A high-strength and high-wear-resistant alloy tool steel and its smelting method

Abstract

The present invention belongs to the technical field of steel smelting, and specifically relates to a high-strength and high-wear-resistant alloy tool steel and its smelting method. The chemical composition of the steel, calculated by weight percentage, has the following elemental composition: [C] 0.70% - 0.76%, [Si] 1.40% - 1.60%, [Mn] 0.50% - 0.80%, [Cr] 1.00% - 1.20%, [Ni] 0.20% - 0.26%, [V] 0.14% - 0.20%, [Al] 0.020% - 0.040%, [P] ≤ 0.025%, [S] ≤ 0.020%, and the balance is Fe and inevitable impurities. The smelting method includes converter smelting, LF refining, RH vacuum treatment, and bloom continuous casting. Aiming at the final use of this material, the present invention optimizes the design from two aspects: composition and smelting process, and the steel produced has stable composition, uniform macrostructure, and high cleanliness.

Description

Technical Field

[0001] The present invention belongs to the technical field of steel smelting, and specifically relates to a high-strength and high-wear-resistant alloy tool steel and a smelting method thereof. Background Art

[0002] Alloy tool steel has better hardenability, toughness, wear resistance and heat resistance compared with carbon tool steel. Therefore, under more severe service conditions, it has a higher service life. Electric wood chisels are a type of product with extremely high requirements in alloy tool steel. The finished products need to have properties such as high strength, high wear resistance, torsion resistance, and explosion resistance. Currently, when processed with 9SiCr material, it is found through testing that the wear resistance of the product does not meet the requirements, and fracture problems occur during use; when processed with 67SiCrNiMoV material, it is found through testing that the wear resistance and torsion resistance of the product also do not meet the requirements; when processed with 60Si2CrV material, it is found through testing that the strength of the product does not meet the requirements. Therefore, for this product, the composition needs to be reasonably designed according to the end use to meet the requirements of high strength and high wear resistance during use.

[0003] During the fatigue test of the product, non-metallic inclusions in the steel destroy the continuity of the matrix and often become the fatigue source of fracture during composition testing. Especially, the influence of large-sized inclusions is more obvious. Therefore, the control of non-metallic inclusions during the smelting process is extremely crucial. In addition, the uniformity of the cross-sectional structure of the steel wire rod directly affects the downstream processing technology and the final performance of the product. For example, central shrinkage and central segregation in the steel billet are likely to form hard and brittle martensite structures, resulting in problems such as brittle fracture during transportation or increased downstream spheroidizing costs. Therefore, for the alloy tool steel used to process electric wood chisels, reasonable design needs to be carried out from both the composition and the process aspects to meet the requirements of high strength and high wear resistance of the product. Summary of the Invention

[0004] Aiming at the problems of insufficient strength, low wear resistance, and failure to meet requirements such as torsion resistance and explosion resistance during the testing process of the existing alloy tool steel for high-strength and high-wear-resistant wood chisels, the present invention provides a high-strength and high-wear-resistant alloy tool steel and a smelting method thereof through composition design, process flow, and control of key parameters, which can ensure stable steel composition, uniform macrostructure, high cleanliness, and the processed products meet the requirements of high strength and high wear resistance.

[0005] To achieve the above object, the composition of the high-strength and high-wear-resistant alloy tool steel of the present invention is by weight percentage: [C] 0.70% - 0.76%, [Si] 1.40% - 1.60%, [Mn] 0.50% - 0.80%, [Cr] 1.00% - 1.20%, [Ni] 0.20% - 0.26%, [V] 0.14% - 0.20%, [Al] 0.020% - 0.040%, [P] ≤ 0.025%, [S] ≤ 0.020%, and the balance is Fe and unavoidable impurities.

[0006] Preferably, its chemical composition is by weight percentage: [C] 0.72% - 0.74%, [Si] 1.52% - 1.58%, [Mn] 0.52% - 0.58%, [Cr] 1.05% - 1.10%, [Ni] 0.21% - 0.24%, [V] 0.16% - 0.18%, [Al] 0.025% - 0.035%, [P] ≤ 0.015%, [S] ≤ 0.010%, and the balance is Fe and unavoidable impurities.

[0007] The material prepared by the present invention is used for processing electric wood chisels, and this product has extremely strict requirements for the strength, wear resistance, torsional resistance, toughness, etc. of the final product. Under the condition of stable heat treatment performance, the key factor affecting the final performance of the product is the design of the chemical composition. And for the design of a certain property of the composition, in addition to being mainly affected by a certain element, it is also affected by multiple elements at the same time. Therefore, for example, the strength of the product is affected by C, Si, Mn, and Ni at the same time. As the element with the greatest influence on strength, when C is designed low, the hardness cannot meet the requirements, and when it is designed high, the brittleness increases and the toughness decreases. Therefore, according to the test results of similar products, the final range is optimized; Si has a great influence on improving the elastic limit and torsional property. If the composition is designed low, there will be a problem of torsional fracture. If the composition is designed high, the decarburization tendency will increase during the production and heat treatment processes. At the same time, combined with other elements, it has a beneficial effect on corrosion resistance, heat resistance, etc. Therefore, according to the test results of similar products, the final range is optimized; Cr and V elements mainly affect wear resistance and toughness respectively, and at the same time affect the strength of the steel. Therefore, according to the use of the product, a rational design of multiple elements needs to be considered. The reasons for the composition design of the present invention are as follows:

[0008] [C] is a key element affecting the strength, hardness, toughness, hardenability, and wear resistance of steel. When the carbon content is low, the hardness of the steel is low and the wear resistance is poor. In the present invention, it is preferably 0.72% - 0.74%.

[0009] [Si] can significantly improve the elastic limit, yield point and strength of steel. Adding a certain amount of silicon to quenched and tempered steel, when combined with chromium, molybdenum, etc., can improve properties such as oxidation resistance, corrosion resistance and heat resistance. In addition, silicon is also a commonly used deoxidizer, partially replacing aluminum for deoxidation. In the present invention, it is preferably 1.52% - 1.58%.

[0010] [Mn] can increase the strength of steel, weaken and eliminate the adverse effects of sulfur, and can significantly improve the hardenability of steel, improving the hot working performance of steel. In the present invention, it is preferably 0.52 - 0.58%.

[0011] [Cr] is one of the basic elements of wear-resistant materials, significantly increasing strength, hardness and wear resistance, and can also improve the oxidation resistance and corrosion resistance of steel. In the present invention, it is preferably 1.05% - 1.10%.

[0012] [Ni] can increase the strength of steel while maintaining good plasticity and toughness, and has rust prevention and heat resistance at high temperatures. However, nickel is a relatively scarce resource. In the present invention, it is preferably 0.21% - 0.24%.

[0013] [V] can refine the grain size of the structure, increase strength and toughness, form carbides with carbon, and can improve the hydrogen corrosion resistance under high temperature and high pressure. In the present invention, it is preferably 0.16% - 0.18%.

[0014] [Al], as a key element for deoxidation, can simultaneously refine the grains and improve the impact toughness. Aluminum also has oxidation resistance and corrosion resistance. When combined with chromium and silicon, it can significantly improve the high-temperature scale resistance and high-temperature corrosion resistance of steel. However, too high a content will affect the hot working performance and welding performance of steel. In the present invention, it is preferably 0.025% - 0.035%.

[0015] [P] and [S] are generally harmful elements in steel. In the present invention, it is preferably [P] ≤ 0.015% and [S] ≤ 0.010%.

[0016] For the high-strength and high-wear-resistant alloy tool steel, the present invention also provides its smelting process, including converter smelting, LF refining, RH vacuum treatment, and bloom continuous casting. The specific operations are as follows:

[0017] (1) Converter smelting

[0018] The converter is charged with 110 - 130 tons of hot metal and 10 - 30 tons of scrap. The requirements for hot metal are as follows: [Si]: 0.50% - 0.80%, [P] ≤ 0.10%, [S] ≤ 0.030%, temperature 1300 - 1400°C. High - carbon - tapping operation is adopted at the end of smelting. The [C] content in the tapped steel is ≥ 0.05%, the [P] content in the tapped steel is ≤ 0.015%, the tapping temperature is greater than 1620 - 1650°C, the tapping time is 4 - 6 minutes. Starting from 30 seconds after tapping, deoxidizer, alloy, carburizer and slag materials are added respectively. Double - blocking operation is adopted after tapping, that is, a slide gate and a slag - blocking cone are used simultaneously for slag - blocking. After tapping, the molten steel is lifted to LF for refining.

[0019] Among them, the deoxidizer added during tapping is Al blocks, the alloys are ferrosilicon, high - carbon ferromanganese, high - carbon ferrochrome, ferrovanadium, nickel plates, and the slag materials for tapping are lime and slag - melting agents, with the addition amounts of 500 kg / furnace and 300 kg / furnace respectively.

[0020] (2) LF refining

[0021] Samples are taken before the molten steel enters LF for refining. In the early stage of refining, Al pellets and silicon carbide are used for deoxidation and desulfurization. In the middle and late stages, silicon carbide is used to maintain the slag, that is, a small amount of silicon carbide is evenly added on the slag surface to ensure a reducing atmosphere on the slag surface. In the middle stage, other alloy components are adjusted to the target values according to the LF incoming sample, and the temperature is adjusted to the appropriate level. The whole process of refining adopts small - argon - stirring smelting, that is, the argon - stirring intensity is 50 - 100 L / min.

[0022] (3) RH vacuum treatment

[0023] After the molten steel reaches the RH station, the ladle is lifted to the vacuum chamber, and the circulation vacuum pumping starts. Argon is used as the lifting gas, and the lifting gas is controlled at 80 - 100 Nm 3 / h. After the vacuum degree is less than 120 Pa, the pressure is maintained for 15 minutes and then the pressure is released. A molten - steel sample is taken. According to the analysis results of the sample, the Al content is adjusted by feeding aluminum wire, and then 50 - 100 meters of calcium wire is fed for modification treatment. After soft blowing for 15 - 20 minutes, the molten steel is lifted to the continuous casting for casting.

[0024] (4) Bloom continuous casting

[0025] Before the continuous casting starts, the tundish is baked to ensure that the ladle temperature for the first casting heat is 1525 - 1545 °C, and for the continuous casting heats is 1500 - 1525 °C. After the tundish stops baking, argon is purged inside for 3 - 5 minutes. During casting, protective casting is carried out throughout the surface of the molten steel level in the tundish. The tundish uses an integral nozzle for casting, and the casting superheat is controlled at 20 - 30 °C. After each heat of casting, slag and steel are left in the ladle. When changing the ladle at the end of each heat of casting, the minimum liquid level height in the tundish is above 600 mm. The continuous casting speed is controlled at 0.80 m / min, the temperature difference of the return water of the first cooling water is controlled at 4 - 6 °C, the specific water volume of the secondary cooling is 0.20 L / kg. The mold and the final electromagnetic stirring are started, and soft reduction is adopted at the solidification end. The bloom billet is slowly cooled in the pit, and the temperature when entering the pit is greater than 500 °C. It can only be taken out of the pit after the heat preservation time is greater than 42 hours.

[0026] Among them, for the protective casting, it is required that the first layer in contact with the molten steel in the tundish uses an alkaline covering agent, and the second layer uses carbonized rice husk ash, and there is no molten steel exposed on the surface of the tundish; after each heat of casting, slag and steel are left in the ladle, that is, 3 - 5 tons of slag and steel are left in the ladle after each heat of casting; the cross-section of the continuous casting bloom billet is 300 mm × 325 mm, and the 1# - 4# rolls are used for reduction at the solidification end, and the reduction amounts are 2 mm, 3 mm, 3 mm, and 4 mm respectively, and the total reduction amount is 12 mm.

[0027] Starting from the final requirements of the product, the composition of the alloy tool steel is designed in the present invention. At the same time, the smelting process is determined as converter - LF refining - RH vacuum treatment - bloom continuous casting. Strict requirements are imposed on the hot metal for the converter to achieve low consumption of auxiliary materials and efficient smelting during the converter smelting process. High - carbon tapping is carried out during tapping, and at the same time, double - ladle tapping is coordinated to prevent the increase in the amount of deoxidizer due to over - oxidation of the molten steel and the increase in the operation difficulty for LF refining; during the LF refining process, rapid deoxidation is adopted in the early stage and slag - protecting operation is carried out in the middle and later stages. At the same time, small - argon stirring is adopted throughout the refining process to prevent the generation of large - sized inclusions caused by slag entrainment during the smelting process; through low vacuum degree and pressure - holding time, RH effectively removes non - metallic inclusions and obtains high - cleanliness molten steel; before the continuous casting starts, oxygen in the steel is removed by argon blowing. When changing the ladle at the end of each heat of casting, the height of the molten steel level in the tundish is controlled to prevent slag entrainment problems caused by oxidation during starting and the impact of the next heat of casting when the molten steel level in the tundish is relatively low; integral nozzle casting is adopted, and protective casting is carried out throughout the casting process, combined with leaving slag and steel after the ladle casting is completed, effectively avoiding secondary oxidation of the molten steel. The cross - section of the continuous casting bloom billet in the present invention is preferably 300 mm × 325 mm, and the mold and the final electromagnetic stirring are adopted. Combining the casting speed, secondary cooling parameters and the solid - phase ratio of the steel grade at the straightening machine position, the soft reduction process is adopted to effectively control the internal quality of the slab, thereby improving the cross - section structure of the rolled material. After rolling, the steel billet after smelting meets the requirements for the user to process it into a high - strength and high - wear - resistance alloy tool steel. Detailed implementation mode

[0028] The present invention will be further described in detail below in combination with the production examples of high-strength and high-wear-resistant alloy tool steel. The conditions not specified are conventional conditions:

[0029] Example 1

[0030] (1) Converter smelting

[0031] The converter is charged according to the weight ratio of 110 tons of hot metal and 28 tons of scrap steel. The hot metal has [Si] 0.65%, [P] 0.060%, [S] 0.022%, the temperature is 1348 °C, the tapping [C] at the end of smelting is 0.11%, the tapping [P] is 0.011%, the tapping temperature is 1629 °C, the tapping time is 5 min, and 130 kg of aluminum blocks are added respectively 30 s after tapping. After adding the aluminum blocks, 2705 kg of ferrosilicon, 700 kg of high-carbon ferromanganese, 2700 kg of high-carbon ferrochrome, 350 kg of ferrovanadium, 330 kg of nickel plates are added, then 600 kg of carburizer is added, and finally 500 kg of lime and 300 kg of slag-making agent are added. The tapping is blocked by a slide plate and a slag stopper at the end of tapping. After the tapping is completed, the molten steel is lifted to LF for refining.

[0032] (2) LF refining

[0033] Samples are taken before the LF refining station enters. 50 kg of Al grains and 80 kg of silicon carbide are used for deoxidation and desulfurization when entering the refining station. After smelting for 15 min, silicon carbide is used to maintain the slag, that is, a small amount of silicon carbide is added evenly on the slag surface to ensure that the slag surface is in a reducing atmosphere. According to the analysis results of the incoming sample, 50 kg of ferrosilicon, 120 kg of high-carbon ferromanganese, 200 kg of high-carbon ferrochrome, 50 kg of ferrovanadium, 30 kg of nickel plates are added respectively, and the temperature is adjusted to 1585 °C. The argon stirring intensity throughout the refining process is 70 L / min.

[0034] (3) RH vacuum treatment

[0035] After the molten steel reaches the RH station, the ladle is lifted to the vacuum tank, and the cyclic vacuum pumping starts. The lifting gas is controlled at 90 Nm 3 / h. After the vacuum degree reaches 70 Pa, it is kept under pressure for 15 min and then the pressure is released. 100 m of calcium wire is fed for modification treatment. After soft blowing for 20 min, the molten steel is lifted to the continuous casting for casting.

[0036] (4) Bloom continuous casting

[0037] Before the continuous casting starts, the tundish is baked at a temperature of 1180 °C. After the tundish stops baking, argon is filled into it for 4 minutes. When the ladle starts pouring, 80% of the rated weight of the tundish molten steel is placed, and then 200 kg of basic covering agent is added. After that, 50 kg of carbonized rice husk ash is added. The tundish is cast using an integral nozzle, and the superheat of the first ladle during pouring is 30 °C. When changing the ladle after the ladle casting is completed, the height of the tundish liquid level is 700 mm. The continuous casting drawing speed is controlled at 0.80 m / min, the temperature difference of the return water in the first cooling water is controlled between 4 and 6 °C, the specific water consumption of the secondary cooling is 0.20 L / kg. The mold and the end electromagnetic stirring are started, and the stirring parameters are 200 A / 2 Hz and 300 A / 6 Hz respectively. Light reduction is adopted at the solidification end, and the 1# to 4# rolls are used for reduction, and the reduction amounts are 2 mm, 3 mm, 3 mm, and 4 mm respectively. After the ladle casting is completed, 4 tons of slag is left in the ladle. The bloom is slowly cooled in a pit. The temperature when entering the pit is 550 °C, and it is taken out of the pit after 48 hours of heat preservation time.

[0038] Example 2

[0039] In step (1), the converter is charged with 118 tons of hot metal and 24 tons of scrap steel in a weight ratio. The hot metal has [Si] 0.70%, [P] 0.050%, [S] 0.020%, and the temperature is 1365 °C. At the end of smelting, the tapped steel has [C] 0.09%, [P] 0.013%, and the tapping temperature is 1635 °C.

[0040] In step (2), according to the analysis results of the incoming sample, 70 kg of ferrosilicon, 150 kg of high-carbon ferromanganese, 180 kg of high-carbon ferrochromium, 40 kg of ferrovanadium, and 25 kg of nickel plate are added respectively, and the temperature is adjusted to 1569 °C.

[0041] In step (3), 80 m of calcium wire is fed for modification treatment.

[0042] In step (4), it is a continuous casting heat. During the tundish casting process, the molten steel is not exposed, and the superheat during casting is 23 °C.

[0043] The rest is the same as in Example 1.

[0044] Example 3

[0045] In step (1), the converter is charged with 125 tons of hot metal and 20 tons of scrap steel in a weight ratio. The hot metal has [Si] 0.67%, [P] 0.040%, [S] 0.019%, and the temperature is 1370 °C. At the end of smelting, the tapped steel has [C] 0.12%, [P] 0.009%, and the tapping temperature is 1640 °C.

[0046] In step (2), according to the analysis results of the incoming sample, 45 kg of ferrosilicon, 130 kg of high-carbon ferromanganese, 220 kg of high-carbon ferrochromium, 55 kg of ferrovanadium, and 35 kg of nickel plate are added respectively, and the temperature is adjusted to 1565 °C.

[0047] In step (3), 60 m of calcium wire is fed in for denaturation treatment.

[0048] In step (4), it is a continuous casting heat. During the tundish casting process, the molten steel is not exposed, and the casting superheat is 25 °C.

[0049] The rest is the same as in Example 1.

[0050] Comparative Example 1

[0051] Compared with Example 1, in Comparative Example 1, in the converter smelting of step 1, "add another 600 kg of carburizer" is adjusted to "add another 500 kg of carburizer", and other operations of converter smelting, LF refining, RH vacuum treatment and bloom continuous casting are the same as in Example 1.

[0052] Comparative Example 2

[0053] Compared with Example 1, in Comparative Example 2, in the converter smelting of step 1, "after adding the aluminum blocks, add 2705 kg of ferrosilicon, 700 kg of high-carbon ferromanganese, 2700 kg of high-carbon ferrochrome, 350 kg of ferrovanadium, 330 kg of nickel plate" is adjusted to "after adding the aluminum blocks, add 1860 kg of ferrosilicon, 700 kg of high-carbon ferromanganese, 2700 kg of high-carbon ferrochrome, 350 kg of ferrovanadium, 330 kg of nickel plate", and other operations of converter smelting, LF refining, RH vacuum treatment and bloom continuous casting are the same as in Example 1.

[0054] Comparative Example 3

[0055] Compared with Example 1, in Comparative Example 3, in the bloom continuous casting of step 4, "when changing the ladle at the end of ladle casting, the height of the tundish liquid level is 700 mm" is adjusted to "when changing the ladle at the end of ladle casting, the height of the tundish liquid level is 400 mm", and other operations of converter smelting, LF refining, RH vacuum treatment and bloom continuous casting are the same as in Example 1.

[0056] Comparative Example 4

[0057] Compared with Example 1, in Comparative Example 4, in the bloom continuous casting of step 4, "the continuous casting speed is controlled at 0.8 m / min" is adjusted to "the continuous casting speed is controlled at 1.0 m / min". Other operations of converter smelting, LF refining, RH vacuum treatment and bloom continuous casting are the same as in Example 1.

[0058] The finished product components of the embodiments of the present invention are shown in Table 1, and the low magnification structure ratings (rated according to YB / T 153) and rolled product non-metallic inclusions (rated according to method A of GB / T 10561) of the embodiments and comparative examples are detected in Tables 2 and 3.

[0059] Table 1 Finished product components (wt / %) and properties after heat treatment of Examples 1 to 3 and Comparative Examples 1 to 4

[0060]

[0061] Table 2 Low-magnification structure (grade) test results of Examples 1-3 and Comparative Examples

[0062]

[0063] Table 3 Non-metallic inclusion (grade) test results of the rolled materials prepared in Examples 1-3 and Comparative Examples

[0064] Non-metallic inclusion rating (level) A (coarse) A (fine) B (coarse) B (fine) C (coarse) C (fine) D (coarse) D (fine) DS Example 1 0.0 0.5 0.0 0.0 0.0 0.0 0.0 0.5 0.0 Example 2 0.0 0.5 0.0 0.0 0.0 0.0 0.0 0.5 0.0 Example 3 0.0 0.5 0.0 0.0 0.0 0.0 0.0 0.5 0.0 Comparative Example 3 0.0 0.5 0.0 0.5 0.0 0.0 0.5 1.0 2.5

[0065] From the above table data, it can be seen that in Comparative Example 1, the content of C element in the chemical composition was reduced, and the hardness of the product after heat treatment did not meet the requirements (the requirement is 58-62 HRC). In Comparative Example 2, the content of Si element in the chemical composition was reduced, the hardness did not meet the requirements, and fracture occurred during torsion and bending. In Comparative Example 3, due to the change of ladle during the pouring of the ladle, the height of the tundish liquid level was 400 mm, and slag entrainment problems occurred after the molten steel was impacted during the pouring of the next furnace, resulting in the DS inclusions in the steel exceeding the standard (the standard requirement is ≤ 2.0 grade). In Comparative Example 4, the shrinkage cavity of the low-magnification structure test reached grade 3, and central martensite structure appeared in the rolled material, affecting the use of the rolled material.

[0066] The raw materials and equipment used in the present invention are all common raw materials and equipment in the art without special instructions; the methods used in the present invention are all conventional methods in the art without special instructions. The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification made to the above embodiments based on the technical essence of the present invention is included in the protection scope of the present invention.

Claims

1. A high-strength and high-wear-resistant alloy tool steel, characterized in that: the chemical composition of the alloy tool steel is by weight percentage: [C] 0.72% - 0.74%, [Si] 1.52% - 1.58%, [Mn] 0.52% - 0.58%, [Cr] 1.05% - 1.10%, [Ni] 0.21% - 0.24%, [V] 0.16% - 0.18%, [Al] 0.025% - 0.035%, [P] ≤ 0.015%, [S] ≤ 0.010%, and the rest is Fe and inevitable impurities; the alloy tool steel is used for processing electric wood chisels; The smelting method of the high-strength and high-wear-resistant alloy tool steel includes the following specific steps: (1) Converter smelting: The converter is charged with 110 - 130 tons of hot metal and 10 - 30 tons of scrap steel. High-carbon drawing operation is adopted at the end of smelting. The tapped steel [C] ≥ 0.05%, the tapped steel [P] ≤ 0.015%, the tapping temperature is greater than 1620 - 1650 °C, the tapping time is 4 - 6 min. Deoxidizer, alloy, carburizer and slag materials are added in turn 30 s after tapping. Double-block operation is adopted after tapping is completed; (2) LF refining: LF refining adjusts the steel water composition to the target value and adjusts the temperature in place. Small argon stirring smelting is adopted throughout the refining process; (3) RH vacuum treatment: Argon is used as the lifting gas, and the lifting gas flow rate is 80 - 100 Nm 3 / h; after the vacuum degree is less than 120 Pa, keep the pressure for 15 min and then break the vacuum. Take a steel water sample. According to the sample analysis results, adjust the Al content by feeding aluminum wire, and then feed 50 - 100 m of calcium wire for modification treatment, and soft blow for 15 - 20 min; (4) Bloom continuous casting: Before continuous casting starts, the tundish is baked to ensure that the ladle temperature for the first casting heat is 1525 - 1545 °C, and the ladle temperature for continuous casting heats is 1500 - 1525 °C. After the tundish stops baking, argon is filled into it for 3 - 5 min; After starting casting, protective casting is carried out on the surface of the tundish steel liquid level throughout the process. The tundish is cast with an integral nozzle, and the casting superheat is controlled at 20 - 30 °C. Steel slag is left in the ladle after each heat of casting is completed; When changing ladles after each heat of casting is completed, ensure that the steel liquid level in the tundish is above 600 mm; The continuous casting drawing speed is controlled at 0.80 m / min, the return water temperature difference of the first cooling water is controlled at 4 - 6 °C, the secondary cooling specific water volume is 0.20 L / kg, the mold and the end electromagnetic stirring are started, and soft reduction is adopted at the solidification end. The bloom is slowly cooled in the pit, and the temperature when entering the pit is greater than 500 °C. It can only be taken out of the pit after the heat preservation time is greater than 42 hours.

2. A smelting method of the high-strength and high-wear-resistant alloy tool steel as described in claim 1, characterized in that: it includes converter smelting, LF refining, RH vacuum treatment, and bloom continuous casting; the specific steps are as follows: (1) Converter smelting The converter is charged with 110 - 130 tons of hot metal and 10 - 30 tons of scrap steel. High - carbon tapping operation is adopted at the end of smelting. The tapped steel has [C] ≥ 0.05% and [P] ≤ 0.015%. The tapping temperature is greater than 1620 - 1650 °C, and the tapping time is 4 - 6 min. Deoxidizers, alloys, carburizers and slag materials are added in sequence 30 s after the start of tapping. Double - stopper operation is adopted at the end of tapping; (2) LF refining The LF refining adjusts the composition of the molten steel to the target value and adjusts the temperature in place. Small - argon - gas stirring smelting is adopted throughout the refining process; (3) RH vacuum treatment Argon is used as the lifting gas, and the lifting - gas flow rate is 80 - 100 Nm³ / h. After the vacuum degree is less than 120 Pa, keep the pressure for 15 min and then break the vacuum. Take a steel - water sample. According to the analysis results of the sample, adjust the Al content by feeding aluminum wire, and then feed 50 - 100 m of calcium wire for modification treatment, and soft - blow for 15 - 20 min; (4) Bloom continuous casting Before the continuous - casting start - up, the tundish is baked to ensure that the ladle - hanging temperature of the start - up heat is 1525 - 1545 °C, and that of the continuous - casting heat is 1500 - 1525 °C. After the tundish stops baking, argon is filled into it for 3 - 5 min. During the whole process after start - up, protective casting is carried out on the surface of the tundish molten - steel level. The tundish is cast with an integral nozzle, and the casting superheat is controlled at 20 - 30 °C. After each heat of casting, steel slag is left in the ladle; When changing the ladle at the end of each heat of casting, ensure that the molten - steel level in the tundish is above 600 mm; The continuous - casting drawing speed is controlled at 0.80 m / min, the temperature difference of the return water of the first - stage cooling water is controlled at 4 - 6 °C, the specific water volume of the secondary cooling is 0.20 L / kg, the mold and the end - point electromagnetic stirring are started, light reduction is adopted at the solidification end - point, and the bloom is slowly cooled in a pit. The temperature when entering the pit is greater than 500 °C, and it can only be taken out of the pit after the heat - preservation time is greater than 42 hours.

3. The smelting method of the high - strength and high - wear - resistance alloy tool steel according to claim 2, characterized in that: In the step (1), the hot - metal composition requirements are [Si]: 0.50% - 0.80%, [P] ≤ 0.10%, [S] ≤ 0.030%, and the temperature is 1300 - 1400 °C; The double - stopper operation during tapping is to use a slide plate and a slag - dam cone to block the slag.

4. The smelting method of the high - strength and high - wear - resistance alloy tool steel according to claim 2, characterized in that: In the step (2), small - argon - gas stirring smelting is carried out throughout the refining process, and the argon - gas stirring intensity is 50 - 100 L / min.

5. The smelting method of the high - strength and high - wear - resistance alloy tool steel according to claim 2, characterized in that: In the step (4), protective casting is carried out on the surface of the tundish molten - steel level throughout the process. The first layer in contact with the molten steel for protective casting uses an alkaline covering agent, the second layer uses carbonized rice - husk ash, and there is no molten - steel exposure on the surface of the tundish.

6. The smelting method of the high - strength and high - wear - resistance alloy tool steel according to claim 2, characterized in that: In the step (4), 3 - 5 tons of steel slag are left in the ladle after each heat of casting, that is, after each ladle of casting, 3 - 5 tons of steel slag are left in the ladle; During the stable casting process of the tundish, the molten - steel level is 850 - 900 mm.

7. The smelting method of the high - strength and high - wear - resistance alloy tool steel according to claim 2, characterized in that: In the step (4), the bloom billet has a cross-section of 300mm×325mm, and the 1#-4# rolls are used for reduction at the solidification end. The reduction amounts are 2mm, 3mm, 3mm, and 4mm respectively, and the total reduction amount is 12mm.

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