen content in the molten steel, and then the atmosphere in the vacuum induction furnace is adjusted to an argon environment under oxygen control conditions, and further, the temperature of the molten steel and the order of adding alloys are controlled to achieve precise control of the nitrogen content in the molten steel. The present invention realizes precise nitrogen control in the vacuum melting method by designing the raw material ratio and controlling oxygen, and then controlling the reaction environment, reaction temperature and nitrogen control steps, thereby solving the technical problem that the existing vacuum induction furnace cannot accurately control the nitrogen content when melting ultra-low oxygen steel, and is thus limited in the preparation of high nitrogen steel.

[0025] The vacuum melting process of the ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel disclosed in the present invention will be further specifically introduced below in conjunction with specific embodiments.

[0026] Example 1 The chemical composition requirements of the ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel to be prepared in this embodiment are shown in Table 2 below, and Table 2 shows the upper and lower limits of the content of each chemical element in the cutting tool steel; Table 2 Chemical composition requirements of ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel (wt.%)

[0027] Example The raw material formula for preparing the ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel with the above chemical composition is shown in Table 3 below.

[0028] Table 3 Raw material ratios for preparing ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel

[0029] The specific steps of vacuum melting for preparing the target cutting tool steel are as follows: (1) Loading: All industrial pure iron, ferrovanadium, polycrystalline silicon, metallic chromium and carbon particles accounting for 0.07% of the total weight percentage of the raw materials of vacuum melting cutting tool steel are loaded into the crucible. The order of placement from bottom to top is metallic chromium, polycrystalline silicon, ferrovanadium, industrial pure iron, and carbon particles are scattered between polycrystalline silicon and ferrovanadium; (2) Vacuuming: evacuate the air in the furnace so that the pressure in the vacuum induction furnace does not exceed 5 Pa; (3) Power on to melt the initial charge: Power the vacuum induction furnace according to the process curve, melt the initial charge under vacuum conditions, adjust the power supply, and control the melting rate to 2 kg / min to ensure that the carbon-oxygen reaction is fully completed and the initial deoxidation is completed; (4) Temperature measurement: control the temperature of molten steel to 1600°C; (5) Second deoxidation: adding carbon particles in an amount of 0.05% by weight of the total raw material of the vacuum-melted cutting tool steel to the above-mentioned molten steel to complete the second deoxidation; (6) Refining: Keep all vacuum pumps turned on, control the pressure in the furnace to not exceed 5 Pa, perform refining at a refining temperature of 1600 °C, and a refining time of 14 min to complete the third refining and deoxidation; (7) Argon filling: Turn off all vacuum pumps and fill the vacuum induction furnace with argon until the pressure inside the furnace reaches 0.098 MPa; (8) Manganese alloying: Add all the manganese metal into the crucible of the vacuum induction furnace, melt it and keep it warm for 7 minutes; elemental manganese is beneficial to the retention of nitrogen in the molten steel, that is, it has a nitrogen fixing effect, but it is easy to volatilize, so it is added to the molten steel after the reaction environment is adjusted to an argon environment; (9) Nitrogen alloying: Add all the ferrochromium nitride into the crucible of the vacuum induction furnace in 4 batches, and add the next batch after each batch is completely melted. During the dissolution process, the ferrochromium nitride will discharge nitrogen molecules in the melt, resulting in the loss of nitrogen. However, the probability of nitrogen loss can be reduced in an argon environment, thereby increasing the nitrogen recovery rate. (10) Carbon alloying: Add all the remaining carbon particles into the crucible in 8 batches, and add the next batch after each batch is melted; (11) Composition analysis: After the carbon particles are completely melted, keep them warm for 7 min, take samples and analyze the chemical composition. The specific composition is shown in Table 4 below; Table 4 Melting composition of ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel / wt.%

[0030] (12) Temperature measurement and pouring: The composition of the molten steel meets the target requirements and is ready for pouring. Before pouring, the temperature of the molten steel is measured to ensure that the temperature of the molten steel is at 1600°C and then poured into steel ingots.

[0031] The above-mentioned steel ingot and 2Cr13 steel were used to carry out performance comparison experiments. Samples were taken from hot-rolled plates to prepare φ12mm tensile specimens, standard V-notch Charpy impact specimens (size 10mm×10mm×55mm) and corrosion specimens (size 50mm×25mm×3mm). 2Cr13 steel is a commonly used steel for preparing cutting tools. Then, each specimen was quenched and tempered, where the quenching temperature was 1050℃, kept warm for 20min, water-cooled, and the tempering temperature was 520℃, kept warm for 60min, and air-cooled. Then, the performance of each specimen was tested in turn. In addition, the pitting potential of the two steels was measured under the conditions of 25℃ and 3.5% NaCl solution. The specific performance data are shown in Table 5 below: Table 5 Performance comparison between the steel obtained in the embodiment and 2Cr13 steel

[0032] As shown in Table 5, the extension strength, tensile strength, hardness, elongation and impact energy value of the ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel prepared by the present invention are significantly higher than those of the comparison steel type 2Cr13, and the processing performance is better than that of the comparison steel type; in terms of pitting potential, the ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel prepared by the present invention has a higher pitting potential, which indicates that the ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel of the present invention has better anti-pitting performance and good corrosion resistance.

[0033] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. An ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel, characterized in that: Calculated by weight percentage, it includes the following chemical components: C 0.70-0.72%, Si 0.40-0.44%, Mn 0.48-0.52%, Cr 13-14%, V 0.08-0.12%, N 0.105-0.115%, O≤0.0005%, S≤0.001%, P≤0.003%, and the balance is Fe and unavoidable impurity elements.

2. A vacuum melting process for ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel, characterized in that: The steps include: Raw materials of industrial pure iron, ferrovanadium, polysilicon, metallic chromium and carbon particles accounting for 0.07-0.08% by weight of the total raw materials of vacuum melting cutting tool steel are loaded into the crucible of a vacuum induction furnace, and the air in the furnace is evacuated to reduce the pressure in the furnace to no more than 5 Pa; According to the process curve, power is supplied to the vacuum induction furnace, the raw materials in the crucible are melted under vacuum conditions, the power supply is adjusted, the raw material melting rate is controlled to be 1.5-2kg / min, the carbon-oxygen reaction is carried out, and the primary deoxidation is completed; After the raw materials are fully melted and the temperature of the molten steel is controlled to reach the first target temperature, carbon particles accounting for 0.04-0.05% by weight of the total raw materials of the vacuum-melted cutting tool steel are added to the molten steel to carry out a carbon-oxygen reaction to complete the second deoxidation; The pressure in the furnace is controlled to be no more than 5Pa for refining, the refining temperature is 1595-1605℃, the refining time is 13-15 minutes, and the third refining and deoxidation is completed; After filling the vacuum induction furnace with argon gas to make the pressure inside the furnace reach 0.096-0.098 MPa, add metal manganese into the crucible for manganese alloying, and keep the temperature for 5-8 minutes after melting; Adding ferrochromium nitride in batches into a crucible of a vacuum induction furnace for nitrogen alloying, and continuing to add all remaining carbon particles in batches into the crucible after melting to perform carbon alloying; After the carbon particles are fully melted, the temperature is kept for 6 to 7 minutes, the temperature of the molten steel is controlled to be 1595 to 1605° C., and the steel ingot is cast into a steel ingot. The steel ingot includes the following chemical components by weight percentage: C 0.70 to 0.72%, Si 0.40 to 0.44%, Mn 0.48 to 0.52%, Cr13 to 14%, V 0.08 to 0.12%, N 0.105 to 0.115%, O≤0.0005%, S≤0.001%, P≤0.003%, and the balance is Fe and unavoidable impurity elements.

3. The vacuum melting process of ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel according to claim 2, characterized in that: The weight percentage of each raw material added to the total raw materials of vacuum-melted cutting tool steel is: 0.18-0.19% of ferrovanadium, 0.42-0.43% of polysilicon, 13.5-13.6% of metallic chromium, 0.51-0.52% of metallic manganese, 2.9-3% of ferrochrome nitride, 0.72-0.73% of carbon particles, and the balance is industrial pure iron.

4. The vacuum melting process of ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel according to claim 2, characterized in that: The first target temperature is 1595-1605°C.

5. The vacuum melting process of ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel according to claim 2, characterized in that: The raw materials industrial pure iron, ferrovanadium, polycrystalline silicon, metal chromium and carbon particles are placed in the crucible in the order of metal chromium, polycrystalline silicon, ferrovanadium and industrial pure iron from bottom to top, and the carbon particles are scattered between polycrystalline silicon and ferrovanadium.

6. The vacuum melting process of ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel according to claim 2, characterized in that: The main element contents of the raw materials, industrial pure iron, carbon particles, polysilicon, metallic manganese and metallic chromium, are all greater than 99.9%, and the oxygen element content is all less than 0.0020%.

7. The vacuum melting process of ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel according to claim 2, characterized in that: The raw material nitrided chromium iron has a nitrogen content of 6.8%, a chromium content of 57.6%, and the remainder is iron and unavoidable impurity elements.

8. The vacuum melting process of ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel according to claim 2, characterized in that: The vanadium content of the raw material ferrovanadium is 53.8%, and the remainder is iron and inevitable impurity elements.

9. The vacuum melting process of ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel according to claim 2, characterized in that: The raw material ferrochromium nitride is in granular form, and its particle size is D, 5 mm≤D≤10 mm.

10. The vacuum melting process of ultra-low oxygen and high nitrogen corrosion-resistant cutting tool steel according to claim 2, characterized in that: The ferrochromium nitride is added into the crucible of the vacuum induction furnace in 3 to 5 batches for nitrogen alloying, and after melting, all the remaining carbon particles are continuously added into the crucible in 6 to 9 batches for carbon alloying.

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