Alloy tool steel and pilot melting process thereof

Abstract

The present invention provides an alloy tool steel and a pilot smelting process thereof, and relates to the field of metal smelting; the process is a same-furnace smelting process for multiple alloy samples with different compositions, and by calculating the remaining amount of molten steel in the crucible after the first alloy sample is cast with the molten steel of the initial target composition of the vacuum induction furnace, and the remaining amount of molten steel in the crucible after any subsequent sample casting, the target component whose content is increased or decreased in the next alloy sample is added with the target component, and the industrial pure iron is added for dilution to accurately control the composition of each alloy sample after the first casting. The present invention can produce no less than 5 alloy samples with different compositions in one furnace, and can not only control the size of each casting sample, but also accurately control the composition of each alloy sample by calculating the remaining molten steel, and does not limit the content change trend of each component in the molten steel before and after each casting, thereby improving the research and development efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of metal smelting, and in particular to an alloy tool steel and a pilot smelting process thereof. Background Art

[0002] Melting under vacuum conditions can effectively avoid the oxidation and burning of alloy elements during atmospheric melting and pouring, achieve precise control of chemical composition, and improve the purity of the alloy. Small-capacity vacuum induction furnaces are widely used in the product development stage under this background. In the product development stage, it is often necessary to carry out a series of comparative tests to compare the performance changes caused by changes in certain elements, hoping that other elements remain unchanged; however, the existing technical solutions have many problems in practical applications, such as large differences in the composition of samples produced in different furnaces, many restrictions on the production of samples with different compositions in the same furnace, and serious waste of test materials.

[0003] In the existing scheme, the one-furnace dual-component smelting process of patent CN107245636B includes a melting period, a refining period, an alloying stage 1, a pouring stage 1, an alloying stage 2 and a pouring stage 2, which is used to solve the problem that the components that are expected to be fixed in different furnaces of the same component requirements are quite different, and there is a problem that the performance changes caused by the comparison of different components are misleading; when this scheme is applied, it is required that some elements of the later-casting sample are higher than those of the first-casting sample, and it is limited to the production of samples of two components, which limits the scope of application of the production process. However, it was found during the implementation process that there are restrictions on the application of this scheme, that is, in the actual pilot process, it is usually necessary to compare multiple components, and there is a situation where some elements of the later-casting sample are higher than those of the first-casting sample, while other elements are lower than those of the first-casting sample; it is impossible to achieve that some elements of the later-casting sample are lower than those of the first-casting sample at the same time, which is not conducive to the serial comparative test in product development. In addition, the test material often only needs 20 to 30 kg, and the weight of the sample produced by the above-mentioned smelting process is too large, which not only wastes materials and increases R&D costs, but also is not conducive to the flexibility of test operations and reduces R&D efficiency. Summary of the invention

[0004] The present invention aims to provide an alloy tool steel and a pilot smelting process thereof, which utilizes a vacuum induction furnace and achieves simultaneous casting of five or more alloy samples with different compositions in one furnace by precisely controlling the remaining amount of molten steel in a crucible.

[0005] To achieve the above object, the present invention proposes the following technical solutions:

[0006] In a first aspect, a pilot melting process for alloy tool steel is provided. The pilot melting process is a same-furnace melting process for a plurality of alloy samples with different compositions. The composition of each alloy sample after the first pouring is accurately controlled by calculating the remaining amount of molten steel in the crucible after each sample pouring in a vacuum induction furnace and by adding additional component alloys and additional industrial pure iron for dilution.

[0007] Furthermore, the process of calculating the remaining amount of molten steel in the crucible after each sample pouring in the vacuum induction furnace to accurately control the composition of each alloy sample is as follows:

[0008] The remaining amount of molten steel in the crucible is calculated by using the total amount of the furnace put into the furnace and the total weight of the alloy sample cast using the sample mold accurately weighed by the weighing unit;

[0009] According to the alloy composition of the next cast alloy sample, the type of alloy to be added and its weight are determined, including: when the content of several target components is higher than the content of components in the current molten steel, the corresponding target component elements are added; when the content of several target components is higher than the content of components in the current molten steel and the content of several other target components is lower than the content of components in the current molten steel, the molten steel in the crucible is diluted with industrial pure iron until the molten steel composition meets the requirements for reducing the target component content, and then the corresponding target component elements are added until the requirements for increasing the target component content are met.

[0010] Further, the following steps are included:

[0011] 1) Batching and pretreatment: Calculate the target amount of each raw material according to the composition of the first target molten steel, the raw material composition and the total amount of raw materials, remove the surface oxide layer of each raw material, and dry the raw materials;

[0012] 2) Mold preparation: several sample molds are made according to the sample weight target, and several sample molds are equipped with weighing units at the bottom and placed on the mold cart; the weighing units are reset to zero;

[0013] 3) Loading: All the raw materials corresponding to the first target molten steel composition are loaded into the crucible of the vacuum induction furnace, and the air in the furnace is extracted to make the pressure in the furnace reach 10-20 Pa;

[0014] 4) Electric refining: according to the smelting process curve, electricity is supplied until the raw materials are completely melted and enter the refining stage;

[0015] 5) Power-off film formation: After refining, the power is turned off until the steel liquid surface forms a film, and argon is filled into the furnace to make the pressure inside the furnace reach 95000~100000 Pa;

[0016] 6) Alloying: Add the remaining raw materials into the crucible in order, and turn on the power to melt the alloy and complete homogenization;

[0017] 7) Sampling and composition fine-tuning: Sampling and analyzing the chemical composition of the molten steel, and fine-tuning the composition according to the actual situation until the composition of the molten steel meets the composition requirements of the first target molten steel;

[0018] 8) Temperature measurement and pouring: Measure the temperature of the molten steel before pouring to ensure that the temperature of the molten steel is 1550-1560°C. Pour with electricity until the first sample mold is filled to obtain the first alloy tool steel;

[0019] 9) Power-off weighing: read the value of the weighing unit to determine the remaining amount of molten steel in the crucible;

[0020] 10) Power transmission and secondary alloying: The power transmission is 20-50 kW. The type and weight of the alloy to be added are determined according to the composition requirements of the second target molten steel and the remaining amount of molten steel in the crucible, and the alloy is melted and kept warm after being added. The process of determining the type and weight of the alloy to be added includes: when the content of several target components is higher than the content of the components in the current molten steel, the corresponding target component elements are added; when the content of several target components is higher than the content of the components in the current molten steel and the content of several other target components is lower than the content of the components in the current molten steel, the molten steel in the crucible is diluted with industrial pure iron until the molten steel composition meets the requirements of reducing the target component content, and then the corresponding target component elements are added until the requirements of increasing the target component content are met;

[0021] 11) Temperature measurement and pouring: Measure the temperature of the molten steel before pouring to ensure that the temperature of the molten steel is 1550-1560°C; pour under power until the second sample mold is filled to obtain the second alloy tool steel;

[0022] 12) Power-off weighing: read the value of the weighing unit to determine the remaining amount of molten steel in the crucible;

[0023] 13) Repeat steps 9) to 12) until all alloy samples are cast.

[0024] Furthermore, the raw materials are carbon particles, metallic chromium, polysilicon, metallic manganese, ferroboron alloy and industrial pure iron, wherein the mass percentage of boron element in the ferroboron alloy is 17%.

[0025] Furthermore, the composition of the target molten steel corresponding to each of the alloy samples satisfies the following mass percentages of the chemical components: C 0.65-0.85 wt.%, Mn 0.85-0.95 wt.%, Si 1.15-1.35 wt.%, Cr 0.80-1.00 wt.%, B 0.0010-0.0020 wt.%, and the remainder is Fe and unavoidable impurity elements.

[0026] Furthermore, the refining parameters of the refining process in step 4) are: furnace pressure of 10-20 Pa, refining temperature of 1570-1580° C., and refining time of 15-17 min.

[0027] Furthermore, the weighing unit in step 2) is an electronic platform scale;

[0028] The process of configuring a weighing unit at the bottom of the sample mold and placing it on a mold cart is as follows: placing an electronic platform scale on the mold cart, the weighing platform of the electronic platform scale having the same size as the table top of the mold cart; placing an ingot mold tray of the same size on the weighing platform of the electronic platform scale, and placing a number of the sample molds on the ingot mold tray.

[0029] Furthermore, the pilot smelting process produces no less than 5 alloy samples with different compositions in one furnace.

[0030] In a second aspect, an alloy tool steel is provided, which is produced by smelting using the pilot smelting process of the alloy tool steel mentioned above.

[0031] Furthermore, the alloy tool steel includes the following components in mass percentage: C 0.65-0.85%, Mn 0.85-0.95%, Si 1.15-1.35%, Cr 0.80-1.00%, B 0.0010-0.0020%, and the remainder is Fe and unavoidable impurity elements.

[0032] It can be seen from the above technical solutions that the technical solutions of the present invention have the following beneficial effects:

[0033] The alloy tool steel and pilot smelting process disclosed in the present invention are a same-furnace smelting process for multiple alloy samples with different compositions. By calculating the remaining amount of molten steel in the crucible after the first alloy sample is poured with molten steel of the initial target composition in the vacuum induction furnace, and the remaining amount of molten steel in the crucible after any subsequent sample pouring, the target component whose content increases or decreases in the next alloy sample is added, and industrial pure iron is added for dilution to accurately control the composition of each alloy sample after the first pouring. The present invention can produce no less than 5 alloy samples with different compositions in one furnace, which can not only control the size of each poured sample, but also does not limit the content change trend of each component before and after each pouring, thereby improving research and development efficiency. Specifically:

[0034] (1) Through the process design of producing 5 or more alloy samples with different chemical compositions in the same furnace, the problem of misjudgment of product performance when other components also change due to the inability to accurately produce comparison products containing only changes in the target composition during the series comparison test in the product development stage is solved. At the same time, a large-capacity vacuum induction furnace is used to produce multiple samples in one furnace to solve the problem that the amount of material produced in each furnace is far more than the demand, which wastes costs, is inconvenient to operate, and affects R&D efficiency.

[0035] (2) The composition of the next cast alloy sample is controlled by adding target metal and diluting the sample, so as to solve the problem that one or several elements of the later cast sample can only be higher than those of the earlier cast sample when producing samples of different compositions in the same furnace, thereby improving the applicability of the smelting process of this scheme.

[0036] (3) An electronic platform scale connected to the weight display outside the furnace through a wire is placed under the chassis of the sample mold. Before pouring, argon gas is filled into the furnace to make the pressure inside the furnace reach 95,000 to 100,000 Pa. After pouring, the power is turned off to avoid the influence of vacuum conditions and electromagnetic induction on weight measurement, and then the weight of the poured sample is accurately measured, ultimately achieving the purpose of accurately controlling the chemical composition; solving the problem that when five or more samples of different compositions are produced in the same furnace, there is a cumulative error in the remaining amount of molten steel in the crucible after each sample is poured, which makes it difficult to control the composition.

[0037] 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.

[0038] The foregoing and other aspects, embodiments and features of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings are not drawn to scale according to actual reference objects. In the accompanying drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the present invention will be described by way of example and with reference to the accompanying drawings, in which:

[0040] Figure 1 This is the pilot melting process curve of the alloy tool steel according to the embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment 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 meaning understood by people with general skills in the field to which the present invention belongs.

[0042] 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.

[0043] Based on the dual-component melting process disclosed in the prior art, which can simultaneously cast two alloy samples of different compositions in one furnace, it is required that the content of certain elements of the later-cast sample can be higher than that of the first-cast sample. However, in the actual pilot process, it is usually necessary to compare multiple components, and there is also a situation where the change trend of some element contents of the later-cast sample is opposite. Therefore, in order to solve the above problems, the present invention proposes an alloy tool steel and a pilot melting process thereof, which uses a vacuum induction furnace to simultaneously cast five or more alloy samples of different compositions with standard weights, and by optimizing the casting process, the atmosphere in the furnace and the power distribution method, the remaining amount of molten steel in the crucible is accurately controlled, the composition of the alloy sample is accurately controlled, and the change trend of the element content of the later-cast sample is no longer restricted.

[0044] Specifically, the pilot melting process of alloy tool steel disclosed in the present invention is characterized by comprising the following steps:

[0045] 1) Batching and pretreatment: according to the composition of the first target molten steel, the composition of the raw materials and the total amount of the raw materials, the target amount of each raw material is calculated, the surface oxide layer of each raw material is removed, such as industrial pure iron shot blasting to remove rust, and the raw materials are dried; in the embodiment, the total amount of raw materials is controlled to be 152 kg, and the total amount added to the crucible is 150-152 kg;

[0046] 2) Mold preparation: several sample molds are made according to the sample weight target, and several sample molds are equipped with weighing units at the bottom and placed on the mold cart; the weighing units are reset to zero;

[0047] The specific structure is as follows: an electronic platform scale is placed on the mold cart, the weighing platform of the electronic platform scale has the same size as the table top of the mold cart, and the electronic platform scale is connected to the weight display outside the furnace through a wire; an ingot mold tray of the same size is placed on the weighing platform of the electronic platform scale, and several sample molds are placed on the ingot mold tray. When all the sample molds are placed, the electronic platform scale is reset to zero.

[0048] 3) Loading: All the raw materials corresponding to the first target molten steel composition are loaded into the crucible of the vacuum induction furnace, and the air in the furnace is extracted to make the pressure in the furnace reach 10-20 Pa;

[0049] 4) Electric refining: According to the smelting process curve, electricity is supplied until the raw materials are melted and enter the refining period; during the refining period, the vacuum degree and refining temperature of the vacuum induction furnace are controlled and set according to the composition of the prepared target alloy sample.

[0050] 5) Power-off film formation: After refining, the power is turned off until the steel liquid surface forms a film, and argon is filled into the furnace to make the pressure inside the furnace reach 95000~100000 Pa;

[0051] 6) Alloying: Add the remaining raw materials into the crucible in order, and turn on the power to melt the alloy and complete homogenization;

[0052] 7) Sampling and composition fine-tuning: Sampling and analyzing the chemical composition of the molten steel, and fine-tuning the composition according to the actual situation until the composition of the molten steel meets the composition requirements of the first target molten steel;

[0053] 8) Temperature measurement and pouring: Measure the temperature of the molten steel before live pouring to ensure that the temperature of the molten steel is 1550-1560°C. Pour the molten steel until the first sample mold is filled to obtain the first alloy tool steel.

[0054] 9) Power-off weighing: read the value of the weighing unit to determine the remaining amount of molten steel in the crucible;

[0055] The above process involves filling the furnace with argon before pouring to make the pressure inside the furnace reach 95,000 to 100,000 Pa, and turning off the power supply after pouring. The purpose of this operation is to avoid the influence of vacuum conditions and electromagnetic induction on the weight measurement of the poured molten steel by the electronic platform scale, thereby ensuring the accurate measurement of the weight of the poured alloy sample, and ultimately achieving the purpose of accurately controlling the chemical composition of each pouring after the first alloy tool steel.

[0056] 10) Power transmission and secondary alloying: The power transmission is 20-50 kW. The type and weight of the alloy to be added are determined according to the composition requirements of the second target molten steel and the remaining amount of molten steel in the crucible, and the alloy is melted and kept warm after being added. The process of determining the type and weight of the alloy to be added includes: when the content of several target components is higher than the content of the components in the current molten steel, the corresponding target component elements are added, that is, the alloy containing the target component elements is added; when the content of several target components is higher than the content of the components in the current molten steel and the content of several other target components is lower than the content of the components in the current molten steel, the molten steel in the crucible is diluted with industrial pure iron until the molten steel composition meets the requirements of reducing the target component content, and then the corresponding target component elements are added until the requirements of increasing the target component content are met;

[0057] 11) Temperature measurement and pouring: Measure the temperature of the molten steel before live pouring to ensure that the temperature of the molten steel is 1550-1560 ℃. Pour the molten steel until the second sample mold is filled to obtain the second alloy tool steel;

[0058] 12) Power-off weighing: read the value of the weighing unit to determine the remaining amount of molten steel in the crucible;

[0059] 13) Repeat steps 9) to 12) until all alloy samples are poured. In some cases, the subsequent pouring process after the second alloy tool steel is poured may not perform the sampling and temperature measurement steps, and the temperature of the molten steel may be directly controlled by controlling the power supply.

[0060] The alloy tool steel and the pilot smelting process disclosed in the present invention are further specifically introduced below in conjunction with specific embodiments.

[0061] The embodiment of the present invention aims to prepare the following alloy tool steel by the above-mentioned pilot smelting process, wherein the alloy tool steel comprises the following components by mass percentage: C 0.65-0.85%, Mn 0.85-0.95%, Si 1.15-1.35%, Cr0.80-1.00%, B 0.0010-0.0020%, and the balance is Fe and unavoidable impurity elements; the preparation raw materials are selected from carbon particles, metallic chromium, polycrystalline silicon, metallic manganese, ferroborium alloy and industrial pure iron, wherein carbon particles, metallic chromium, polycrystalline silicon and metallic manganese are single materials, and the mass percentage of boron element in ferroborium alloy is 17%; the refining parameters of the alloy tool steel refining process of the composition are: furnace pressure 10-20 Pa, refining temperature 1570-1580 ° C, and refining time 15-17 min.

[0062] Example 1

[0063] This embodiment aims to prepare 6 kinds of alloy tool steels with different compositions. The designed chemical compositions of the 6 kinds of alloy tool steels during initial design are shown in Table 1 below.

[0064] Table 1 Chemical composition requirements of alloy tool steel / wt.%

[0065]

[0066] The specific smelting steps are as follows:

[0067] 1) Ingredients: The raw materials are industrial pure iron, carbon particles, metallic chromium, polysilicon, metallic manganese and ferroboron alloy. The element content of carbon particles, metallic chromium, polysilicon and metallic manganese is considered to be 100%, and the content of boron in ferroboron alloy is 17%. The amount of each raw material added is calculated based on the target composition of the alloy tool steel component 1 combined with the chemical composition of the raw materials. The results are shown in Table 2 below. The total amount of raw materials is 150 kg.

[0068] Table 2 Raw material addition amount / kg

[0069]

[0070] 2) Raw material pretreatment: Dry the raw materials at 150°C to fully remove moisture, and use industrial pure iron shot blasting to remove rust.

[0071] 3) Mould preparation: Place an electronic platform scale on the mould trolley. The platform scale has the same size as the mould trolley table. Place an ingot mould tray of the same size on the electronic platform scale. Place 6 30 kg grade sample moulds on the ingot mould tray. After all moulds are placed, reset the platform scale.

[0072] 4) Charging: Put all industrial pure iron, carbon particles, polysilicon and metallic chromium into the crucible of the vacuum induction furnace.

[0073] 5) Vacuum: Extract the air in the furnace so that the pressure inside the furnace reaches 20 Pa.

[0074] 6) Power on: According to Figure 1 The process curve shown is for power supply.

[0075] 7) Refining: During refining, the furnace pressure is 20 Pa, the refining temperature is 1570 ℃, and the refining time is 16 min.

[0076] 8) Power-off filming: The power is turned off until filming forms on the surface of the molten steel.

[0077] 9) Filling with argon: Fill the furnace with argon to make the pressure inside the furnace reach 100,000 Pa.

[0078] 10) First alloy tool steel alloying: Add metal manganese and ferroboron alloy into the crucible in sequence, and apply electricity to melt the alloy completely and complete homogenization.

[0079] 11) Sampling and composition fine-tuning: Take samples to analyze the chemical composition of the molten steel, and make composition fine-tuning according to the actual situation to ensure that the composition of the molten steel meets the design composition 1. The specific composition is shown in Table 3 below.

[0080] 12) Temperature measurement and pouring: Measure the temperature of the molten steel before live pouring to ensure that the temperature of the molten steel is 1550°C. Live pouring is performed until the first sample mold is filled to obtain the first alloy tool steel.

[0081] 13) Weighing during power failure: Turn off the power and read the value on the electronic platform scale. The value is 30.1 kg, and the remaining amount of molten steel in the crucible is 119.9 kg.

[0082] Table 3 Measured value of the first alloy tool steel / wt.%

[0083]

[0084] 14) Power transmission and alloying of the second alloy tool steel: The power transmission is 30 kW. The type and weight of the alloy to be added are determined based on the composition requirements of the design composition 2 and the remaining amount of molten steel in the crucible. The actual amount of carbon particles added is 0.036 kg.

[0085] 15) Sampling and composition fine-tuning: Take samples to analyze the chemical composition of the molten steel, and make composition fine-tuning according to the actual situation to ensure that the composition of the molten steel meets the design composition 2. The specific composition is shown in Table 4 below.

[0086] Table 4 Measured value of the second alloy tool steel / wt.%

[0087]

[0088] 16) Temperature measurement and pouring: After the carbon particles are fully melted, keep the temperature for 3 minutes. Measure the temperature of the molten steel before pouring to ensure that the temperature of the molten steel is 1550°C. Pour with electricity until the second sample mold is filled to obtain the second alloy tool steel.

[0089] 17) Weighing during power failure: Turn off the power and read the value on the electronic platform scale. The value is 30 kg, and the remaining amount of molten steel in the crucible is 89.9 kg.

[0090] 18) Power transmission and alloying of third alloy tool steel: The power transmission is 30 kW. The type and weight of alloy to be added are determined according to the composition requirements of design composition 3 and the remaining amount of molten steel in the crucible. The actual amount of carbon particles added is 0.027 kg.

[0091] 19) Casting: After the carbon particles are fully melted, keep the temperature for 3 minutes and cast with electricity until the third sample mold is filled to obtain the third alloy tool steel.

[0092] 20) Weighing during power failure: Turn off the power and read the value on the electronic platform scale. The value is 29.8 kg, and the remaining amount of molten steel in the crucible is 60.1 kg.

[0093] 21) Power transmission fourth alloy tool steel alloying: the power transmission is 30 kW. The type and weight of alloy to be added are determined according to the composition requirements of design composition 4 and the remaining amount of molten steel in the crucible. The actual amount of carbon particles added is 0.018 kg.

[0094] 22) Casting: After the carbon particles are fully melted, keep the temperature for 3 minutes and cast with electricity until the fourth sample mold is filled to obtain the fourth alloy tool steel.

[0095] 23) Weighing during power failure: Turn off the power and read the value on the electronic platform scale. The value is 30.0 kg, and the remaining amount of molten steel in the crucible is 30.1 kg.

[0096] 24) Power transmission: The power transmission capacity is 25 kW;

[0097] 25) The second batching is as shown in Table 5 below.

[0098] Table 5 Amount of raw materials added for the second batching / kg

[0099]

[0100] 26) Alloying and pouring of the fifth alloy tool steel: Add all the raw materials added for the second time into the furnace, keep warm for 8 minutes after full melting, and pour with electricity until the fifth sample mold is filled to obtain the fifth alloy tool steel.

[0101] 27) Weighing during power failure: Turn off the power and read the value on the electronic platform scale. The value is 30.2 kg and the remaining amount of molten steel in the crucible is 29.8 kg.

[0102] 28) Power transmission and alloying of the sixth alloy tool steel: The power transmission is 20 kW. The type and weight of the alloy to be added are determined based on the composition requirements of the design composition 6 and the remaining amount of molten steel in the crucible. The actual amount of carbon particles added is 0.009 kg.

[0103] 29) Casting: After the carbon particles are fully melted, keep the temperature for 3 minutes and cast with electricity until the sixth sample mold is filled to obtain the sixth alloy tool steel.

[0104] 30) Demolding: Demolding was performed the next day, and the weight and chemical composition of the samples were measured. The weight of the samples is shown in Table 6 below, and the chemical composition is shown in Table 7 below.

[0105] Table 6 Weight of each alloy sample / kg

[0106]

[0107] Table 7 Chemical composition of each alloy sample / wt.%

[0108]

[0109] As shown in Tables 1 to 7 above, the alloy tool steel and pilot melting process disclosed in the present invention can simultaneously cast five or more alloy samples of different compositions in one furnace, and the weight of a single sample is controlled within the range of 30 kg; and, by calculating the remaining amount of molten steel in the crucible after each sample casting in the vacuum induction furnace, the process is no longer limited to the element content of the later cast alloy sample must be higher than that of the previously cast sample, and the change trend of the content of each element in the alloy sample before and after each casting can be adjusted. Based on the fact that there is an error in the remaining amount of molten steel in the crucible after each casting, which increases the complexity of controlling the composition of the later cast alloy sample, the present invention adds an electronic platform scale of the same size connected to the display outside the furnace by a wire under the sample mold, combines the optimized casting process, the change of vacuum and argon atmosphere in the furnace, and the change of the power distribution mode during the casting process, accurately controls the remaining amount of molten steel in the crucible, and finally achieves the technical effect of accurate control of the composition of all alloy samples.

[0110] 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. A pilot melting process for alloy tool steel, characterized in that: The steps include: 1) Batching and pretreatment: Calculate the target amount of each raw material according to the composition of the first target molten steel, the raw material composition and the total amount of raw materials, remove the surface oxide layer of each raw material, and dry the raw materials; 2) Mold preparation: several sample molds are made according to the sample weight target, and several sample molds are equipped with weighing units at the bottom and placed on the mold cart; the weighing units are reset to zero; 3) Loading: All the raw materials corresponding to the first target molten steel composition are loaded into the crucible of the vacuum induction furnace, and the air in the furnace is extracted to make the pressure in the furnace reach 10-20 Pa; 4) Electric refining: according to the smelting process curve, electricity is supplied until the raw materials are completely melted and enter the refining stage; 5) Power-off film formation: After refining, the power is turned off until the steel liquid surface forms a film, and argon is filled into the furnace to make the pressure inside the furnace reach 95000~100000 Pa; 6) Alloying: Add the remaining raw materials into the crucible in order, and turn on the power to melt the alloy and complete homogenization; 7) Sampling and composition fine-tuning: Sampling and analyzing the chemical composition of the molten steel, and fine-tuning the composition according to the actual situation until the composition of the molten steel meets the composition requirements of the first target molten steel; 8) Temperature measurement and pouring: Measure the temperature of the molten steel before pouring to ensure that the temperature of the molten steel is 1550-1560°C. Pour with electricity until the first sample mold is filled to obtain the first alloy tool steel; 9) Power-off weighing: read the value of the weighing unit to determine the remaining amount of molten steel in the crucible; 10) Power transmission and secondary alloying: The power transmission is 20-50 kW. The type and weight of the alloy to be added are determined according to the composition requirements of the second target molten steel and the remaining amount of molten steel in the crucible, and the alloy is melted and kept warm after being added. The process of determining the type and weight of the alloy to be added includes: when the content of several target components is higher than the content of the components in the current molten steel, the corresponding target component elements are added; when the content of several target components is higher than the content of the components in the current molten steel and the content of several other target components is lower than the content of the components in the current molten steel, the molten steel in the crucible is diluted with industrial pure iron until the molten steel composition meets the requirements of reducing the target component content, and then the corresponding target component elements are added until the requirements of increasing the target component content are met; 11) Temperature measurement and pouring: Measure the temperature of the molten steel before pouring to ensure that the temperature of the molten steel is 1550-1560°C; pour under power until the second sample mold is filled to obtain the second alloy tool steel; 12) Power-off weighing: read the value of the weighing unit to determine the remaining amount of molten steel in the crucible; 13) Repeat steps 9) to 12) until all alloy samples are cast.

2. The pilot melting process of alloy tool steel according to claim 1, characterized in that: The raw materials are carbon particles, metallic chromium, polysilicon, metallic manganese, ferroboron alloy and industrial pure iron, wherein the mass percentage of boron element in the ferroboron alloy is 17%.

3. The pilot melting process of alloy tool steel according to claim 1, characterized in that: The composition of the target molten steel corresponding to each of the alloy samples satisfies the following mass percentages of each chemical component: C 0.65-0.85wt.%, Mn 0.85-0.95wt.%, Si 1.15-1.35 wt.%, Cr 0.80-1.00 wt.%, B 0.0010-0.0020 wt.%, and the remainder is Fe and unavoidable impurity elements.

4. The pilot melting process of alloy tool steel according to claim 3, characterized in that: The refining parameters of the refining process in step 4) are: furnace pressure of 10-20 Pa, refining temperature of 1570-1580° C., and refining time of 15-17 min.

5. The pilot melting process of alloy tool steel according to claim 1, characterized in that: The weighing unit in step 2) is an electronic platform scale; The process of configuring a weighing unit at the bottom of the sample mold and placing it on a mold cart is as follows: placing an electronic platform scale on the mold cart, the weighing platform of the electronic platform scale has the same size as the table top of the mold cart, and the electronic platform scale is connected to a weight display outside the furnace through a wire; placing an ingot mold tray of the same size on the weighing platform of the electronic platform scale, and placing a number of the sample molds on the ingot mold tray.

6. The pilot melting process of alloy tool steel according to claim 1, characterized in that: The pilot smelting process produces no less than 5 alloy samples with different compositions in one furnace.

7. An alloy tool steel, characterized in that: The alloy tool steel is prepared by the pilot smelting process of the alloy tool steel according to any one of claims 1 to 6.

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