Blanking method of high-speed tool steel and blank

Abstract

The invention provides a cogging method of high-speed tool steel and a blank, and relates to the technical field of high-speed tool steel hot working.The cogging method of the high-speed tool steel comprises the steps that a rapid forging hydraulic machine and precise forging and pressing equipment are preheated, the preheated rapid forging hydraulic machine is adopted for conducting primary forging on a steel ingot, and a blank semi-finished product is obtained; and carrying out secondary forging on the blank semi-finished product by using preheated rapid precise forging and pressing equipment to obtain a blank finished product. According to the cogging method of the high-speed tool steel, the steel ingot is forged through the rapid forging hydraulic press and the rapid precision forging and pressing equipment in sequence, the surface quality performance of the machined blank is excellent, the heating number in the cogging process of the high-speed tool steel can be effectively reduced, energy and time are effectively saved, and meanwhile the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of forging processes, and particularly to a method for blooming high-speed tool steel. At the same time, the present invention also relates to a billet processed by applying the method for blooming high-speed tool steel. Background Art

[0002] High-Speed Steel (HSS) is a tool and die material containing about 25% of high-carbon and high-alloy elements such as W, Mo, Cr, V, Si, Al, Co, etc., with characteristics such as high hardness, high wear resistance, high hot hardness, and strict carbide requirements. Due to its excellent hot hardness, wear resistance, and anti-tempering softening ability, it is widely used in high-temperature and high-load scenarios such as cutting tools and dies.

[0003] Due to the high-carbon and high-alloy composition of high-speed tool steel, it determines that the hot working process of high-speed tool steel, such as the blooming process, has the following characteristics:

[0004] (1) Since high-speed tool steel contains a large amount of alloying elements such as W, Mo, Cr, V, etc., these elements will produce a significant solid solution strengthening effect at high temperatures, increasing the strength and hardness of the steel, and the deformation resistance will also increase accordingly. The increase in deformation resistance will not only increase the energy consumption during the forging process but also easily lead to defects such as cracks and folds on the surface of the billet, seriously affecting the surface quality and subsequent processing performance of the billet.

[0005] (2) Since high-speed tool steel contains more alloying elements, it has higher requirements for heating temperature and cooling rate. If the heating temperature is too high or too low, it may cause the grains of the steel to be coarse, the structure to be uneven, or other defects to occur. Therefore, the forging temperature range of high-speed tool steel is small, and the heating temperature and holding time need to be strictly controlled during the forging process, which will increase the process difficulty and production cost. At the same time, the number of forging heats will increase, not only wasting a large amount of time and energy but also reducing the production efficiency. Summary of the Invention

[0006] In view of this, the present invention aims to propose a method for blooming high-speed tool steel to better save energy while ensuring the quality of the billet.

[0007] To achieve the above object, the technical solution of the present invention is realized as follows:

[0008] A method for blooming high-speed tool steel, the method comprising:

[0009] Preheating the quick forging hydraulic press and the precision forging equipment;

[0010] Using the preheated quick forging hydraulic press to perform the first forging on the ingot to obtain a semi-finished billet;

[0011] The semi-finished blank is subjected to a second forging using the preheated rapid precision forging equipment to obtain a finished blank.

[0012] Further, before the first forging of the ingot using the preheated rapid forging hydraulic press, the method further includes: placing the ingot in a heating furnace at a temperature of ≤450°C, heating it at a rate of ≤60°C / h to a temperature between 850°C and 880°C, holding for a time between 2.5 h and 3 h, and then heating it to a temperature between 1160°C and 1170°C, holding for a time between 5 h and 6 h.

[0013] Further, the anvil width ratio of the first forging is between 0.85 and 1.0; and / or, the stock width ratio of the first forging is between 1.0 and 1.2.

[0014] Further, the starting forging temperature of the first forging is between 1010°C and 1060°C, and the final forging temperature is ≥900°C; and / or, the tempering temperature during the first forging is between 1120°C and 1130°C, and the holding time is between 1.5 h and 2.0 h.

[0015] Further, the pass deformation of the first forging is between 15 mm and 25 mm; and / or, the forging ratio of the first forging is between 2.0 and 3.0.

[0016] Further, during the second forging, forging is carried out in sequence according to the forging method of circular blank, square blank, flat blank, square blank, and circular blank.

[0017] Further, the starting forging temperature of the second forging is between 980°C and 1050°C, and the final forging temperature is between 850°C and 920°C.

[0018] Further, during the second forging, the feeding speed is controlled between 1.5 m / min and 3 m / min; and / or, the forging ratio of the second forging is between 1.5 and 2.5.

[0019] Further, preheating the rapid forging hydraulic press includes: placing the first experimental steel in a heating furnace for heating, with the heating temperature ≥250°C and the heating time ≥1.5 h; clamping the heated first experimental steel by the chuck of the rapid forging hydraulic press, and making all the hammer anvils of the rapid forging hydraulic press contact the first experimental steel to start preheating, with the preheating time ≥0.5 h; and / or,

[0020] Preheating the precision forging equipment includes: placing the second experimental steel in a heating furnace for heating, with the heating temperature ≥ 250 °C and the heating time ≥ 1.5 h; clamping the heated second experimental steel with the chuck of the high-speed forging hydraulic press, and making all the hammers of the high-speed forging hydraulic press contact the second experimental steel to start preheating, with the preheating time ≥ 0.5 h.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] In the blooming method of the high-speed tool steel described in the present invention, preheating is an important step before forging. It can reduce the number of heating times during forging, reduce the risk of cracks generated inside the billet, ensure that the equipment reaches an appropriate working temperature during forging, thereby improving forging efficiency and the surface quality of the billet. First, use a preheated high-speed forging hydraulic press (abbreviated as fast forging machine) to perform the first forging on the ingot, and then use a preheated precision forging equipment (abbreviated as precision forging machine) to perform the second forging. The two types of equipment cooperate for forging, and the surface quality performance of the processed billet is excellent. It can effectively reduce the number of heating times during the blooming process of high-speed tool steel, effectively save energy and time. At the same time, it also improves the production efficiency.

[0023] The ingot is placed in a heating furnace with a temperature not exceeding 450 °C. This low starting temperature helps to reduce the thermal stress generated by the ingot due to rapid temperature rise, thereby avoiding the generation of cracks. The heating rate is controlled not to exceed 60 °C / h. This slower heating rate can ensure the uniform rise of the internal temperature of the ingot, avoiding non-uniform organization caused by local overheating or too large a temperature gradient. When the temperature of the ingot rises to between 850 °C and 880 °C, heat preservation treatment is carried out, and the heat preservation time is controlled between 2.5 h and 3 h. The purpose of this step is to further homogenize the internal temperature of the ingot, and at the same time, it is also beneficial to eliminate or reduce the microscopic segregation in the ingot and the stress caused by tissue transformation.

[0024] After intermediate heat preservation, the ingot continues to heat up to between 1160 °C and 1170 °C. This temperature range is the ideal temperature window for hot processing of high-speed tool steel, which can not only ensure good plastic deformation ability but also avoid the deterioration of the organization caused by overheating. Heat preservation is carried out within this temperature range for a long time of 5 h to 6 h, which can ensure that the internal temperature of the ingot is completely uniform, and at the same time, it is also beneficial to the refinement of grains and the homogenization of the organization.

[0025] The anvil width ratio refers to the ratio of the feeding amount of the upper anvil to the height of the forging before deformation during forging. An excessive anvil width ratio may cause surface cracking or serious folding and distortion of the forging, while an insufficient anvil width ratio may lead to insufficient deformation of the forging, affecting the internal structure and mechanical properties of the forging.

[0026] The blank width ratio refers to the ratio of the width of the blank before forging to the width of the blank after forging. If the blank width ratio is too small, excessive spreading of the blank may occur during forging, resulting in out-of-control shape. If the blank width ratio is too large, excessive shrinkage of the blank may occur during forging, resulting in insufficient dimensions or inaccurate shape.

[0027] During the first forging process, the starting forging temperature is between 1010°C and 1060°C. This temperature range can ensure that the material has sufficient plasticity and deformation ability, while avoiding the deterioration of the microstructure and the decline in properties caused by overheating. Starting forging within this temperature range is conducive to the uniform deformation of the material and the refinement of the internal microstructure. The finishing forging temperature is not lower than 900°C. Maintaining this relatively high finishing forging temperature helps to reduce the deformation resistance and internal stress during forging, and is also beneficial to the subsequent cooling and heat treatment processes. If the finishing forging temperature is too low, cracks and defective microstructures may be generated inside the material, affecting the quality and performance of the final product.

[0028] During the first forging process, the recommended tempering temperature is between 1120°C and 1130°C. This temperature range helps to eliminate the internal stress and microstructure defects generated during forging, while promoting the uniform distribution and refinement of carbides. The selection of the tempering temperature should be adjusted according to the material characteristics and process requirements to ensure the best microstructure and properties. The recommended holding time is between 1.5 h and 2.0 h, so that the holding time is sufficient to ensure uniform temperature inside the material, while promoting the full transformation of the microstructure and the uniform distribution of carbides. If the holding time is too short, the internal stress and microstructure defects may not be completely eliminated; if the holding time is too long, excessive softening of the material and decline in properties may occur.

[0029] During the first forging process, the magnitude of the pass deformation directly affects the degree of material deformation and the evolution of the internal microstructure. A smaller pass deformation may lead to low forging efficiency, while a larger pass deformation may increase the deformation resistance and internal stress of the material, and even cause cracks.

[0030] The forging ratio refers to the ratio of the cross-sectional area of the metal before and after deformation. The recommended forging ratio for the first forging is between 2.0 and 3.0. The selection of this range aims to ensure that the material obtains sufficient deformation to improve its internal microstructure and properties. The magnitude of the forging ratio has an important impact on the microstructure and properties of the material. A smaller forging ratio may not be able to fully break up the coarse carbide particles in the material and make them uniformly distributed, while a larger forging ratio may lead to excessive deformation of the material and the generation of internal cracks.

[0031] During the second forging process, forging is carried out in the order of circular billet, square billet, flat billet, square billet, and circular billet. The design of this forging sequence aims to optimize the deformation of the material, improve the internal structure, and enhance the shape accuracy and dimensional stability of the product.

[0032] As the starting stage of the second forging, the forging method of the circular billet can provide a relatively uniform and symmetrical initial shape. During forging, the material can flow more evenly, which helps to reduce the generation of internal stress and defects and provides a good foundation for the subsequent shape deformation.

[0033] Changing from the forging method of the circular billet to that of the square billet requires the material to deform in multiple directions. This multi-directional deformation helps to further break up the carbide particles in the material and make their distribution more uniform. The formation of the square billet also provides more possibilities for the subsequent shape deformation.

[0034] The forging of the flat billet mainly occurs in one direction of the material, resulting in significant compressive deformation in this direction. This compressive deformation helps to further refine the structure of the material and improve its properties. The formation of the flat billet can provide a good shape foundation for the subsequent forging of the square billet.

[0035] Forging the square billet again on the basis of the flat billet can further improve the internal structure and shape accuracy of the material. By forging the square billet multiple times, the size of the material can be gradually stabilized, and the dimensional fluctuations during the deformation process can be reduced, making full preparations for the formation of the final circular billet. Through the final forging of the circular billet, forgings with the required shape and dimensional accuracy can be obtained. The multiple deformations make the structure of the material more uniform and stable, which can better improve the properties of the forgings.

[0036] The starting forging temperature of the second forging is between 980°C and 1050°C. Within this temperature range, the metal is in the austenite region, having high plasticity and low deformation resistance. This enables the metal to undergo plastic deformation more easily during forging without prematurely generating cracks or fractures. At the same time, a slightly lower starting forging temperature compared to the first forging is beneficial for the fragmentation of carbides during forging, helping to obtain a more uniform organizational structure. During forging, the grains inside the metal will undergo rearrangement and refinement, thereby improving the mechanical properties and toughness of the material.

[0037] Although high temperature helps to improve the plasticity of metals, excessively high temperature will cause overheating of the metals, resulting in grain growth and a decrease in the mechanical properties of the materials. Therefore, controlling the initial forging temperature between 980°C and 1050°C can avoid the occurrence of overheating. The selection of the final forging temperature should ensure that the metal can be fully deformed during forging to achieve the expected size and shape. Within this temperature range, the metal still has a certain degree of plasticity and can continue to undergo plastic deformation.

[0038] If the final forging temperature is too low, the metal will become more brittle and prone to cracking during forging. Therefore, controlling the final forging temperature between 850°C and 920°C can avoid brittle fracture caused by too low temperature. Moreover, forging at an appropriate final forging temperature helps to further refine the grain structure inside the metal and improve the strength and toughness of the material.

[0039] The first experimental steel and the second experimental steel are placed in a heating furnace for heating. The heating temperature ≥ 250°C and the heating time ≥ 1.5 h are to ensure that the first experimental steel has sufficient heat capacity, which is conducive to fully heating the quick forging machine and the precision forging machine. And restricting the preset preheating time ≥ 0.5 h is also to improve the preheating effect on the quick forging machine and the precision forging machine.

[0040] Another object of the present invention is to provide a blank, which is made by the blanking method of high-speed tool steel as described above.

[0041] The blank of the present invention is prepared by adopting the blanking method of high-speed tool steel as above, which optimizes the internal organizational structure of the blank, refines the grains and makes their distribution uniform, improves both the mechanical properties and toughness. After a strictly controlled heating, forging and cooling process, the performance of the blank is stable and reliable, and can meet the usage requirements under various complex working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0043] Figure 1 It is a photo of the carbide non-uniformity of blank No. 1;

[0044] Figure 2 It is a photo of the carbide non-uniformity of blank No. 2;

[0045] Figure 3 It is a photo of the carbide non-uniformity of blank No. 3;

[0046] Figure 4 It is a photo of the carbide non-uniformity of blank No. 4;

[0047] Figure 5 Photograph of the maximum carbide particle size of blank No. 1

[0048] Figure 6 Photograph of the maximum carbide particle size of blank No. 2

[0049] Figure 7 Photograph of the maximum carbide particle size of blank No. 3

[0050] Figure 8 Photograph of the maximum carbide particle size of blank No. 4 Specific implementation manners

[0051] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0052] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0053] Due to the chemical composition of high-speed tools, the deformation resistance of high-speed tool steel is much higher than that of ordinary carbon steel. At 1000 °C, the deformation resistance of high-speed steel can reach 3-5 times that of ordinary carbon steel. Therefore, large-tonnage forging equipment is usually used for blooming.

[0054] In the prior art, the forging equipment commonly used for blooming high-speed tool steel is a quick forging press. The quick forging press is suitable for mass and high-efficiency forging production, such as upsetting and preliminary shaping of large steel ingots. The precision forging press is a relatively precise equipment, which is usually used in the subsequent processing after blooming, such as further shaping and finishing before rolling.

[0055] This embodiment relates to a method for blooming high-speed tool steel, and the method includes the following steps:

[0056] S101. Preheat the quick forging hydraulic press and the precision forging equipment;

[0057] S102. Use the preheated quick forging hydraulic press (hereinafter referred to as the quick forging press) to perform the first forging on the steel ingot to obtain a semi-finished blank;

[0058] S103. Use the preheated quick precision forging equipment (hereinafter referred to as the precision forging press) to perform the second forging on the semi-finished blank to obtain a finished blank.

[0059] By setting step S101, it can ensure that the equipment reaches an appropriate working temperature during forging, thereby improving the forging efficiency and the surface quality of the blank. By successively using the quick forging press and the precision forging press for blooming, the two equipment cooperate, and the surface quality performance of the processed blank is excellent, which can effectively reduce the number of heating times during the blooming of high-speed tool steel, effectively save energy and time, and at the same time, also improves the production efficiency.

[0060] As a preferred embodiment, in step S102, before the first forging of the ingot using a preheated quick forging hydraulic press, the method of this embodiment further includes placing the ingot in a heating furnace at a temperature of ≤450°C, heating it to a temperature between 850°C and 880°C at a rate of ≤60°C / h. For example, it can be 850°C, 860°C, 870°C, 880°C, etc. The holding time is between 2.5h and 3h. For example, it can be 2.5h, 2.7h, 3h, etc. Then, it is heated to a temperature between 1160°C and 1170°C. For example, it can be 1160°C, 1165°C, 1170°C, etc. The holding time is between 5h and 6h. For example, it can be 5h, 5.5h, 6h, etc.

[0061] As a preferred embodiment, in step S102, the anvil width ratio for the first forging is between 0.85 and 1.0. For example, it can be 0.85, 0.9, 0.95, 1.0, etc. In this embodiment, the anvil width ratio refers to the ratio of the upper anvil feed to the height of the forging before deformation. During forging, the length of the forging fed onto the anvil each time is called the feed amount L. When the width W of the upper anvil is equal to the feed amount L and the feed amount is greater than the width of the anvil, it is called full anvil feed. At this time, the anvil width ratio refers to the ratio of the width w of the upper anvil to the height H of the forging before deformation. In the case of non-full anvil feed, the anvil width ratio refers to the ratio of the feed amount L to the height H of the forging before deformation.

[0062] As a preferred embodiment, in step S102, the stock width ratio for the first forging is between 1.0 and 1.2. For example, it can be 1.0, 1.1, 1.2, etc.

[0063] As a preferred embodiment, in step S102, the starting forging temperature for the first forging is between 1010°C and 1060°C. For example, it can be 1010°C, 1030°C, 1045°C, 1060°C, etc. The final forging temperature is ≥900°C. It should be noted that the starting forging temperature is also called the initial forging temperature, which refers to the temperature at which forging begins. The final forging temperature refers to the temperature of the metal material at the end of the last forging operation during the forging process.

[0064] As a preferred embodiment, in step S102, the tempering temperature during the first forging is between 1120°C and 1130°C. For example, it can be 1120°C, 1125°C, 1130°C, etc. The holding time is between 1.5h and 2.0h. For example, it can be 1.5h, 1.6h, 1.8h, 2.0h, etc. Due to the limitation of the final forging temperature during the forging process, tempering treatment is required when the temperature of the forging is about to be lower than the final forging temperature.

[0065] As a preferred embodiment, in step S102, the pass deformation amount of the first forging is between 15 mm and 25 mm, such as 15 mm, 20 mm, 25 mm, etc. The pass deformation amount of forging refers to the dimensional change ratio of the blank before and after deformation in each pass (i.e., each forging operation) during the forging process.

[0066] In a preferred embodiment, during the forging process, the forging force is preferably between 1350 t and 1800 t, such as 1350 t, 1500 t, 1750 t, 1800 t, etc., and the deformation rate is 0.4 s-1 to 0.8 s-1.

[0067] As a preferred embodiment, in step S102, the forging ratio of the first forging is between 2.0 and 3.0, such as 2.0, 2.2, 2.5, 2.6, 2.8, 3.0, etc.

[0068] As a preferred embodiment, in step S103, during the second forging process, the forging is carried out in sequence according to the forging method of circular blank, square blank, flat blank, square blank, and circular blank.

[0069] It should be noted that a precision forging machine generally includes four hammers. The chuck can drive the semi-finished blank to rotate. While the semi-finished blank rotates, four hammers are used for forging, which belongs to the forging method of circular blank. When the semi-finished blank does not rotate and four hammers forge together, it belongs to the forging method of square blank. As for the forging method of flat blank, it is that the semi-finished blank does not rotate and a pair of hammers among the four hammers forge the semi-finished blank.

[0070] As a preferred embodiment, in step S103, during the second forging, the starting forging temperature is between 980 °C and 1050 °C, such as 980 °C, 990 °C, 1000 °C, 1050 °C, and the final forging temperature is between 850 °C and 920 °C, such as 850 °C, 870 °C, 890 °C, 905 °C, 920 °C, etc.

[0071] As a preferred embodiment, during the second forging process, the feeding speed is controlled between 1.5 m / min and 3 m / min, such as 1.5 m / min, 2 m / min, 2.5 m / min, 3 m / min, etc.

[0072] As a preferred embodiment, the forging ratio of the second forging is between 1.5 and 2.5, such as 1.5, 1.8, 2.0, 2.3, 2.5, etc.

[0073] As a preferred embodiment, in step S101, preheating the quick forging hydraulic press includes: placing the first experimental steel in a heating furnace for heating, with the heating temperature ≥ 250°C and the heating time ≥ 1.5 h; clamping the heated first experimental steel with the chuck of the quick forging hydraulic press, and making all the anvil hammers of the quick forging hydraulic press contact the first experimental steel to start preheating, with the preheating time ≥ 0.5 h.

[0074] As a preferred embodiment, in step S101, preheating the precision forging equipment includes: placing the second experimental steel in a heating furnace for heating, with the heating temperature ≥ 250°C and the heating time ≥ 1.5 h; clamping the heated second experimental steel with the chuck of the quick forging hydraulic press, and making all the hammer heads of the quick forging hydraulic press contact the second experimental steel to start preheating, with the preheating time ≥ 0.5 h.

[0075] The billet opening method of the high-speed tool steel in this embodiment can significantly improve the plasticity and deformation ability of the ingot by setting a reasonable heating process, making it easier to obtain the required shape and size during forging. By precisely controlling the heating temperature and holding time, defects such as cracks and folds inside the ingot can be avoided, thus ensuring the surface quality and internal structure of the billet finished product. In addition, a reasonable heating process can reduce energy consumption and time waste during forging, thereby improving production efficiency and reducing costs.

[0076] Design a special hot transfer trolley between the quick forging machine and the precision forging machine, and utilize the characteristic that the billet opening temperature requirement of the precision forging machine is not high to achieve hot transfer, which is conducive to reducing the number of heating passes.

[0077] For the existing high-speed tool steel, the forging temperature range of the quick forging machine is generally between 900°C and 1100°C. Due to the large number of alloying elements in the high-speed tool steel, its thermal conductivity is poor (the thermal conductivity coefficient is about 15 W / m·K - 20 W / m·K). Before forging, it usually needs to be preheated in three stages (heating up in three stages of 400°C, 800°C, and 1150°C, with the holding time ≥ 1.5 minutes / mm).

[0078] Next, the billet opening method of the high-speed tool steel in this embodiment will be described in combination with specific preparation examples and comparative examples.

[0079] Select 4 electroslag ingots produced by the electroslag remelting technology. The diameter of each electroslag ingot is φ315 mm and the length is 1500 mm, numbered 1 to 4 in sequence. The quick forging machine selects a quick forging machine with a model of 20 MN, and the precision forging machine selects a precision forging machine with a model of SX55.

[0080] Preheat the quick forging machine and the precision forging machine respectively. The heating temperature of the first experimental steel and the second experimental steel is 250°C, the heating time is 1.5 h, and the preheating time is 0.5 h.

[0081] No. 1: Open the billet according to the existing method

[0082] Place the No. 1 ingot in a heating furnace at a temperature of 300°C, heat it up to 850°C at a rate of ≤60°C / h, keep it warm for 2.5 h, then heat it up to 1160°C, and keep it warm for 5 h.

[0083] Throughout the process, use a fast forging machine to break the ingot and forge the ingot into a blank with a diameter of φ140 mm. The anvil width ratio is 0.85, the material width ratio is 1.0, the forging start temperature is 1010°C, the tempering temperature is 1120°C, the holding time is 1.5 h, and the pass deformation amount is 15 mm.

[0084] No. 2: Open the ingot according to the method of this embodiment

[0085] Place the No. 2 ingot in a heating furnace at a temperature of 300°C, heat it up to 850°C at a rate of ≤60°C / h, keep it warm for 2.5 h, then heat it up to 1160°C, and keep it warm for 5 h.

[0086] For the first forging, forge the ingot into a semi-finished blank with a diameter between φ220 mm and φ240 mm. The anvil width ratio is 0.85, the material width ratio is 1.0, the forging start temperature is 1010°C, the tempering temperature is 1120°C, the holding time is 1.5 h, the pass deformation amount is 15 mm, and the forging ratio is between 2.0 and 3.0.

[0087] For the second forging, forge the semi-finished blank into a blank with a diameter of φ140 mm. The forging start temperature is between 980°C and 1050°C, the feeding speed is controlled between 1.5 m / min, and the forging ratio is 1.5.

[0088] During the second forging process, forge in sequence according to the forging methods of round blank φ215 mm, square blank 170 mm×170 mm, flat blank 170 mm×143 mm, square blank 150 mm×150 mm, round blank φ170 mm, and round blank φ140 mm.

[0089] No. 3: Open the ingot according to the method of this embodiment

[0090] Place the No. 3 ingot in a heating furnace at a temperature of 300°C, heat it up to 850°C at a rate of ≤60°C / h, keep it warm for 2.5 h, then heat it up to 1160°C, and keep it warm for 5 h.

[0091] For the first forging, forge the ingot into a semi-finished blank with a diameter between φ220 mm and φ240 mm. The anvil width ratio is 0.85, the material width ratio is 1.0, the forging start temperature is 1010°C, the tempering temperature is 1120°C, the holding time is 1.5 h, the pass deformation amount is 15 mm, and the forging ratio is between 2.0 and 3.0.

[0092] The second forging processes the semi-finished blank into a blank with a diameter of φ140mm. The starting forging temperature is between 980°C and 1050°C, the feeding speed is controlled within 1.5m / min, and the forging ratio is 1.5.

[0093] During the second forging process, forging is carried out successively according to the forging method of the circular blank.

[0094] No. 4: The blank is bloomed according to the method of this embodiment, with the same parameters as No. 2, except that the quick forging machine and the precision forging machine are not preheated.

[0095] For the blanks prepared from the ingots numbered 1 - 4, in accordance with the requirements of flaw detection grade A or above in GB / T4162 - 2008 "Ultrasonic Testing Method for Forged and Rolled Steel Bars", the carbide non-uniformity in the tissue detection meets the requirements of GB / T9943, reaching the level of 6A, and the maximum carbide particle size meets the requirements of GB / T9943 ≤27μm. The test results are shown in Table 1.

[0096] Table 1:

[0097]

[0098] Analyzing the data in Table 1, it can be seen that for the ingot No. 1, since the existing method is used for blooming, a total of 5 heating passes are required, while for the ingots No. 2 to No. 4, since the method of this embodiment is used for blooming, 3 heating passes are required, which can reduce 1 to 2 heating passes compared with the existing method.

[0099] For the ingot No. 2, since the forging method during the second forging process is multi-directional forging, the properties of the blank prepared from the ingot in terms of ultrasonic flaw detection, carbide non-uniformity, maximum carbide particle size, etc. are superior to those of the ingots No. 3 and No. 4.

[0100] For the ingot No. 5, since the quick forging machine and the precision forging machine are not preheated, the number of blooming heating passes increases by 1 compared with the ingot No. 2.

[0101] This embodiment also relates to a blank, which is processed and manufactured by the above-mentioned blooming method for high-speed tool steel, and has excellent material quality, tissue uniformity, performance stability, etc. By strictly controlling process parameters such as heating temperature, deformation amount, cooling rate, etc., the quality and performance of the blank can be ensured to meet the use requirements under various complex working conditions.

[0102] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A blooming method for high-speed tool steel, characterized in that, The method includes: Preheating a rapid forging hydraulic press and a precision forging equipment; Using the preheated rapid forging hydraulic press to perform the first forging on an ingot to obtain a semi-finished blank; Performing the second forging on the semi-finished blank by using the preheated precision forging equipment to obtain a finished blank.

2. The billet-opening method for high-speed tool steel according to claim 1, wherein: Before performing the first forging on the ingot by using the preheated rapid forging hydraulic press, the method further includes: Placing the ingot in a heating furnace at a temperature of ≤450°C, heating it to a temperature between 850°C and 880°C at a rate of ≤60°C / h, keeping it warm for a time between 2.5 h and 3 h, and then heating it to a temperature between 1160°C and 1170°C, keeping it warm for a time between 5 h and 6 h.

3. The billet-opening method for high-speed tool steel according to claim 1, wherein: The anvil width ratio of the first forging is between 0.85 and 1.0; and / or, The material width ratio of the first forging is between 1.0 and 1.

2.

4. The billet-opening method for high-speed tool steel according to claim 3, wherein: The starting forging temperature of the first forging is between 1010°C and 1060°C, and the final forging temperature is ≥900°C; and / or, The tempering temperature during the first forging is between 1120°C and 1130°C, and the holding time is between 1.5 h and 2.0 h.

5. The billet-opening method for high-speed tool steel according to claim 3, wherein: The pass deformation amount of the first forging is between 15 mm and 25 mm; and / or, The forging ratio of the first forging is between 2.0 and 3.

0.

6. The billet-opening method for high-speed tool steel according to claim 1, wherein: During the second forging, forging is sequentially performed in the forging manner of circular billet, square billet, flat billet, square billet, and circular billet.

7. The billet-opening method for high-speed tool steel according to claim 6, wherein: The starting forging temperature of the second forging is between 980°C and 1050°C, and the final forging temperature is between 850°C and 920°C.

8. The billet-opening method for high-speed tool steel according to claim 6, wherein: During the second forging, the feeding speed is controlled between 1.5 m / min and 3 m / min; and / or, The forging ratio of the second forging is between 1.5 and 2.

5.

9. The billet-opening method for high-speed tool steel according to any one of claims 1-8, wherein: Preheating the rapid forging hydraulic press includes: placing a first experimental steel in a heating furnace for heating, with the heating temperature ≥250°C and the heating time ≥1.5 h; clamping the heated first experimental steel by the chuck of the rapid forging hydraulic press, and making all the hammer anvils of the rapid forging hydraulic press contact the first experimental steel to start preheating, with the preheating time ≥0.5 h; and / or, Preheating the precision forging equipment includes: placing the second experimental steel in a heating furnace for heating, with the heating temperature ≥ 250 °C and the heating time ≥ 1.5 h; clamping the heated second experimental steel with the chuck of the quick forging hydraulic press, and making all the hammers of the quick forging hydraulic press contact the second experimental steel to start preheating, with the preheating time ≥ 0.5 h.

10. A billet, characterized in that: The billet is made by the bloom ingot method of high-speed tool steel as described in any one of claims 1-9.

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