Slender air valve alloy bar and anti-deformation method thereof

Abstract

The invention relates to a slender air valve alloy bar and an anti-deformation method thereof, and belongs to the technical field of air valve alloy manufacturing. According to the anti-deformation method, a cast ingot is obtained through vacuum induction smelting and electroslag remelting; a rolled blank is obtained through forging and rolling; carrying out solid solution treatment, cold straightening treatment and tempering treatment; carrying out two times of cold straightening and two times of low-temperature aging treatment; and finally, rough machining, low-temperature aging and finish machining are conducted, and the air valve alloy bar is obtained. The method of combining three times of low-temperature aging and three times of straightening is utilized, meanwhile, parameters in the machining process are controlled, the air valve alloy bar with the diameter smaller than 30 mm and the length larger than 2 m can be prepared, the straightness of the air valve alloy bar is 0.045 mm / m or below, and the straightness of the air valve alloy bar still meets the requirement of being smaller than 0.1 mm / m after the air valve alloy bar is stored for one year.

Description

Technical Field

[0001] The present invention relates to the technical field of valve alloy manufacturing, in particular to a slender valve alloy bar and an anti-deformation method thereof. Background Art

[0002] The valve, also known as the air valve, is an important component in fuel and gas engines. Its function is to input air into the engine and discharge the exhaust gas after combustion.

[0003] Valve steel and alloys are categorized by material composition. To conserve material, valve alloys are typically manufactured in lengths exceeding two meters. However, due to space constraints within internal combustion engines and engine weight requirements, valve diameters cannot be excessively large, typically around 20 mm. Consequently, valve alloy bars are typically slender components, subject to deformation during processing and preparation.

[0004] Furthermore, after forming, valve alloy bars may be stored in warehouses for a period of time depending on production needs. Without anti-deformation treatment, these slender valve alloys can deform after prolonged storage, complicating subsequent processing. Furthermore, deformation can appear in the finished product, seriously impacting product quality. Therefore, anti-deformation processes during the processing of slender parts are crucial to ensuring the final quality and dimensional stability of the parts. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a slender valve alloy bar and its anti-deformation method, which can not only reduce the deformation of the valve alloy bar during processing and ensure the dimensional accuracy of the valve alloy during use; it can also effectively prevent the problem of deformation during long-term storage and extend the service life of the valve alloy bar.

[0006] In one aspect, the present invention provides a method for preventing deformation of an elongated valve alloy bar, comprising the following steps:

[0007] S1: smelting, ingots are obtained by vacuum induction smelting and electroslag remelting;

[0008] S2: hot deformation, obtaining rolled blanks through forging and rolling;

[0009] S3: solution treatment, cold straightening and tempering treatment are then carried out;

[0010] S4: Two more cold straightening and two more low-temperature aging treatments;

[0011] S5: Finally, rough machining, low-temperature aging and finishing are performed to obtain the valve alloy bar.

[0012] Furthermore, the straightness of the obtained valve alloy rod is below 0.045 mm / m, and the straightness is less than 0.1 mm / m after being stored for one year.

[0013] Furthermore, the temperature of the low-temperature aging is 40 to 80° C., and the time of the low-temperature aging is 15 to 20 days.

[0014] Furthermore, the low-temperature aging process uses foundry sand.

[0015] Furthermore, during the rough machining process, the cutting depth is 4.00-5.50 mm, the feed rate is 0.10-0.30 mm / r, and the cutting speed is 25-35 m / min;

[0016] After rough processing, leave a 0.30 to 0.80 mm margin on the surface of the bar.

[0017] Furthermore, during the finishing process, the turning depth is 1.00-1.50 mm, the feed rate is 0.02-0.08 mm / r, and the cutting speed is 120-190 m / min.

[0018] Furthermore, during the rough machining and the fine machining, the cutting tool is a titanium carbonitride-based cemented carbide cutting tool, and the cutting tool composition is Ti(C,N): 46%+Ta: C5.5%+WC: 10.5%+Co: 8%+Ni: 30%.

[0019] Furthermore, the valve alloy rod has a diameter less than 30 mm and a length greater than 2 m.

[0020] Furthermore, the valve alloy rod is an austenitic valve alloy, and its chemical composition is as follows by weight: 0.01-0.08%, Si: 0.1-0.4%, Mn: 0.50-1.00%, P: ≤0.020%, S: ≤0.020%, Cr: 16.00-19.00%, Ni: 23.0-27.0%, Al: 1.00-2.50%, Ti: 2.10-3.20%, Nb: 0.50-1.50%, V: 0.10-0.40%, Zr: 0.005-0.025%, Ce: 0.001-0.05%, and the rest is Fe and unavoidable impurities.

[0021] On the other hand, the present invention provides a slender valve alloy bar, which is prepared by the anti-deformation method of the present invention.

[0022] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0023] 1. The present invention utilizes a method combining three low-temperature aging treatments with three straightening treatments to minimize the combined effects of thermal stress, structural stress, and deformation stress generated during the heat treatment and straightening processes. This solves the problem of excessive deformation of slender parts or bars after long-term storage and improves the dimensional stability of valve alloy bars. Furthermore, by combining roughing and finishing with a cutting method and controlling the machining parameters, deformation of slender valve alloys during machining is avoided, thereby improving the product qualification rate.

[0024] 2. The low-temperature aging temperature of the present invention is 40-80°C, the low-temperature aging time is 15-20 days, and the low-temperature aging process is completed in the foundry sand, that is, the low-temperature aging is carried out using the residual heat of the foundry sand. On the one hand, it can save energy and reduce production costs; on the other hand, during the long-term low-temperature aging process, no obvious changes in the structure and performance will occur, only the segregation of individual atoms inside will occur, but the previously accumulated stress can be eliminated, preventing deformation during the processing process and after long-term storage;

[0025] 3. The anti-deformation method provided by the present invention is used to prepare valve alloy bars. By combining three low-temperature aging processes with three straightening processes and controlling the parameters during the processing, valve alloy bars with a diameter of less than 30 mm and a length of more than 2 m can be prepared, and the straightness is 0.045 mm / m.

[0026] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0028] Figure 1 This is the metallographic structure diagram of the valve alloy bar according to Example 1 of the present invention. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0030] The valve, also known as the air valve, is an important component in fuel and gas engines. Its function is to input air into the engine and discharge the exhaust gas after combustion.

[0031] Valve steel and alloys are categorized by material composition. To conserve material, valve alloys are typically manufactured in lengths exceeding two meters. However, due to space constraints within internal combustion engines and engine weight requirements, valve diameters cannot be excessively large, typically around 20 mm. Consequently, valve alloy bars are typically slender components, subject to deformation during processing and preparation.

[0032] Furthermore, due to the stress generated during the manufacturing process, valve alloy bars often need to be stored for a period of time during actual production. This can lead to severe deformation of the bars over time, making subsequent processing difficult and making it impossible to guarantee the final quality and dimensional stability of the bars.

[0033] Therefore, the present invention provides a method for preventing deformation of an elongated valve alloy bar, comprising the following steps:

[0034] S1: smelting, ingots are obtained by vacuum induction smelting and electroslag remelting;

[0035] S2: hot deformation, obtaining rolled blanks through forging and rolling;

[0036] S3: solution treatment, cold straightening and tempering treatment are then carried out;

[0037] S4: Two more cold straightening and two more low-temperature aging treatments;

[0038] S5: Finally, rough machining, low-temperature aging and finishing are performed to obtain the valve alloy bar.

[0039] Compared with the prior art, the present invention, by combining three low-temperature aging treatments with three straightening treatments, eliminates to the greatest extent the combined thermal stress, structural stress, and deformation stress generated during the heat treatment and straightening processes. This solves the problem of excessive deformation of slender parts or bars after long-term storage, and improves the dimensional stability of valve alloy bars. Furthermore, by combining roughing and finishing with a cutting method and controlling the machining parameters, deformation of slender valve alloys during machining is avoided, thereby improving the product qualification rate.

[0040] The present invention utilizes a combination of three low-temperature aging cycles and three straightening cycles, while simultaneously controlling process parameters. This allows the production of valve alloy bars with diameters less than 30 mm and lengths greater than 2 m, achieving a straightness below 0.045 mm / m. Furthermore, even after one year of storage, the straightness still meets the requirement of less than 0.1 mm / m.

[0041] Specifically, the ingot is obtained by vacuum induction smelting and electroslag remelting.

[0042] It should be noted that, in the present invention, the smelting can adopt the existing vacuum induction smelting and electroslag remelting to prepare the ingot, which will not be described in detail here.

[0043] Specifically, during the hot deformation process, a rolled billet is obtained by forging and rolling;

[0044] It should be noted that while the microstructure and performance of the valve alloy bar can be guaranteed during the forging and rolling processes, thermal stress is generated in the resulting valve alloy bar, causing deformation and thus failing to meet straightness requirements. Therefore, subsequent steps are required to remove the thermal stress.

[0045] In the present invention, the control parameters during the forging process are: the starting forging temperature is 1150-1170° C., the final forging temperature is 930-950° C., and air cooling is performed after forging.

[0046] In the present invention, the control parameters during the rolling process are: the starting rolling temperature is 1130-1150° C., the finishing rolling temperature is 930-950° C., and air cooling is performed after rolling.

[0047] In the present invention, after rolling, the rolled blank is subjected to solution treatment, cold straightening treatment and tempering treatment. The solution treatment temperature is 980-1000°C, and the temperature is kept at this temperature for 1.0-1.5 hours before water cooling. The tempering treatment temperature is 740-760°C and the temperature is kept at this temperature for 4.5-5.0 hours.

[0048] It should be noted that metal materials inevitably experience thermal stress and structural stress during the heating and cooling process. Due to the effects of thermal stress and structural stress, different residual stresses are generated in the parts after heat treatment. When the stress exceeds the yield strength of the material, it will cause deformation. This deformation is particularly obvious for thin-walled parts or slender parts.

[0049] Thermal stress and structural stress are generated during forging, rolling, and heat treatment (i.e., solution treatment). These stresses accumulate and accumulate in the component. Existing methods only reduce internal stress through tempering, but this cannot effectively remove it. Internal stress persists during part processing or after a period of storage. This internal stress slowly releases, causing deformation and reduced part precision.

[0050] Therefore, the present invention adopts a method combining three cold straightening steps and three low-temperature aging steps, which can ensure that the internal stress of the material is released while ensuring that no obvious structural transformation occurs inside the material.

[0051] The entire processing process is: after solution treatment, the first cold straightening is carried out, then tempering treatment is carried out, followed by the second cold straightening, the first low-temperature aging, the third cold straightening and the second low-temperature aging; finally, rough machining, the third low-temperature aging and finishing are carried out.

[0052] It should be noted that in the present invention, a method combining three low-temperature aging and three straightening is adopted to remove stress to the maximum extent. The purpose or function of each stage is different. The purpose of the first cold straightening is to correct the deformation generated after solution cooling, the purpose of the second cold straightening is to correct the residual deformation after tempering, and the purpose of the third cold straightening is to correct the residual deformation after low-temperature aging. The first low-temperature aging is to relieve the internal stress existing after tempering, the second low-temperature tempering is to relieve the internal stress generated during the third cold straightening process, and the third aging is to relieve the internal stress generated during the rough machining process.

[0053] Specifically, the temperature of the low-temperature aging is 40-80° C., and the time of the low-temperature aging is 15-20 days.

[0054] The low temperature aging process uses foundry sand.

[0055] It should be noted that in the present invention, the temperature of low-temperature aging is crucial, as it is necessary to ensure that the internal stress of the material is released while also ensuring that no significant structural transformation occurs within the material. The present invention adopts a low-temperature, long-term aging method for aging treatment. The low-temperature aging temperature can be 40°C, 50°C, 60°C, 70°C, or 80°C, and the low-temperature aging time can be 15 days, 16 days, 17 days, 18 days, 19 days, or 20 days.

[0056] During the low-temperature aging process, the residual internal stress of the part will gradually decrease as the low-temperature aging time increases. After three low-temperature aging cycles, this internal stress can be eliminated to the maximum extent. As the low-temperature aging time increases, the internal stress can be further eliminated to meet higher dimensional accuracy requirements, but the extension of the time will lead to a decrease in work efficiency.

[0057] In the present invention, low-temperature aging, due to the relatively low temperature, only causes the segregation of individual atoms within the material, without causing significant changes in the structure and properties. However, it can eliminate previously accumulated stress. If the low-temperature aging temperature is higher than 80°C, the internal structure of the material will change, affecting the material properties. For example, the segregation of individual atoms will cause uneven material properties.

[0058] In the present invention, the low-temperature aging process adopts foundry sand, that is, the waste heat generated by the foundry sand is used for low-temperature aging. On the one hand, from the perspective of production cost, there is no need to additionally heat the parts, which can save resources and costs. At the same time, the waste heat of the foundry sand can be effectively reused. On the other hand, from the perspective of aging effect, the internal stress in the parts can be better or minimized, thereby ensuring the dimensional accuracy during processing or storage.

[0059] Specifically, during the rough machining process, the turning depth is 4.00-5.50 mm, the feed rate is 0.10-0.30 mm / r, and the cutting speed is 25-35 m / min;

[0060] After rough processing, leave a 0.30 to 0.80 mm margin on the surface of the bar.

[0061] Specifically, during the finishing process, the turning depth is 1.00-1.50 mm, the feed rate is 0.02-0.08 mm / r, and the cutting speed is 120-190 m / min.

[0062] It should be noted that during the part processing, deformation of the part will also occur. There are two main processes: one is when the part is clamped, and the other is during the part processing. When the part is clamped, the deformation mainly comes from the inconsistency between the clamping point and the support point.

[0063] During machining, parts are subjected to cutting forces, causing them to deform elastically in the direction of the force. To ensure a smooth surface finish, high cutting speeds are often used. Frictional heat generated between the tool and the part can have a greater impact on part deformation, especially for thin-walled parts. To prevent deformation, symmetrical machining is often employed to balance the stresses on opposing surfaces, achieving a stable state and a smooth surface.

[0064] In this invention, a clamping method using a single clamp and a single support is used before turning. A center rest is placed in the middle of the valve alloy bar to provide additional support. This increases the rigidity of the bar during machining and prevents machining errors caused by elastic deformation of the valve alloy. Furthermore, the clamping point is positioned as close as possible to the machining surface to increase the contact area between the bar and the fixture, effectively minimizing deformation of the bar.

[0065] In the present invention, a relatively fast cutting speed is adopted in the machining process. In the high-speed cutting process, since the chips are removed in a relatively short time, most of the cutting heat is taken away by the chips, thereby reducing the thermal deformation of the parts.

[0066] For deformation caused by frictional heat, a faster cutting speed can be selected. Because in high-speed cutting, the chips are removed in a relatively short time, and most of the cutting heat is carried away by the chips, reducing the thermal deformation of the parts. Secondly, in high-speed machining, the softening part of the cutting material is reduced, which can also reduce the machining deformation of the parts, which is conducive to ensuring the size and shape accuracy of the parts.

[0067] Therefore, the present invention adopts a smaller feed rate and a faster cutting speed. The feed rate for roughing is 0.1-0.3 mm / r, and the cutting speed is 25-35 m / min (which can be 25 m / min, 26 m / min, 27 m / min, 28 m / min, 29 m / min, 30 m / min, 31 m / min, 32 m / min, 33 m / min, 34 m / min, or 35 m / min); the feed rate for finishing is 0.05-0.1 mm / r, and the cutting speed is 120-190 m / min (which can be 120 m / min, 130 m / min, 140 m / min, 150 m / min, 160 m / min, 170 m / min, 180 m / min, or 190 m / min). The smaller feed rate ensures that the part is subjected to less tool extrusion pressure, and the faster cutting speed ensures less frictional heat, thereby ensuring the straightness of the slender valve alloy.

[0068] If the feed rate is too high during finishing, the product surface roughness will be unacceptable. If the feed rate is too low, production efficiency will be affected. If the cutting speed is too high, tool wear will be severe, resulting in frequent tool changes. If the cutting speed is too low, processing efficiency will also be affected.

[0069] Preferably, during the rough machining and the fine machining, the cutting tool is a titanium carbonitride-based cemented carbide cutting tool, and the cutting tool composition is Ti(C,N): 46% + Ta: C5.5% + WC: 10.5% + Co: 8% + Ni: 30%.

[0070] It should be noted that the cutting tool used in the present invention is a titanium carbonitride-based carbide tool, rather than a high-speed steel or ceramic tool. High-speed steel tools wear quickly and require frequent tool changes, while ceramic tools are more expensive. Titanium carbonitride-based carbide tools offer smoother machining and are better suited to both high- and low-speed turning operations.

[0071] Specifically, the valve alloy rod is a precipitation hardening austenitic valve alloy, and its chemical composition by weight percentage is: 0.01~0.08%, Si: 0.1~0.4%, Mn: 0.50~1.00%, P: ≤0.020%, S: ≤0.020%, Cr: 16.00~19.00%, Ni: 23.0~27.0%, Al: 1.00~2.50%, Ti: 2.10~3.20%, Nb: 0.50~1.50%, V: 0.10~0.40%, Zr: 0.005~0.025%, Ce: 0.001~0.05%, and the rest is Fe and unavoidable impurities.

[0072] It should be noted that in the present invention, the valve alloy bar is a precipitation-hardening austenitic valve alloy with an internal matrix structure of austenite. During solution cooling, carbides and intermetallic compounds (γ') precipitate in the valve alloy, inevitably increasing the volume of the alloy matrix. For valve alloys, during solution cooling, the surface cools first, increasing its volume while the core volume remains unchanged. Because the core hinders the surface volume increase, the surface experiences compressive stress while the core generates tensile stress. Consequently, due to the different specific heats of the austenitic matrix and the precipitates generated during solution cooling, structural stress is generated.

[0073] The valve alloy rod is longer, and the time difference of this phase change in the length direction is more obvious, especially the valve alloy rod with a length of more than 2m and a diameter of less than 30mm, which is more prone to deformation in the length.

[0074] Tempering can partially eliminate the structural stress, thermal stress, and deformation stress caused by solution treatment and straightening. However, some stress still remains within the valve alloy bar. After the valve alloy bar is processed into parts, the residual stress will gradually act on the parts during use, causing deformation of the processed parts after long-term storage or use, resulting in a decrease in the dimensional stability of the parts, affecting their continued use.

[0075] Therefore, the present invention adopts a method combining three cold straightening and three low-temperature aging. The residual internal stress inside the part will gradually decrease with the extension of the low-temperature aging time. After three low-temperature aging, this internal stress can be eliminated to the maximum extent, which can ensure that the internal stress is released and that no obvious structural transformation occurs inside.

[0076] In order to more clearly describe the present invention, it is further illustrated by the following examples and comparative examples.

[0077] Example 1

[0078] A method for preventing deformation of a slender valve alloy bar comprises the following steps:

[0079] S1: Smelting, ingots were obtained by vacuum induction smelting and electroslag remelting; 6 batches of ingots with different compositions were prepared, as shown in Table 1;

[0080] S2: hot deformation, obtaining Φ25×2500mm round bars by forging and rolling;

[0081] S3: solution treatment, first cold straightening and tempering treatment are carried out;

[0082] The temperature of the solution treatment is 990℃, which is kept for 1.5h and then water-cooled;

[0083] The tempering process is 750℃ and kept warm for 5.0h;

[0084] The cold straightening parameter is 180 kg force for 8 minutes;

[0085] S4: Two more cold straightening and two more low-temperature aging treatments;

[0086] The process or sequence is: second straightening, first low-temperature aging treatment, third straightening and second low-temperature aging treatment; the molding sand temperature is maintained at 40°C and the aging time is 20 days;

[0087] S5: Finally, rough machining, low-temperature aging, and fine machining are performed to obtain the valve alloy bar. The parameters of the rough machining and fine machining are shown in Table 3. During the rough machining and fine machining, a titanium carbonitride-based cemented carbide tool is used, and the tool composition is Ti(C,N): 46% + Ta: C5.5% + WC: 10.5% + Co: 8% + Ni: 30%.

[0088] Table 1 Chemical composition of the present invention (wt%)

[0089]

[0090] In the present invention, each furnace of ingots is produced into two bars of the same specifications, which are numbered sequentially. Table 2 shows the bar straightness test results at different stages, including the tempering stage before straightening, the tempering and straightening stage, and the low-temperature aging + straightening + low-temperature aging stage (i.e., before rough machining, i.e., step S4).

[0091] Table 2 Straightness results at different stages

[0092]

[0093] Straightness tests were conducted at different stages before rough machining. As shown in Table 2, before straightening, the straightness was relatively high, ranging from 0.85 to 1.85 mm / m, indicating severe deformation. After straightening, the straightness decreased slightly, ranging from 0.22 to 0.57 mm / m. After low-temperature aging, straightening, and low-temperature aging, the straightness further decreased, falling below 0.27 mm / m.

[0094] Table 3 Process parameter control

[0095]

[0096]

[0097] As can be seen from Table 3, by adopting the processing method provided by the present invention, the cutting depth, feed rate and cutting speed in rough processing and fine processing are controlled. Under their mutual cooperation, the straightness is further reduced and the straightness is maintained below 0.045 mm / m, which meets the requirements.

[0098] Table 4 Straightness of the bars after one year of storage (unit: mm / m)

[0099]

[0100] Table 4 compares the straightness of valve alloy bars produced using conventional processes after one year of storage, as described in the present invention. The conventional process involves straightening the valve alloy bars after solutionizing and tempering, and then directly machining them into bars using standard machining techniques. The straightness of the processed bars meets the required accuracy, less than 0.1 mm / m.

[0101] The table shows that after one year, the traditional method for manufacturing valve alloy bars lacks a low-temperature aging treatment, resulting in ineffective internal stress release. This leads to a significant increase in the bar's straightness, which no longer meets the requirement of greater than 0.1 mm / m. However, the method of the present invention, through three low-temperature aging treatments and appropriate machining processes, effectively reduces stress in the valve alloy bars, increases their dimensional stability, and prevents excessive deformation of these slender parts.

[0102] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for preventing deformation of slender valve alloy bars, characterized in that: The following steps are involved: S1: smelting, ingots are obtained by vacuum induction smelting and electroslag remelting; S2: hot deformation, obtaining rolled blanks through forging and rolling; S3: solution treatment, cold straightening and tempering treatment are then carried out; S4: Two more cold straightening and two more low-temperature aging treatments; S5: Finally, rough machining, low-temperature aging and finishing are performed to obtain the valve alloy bar.

2. The method for preventing deformation of an elongated valve alloy bar according to claim 1, characterized in that: The straightness of the obtained valve alloy rod is below 0.045 mm / m, and the straightness is less than 0.1 mm / m after being stored for one year.

3. The method for preventing deformation of an elongated valve alloy bar according to claim 1, characterized in that: The temperature of the low-temperature aging is 40 to 80° C., and the time of the low-temperature aging is 15 to 20 days.

4. The method for preventing deformation of an elongated valve alloy bar according to claim 3, wherein: The low temperature aging process uses foundry sand.

5. The method for preventing deformation of an elongated valve alloy bar according to claim 1, characterized in that: During the rough machining process, the turning depth is 4.00-5.50 mm, the feed rate is 0.10-0.30 mm / r, and the cutting speed is 25-35 m / min; After rough processing, leave a 0.30 to 0.80 mm margin on the surface of the bar.

6. The method for preventing deformation of an elongated valve alloy bar according to claim 1, characterized in that: During the finishing process, the turning depth is 1.00-1.50 mm, the feed rate is 0.02-0.08 mm / r, and the cutting speed is 120-190 m / min.

7. The method for preventing deformation of an elongated valve alloy bar according to claim 1, characterized in that: During the rough machining and the fine machining, the cutting tool is a titanium carbonitride-based cemented carbide cutting tool, and the cutting tool composition is Ti(C,N): 46%+Ta: C5.5%+WC: 10.5%+Co: 8%+Ni: 30%.

8. The method for preventing deformation of an elongated valve alloy bar according to claim 1, characterized in that: The valve alloy rod has a diameter less than 30 mm and a length greater than 2 m.

9. The method for preventing deformation of an elongated valve alloy bar according to claim 1, characterized in that: The valve alloy bar is an austenitic valve alloy, and its chemical composition by weight percentage is: 0.01-0.08%, Si: 0.1-0.4%, Mn: 0.50-1.00%, P: ≤0.020%, S: ≤0.020%, Cr: 16.00-19.00%, Ni: 23.0-27.0%, Al: 1.00-2.50%, Ti: 2.10-3.20%, Nb: 0.50-1.50%, V: 0.10-0.40%, Zr: 0.005-0.025%, Ce: 0.001-0.05%, and the rest is Fe and unavoidable impurities.

10. A slender valve alloy bar, characterized in that: The anti-deformation method is prepared by any one of claims 1 to 9.

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