Method for heat treatment of a crankshaft blank, crankshaft and use thereof

Abstract

The application discloses a heat treatment method of a crankshaft blank, a crankshaft and application of the crankshaft. The heat treatment method of the crankshaft blank comprises the following steps: (1) tempering treatment of the crankshaft blank: placing the crankshaft blank in a tempering furnace, heating to 620-680 DEG C, keeping for 2-3 hours, taking the crankshaft blank out of the tempering furnace, and air cooling to room temperature; (2) quenching and tempering of the crankshaft blank after the tempering treatment: placing the crankshaft blank air cooled to room temperature in a quenching furnace, heating to 840-860 DEG C, keeping for 80-100 minutes, cooling to 790-810 DEG C, keeping for 8-28 minutes, taking out of the furnace, placing the crankshaft blank in a quenching tank, cooling to room temperature, placing the crankshaft blank in a tempering furnace again, heating to 620-640 DEG C, keeping for 80-120 minutes, taking the crankshaft blank out of the tempering furnace, and water cooling. Thus, the heat treatment of the crankshaft blank by the above method can improve the defects such as folds of the crankshaft blank after forging, and significantly reduces the quenching crack ratio of the crankshaft blank.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal heat treatment process, in particular, to a heat treatment method of a crankshaft blank, a crankshaft and application thereof. BACKGROUND

[0002] The crankshaft is one of the important components inside the engine, which converts the up-and-down reciprocating motion of the exhaust piston into continuous rotary motion, thereby driving the output shaft of the engine and other key components to operate, and further driving the running of the vehicle. The crankshaft is crucial to the performance and reliability of the engine, and its quality directly affects the performance and service life of the engine. Some crankshaft blanks need to be processed after quenching and tempering. At the initial stage of production, due to lack of experience and other reasons, the blank after forging has folds or other defects, which are prone to quenching cracks during the quenching process. The crankshaft blank with quenching cracks can only be scrapped, and the quenching scrap rate sometimes reaches 3% or even higher, which is a serious loss due to high scrap rate.

[0003] Therefore, the heat treatment method of the crankshaft blank still needs to be improved. SUMMARY

[0004] The present application aims to at least partially alleviate or solve at least one of the above-mentioned problems.

[0005] In one aspect of the present application, a heat treatment method of a crankshaft blank is provided. In some embodiments of the present application, the heat treatment method of the crankshaft blank comprises the following steps: (1) tempering the crankshaft blank: placing the crankshaft blank in a tempering furnace, heating to 620-680℃, holding for 2-3h, removing the crankshaft blank from the tempering furnace, and air cooling to room temperature; (2) quenching and tempering the crankshaft blank after tempering: placing the crankshaft blank air-cooled to room temperature in a quenching furnace, heating to 840-860℃, holding for 80-100min, cooling to 790-810℃, holding for 8-28min, removing from the furnace, placing the crankshaft blank in a quenching tank, cooling to room temperature, and then placing the crankshaft blank in a tempering furnace, heating to 620-640℃, holding for 80-120min, removing the crankshaft blank from the tempering furnace, and water cooling. Thus, the heat treatment of the crankshaft blank using the above method can improve the folds and other defects of the crankshaft blank after forging, and significantly reduce the quenching crack rate of the crankshaft blank.

[0006] In some embodiments of the present application, in step (1), the heating time is 20-40min. Thus, it is beneficial to the uniform distribution of the internal temperature of the crankshaft blank, thereby reducing thermal stress and deformation.

[0007] In some embodiments of the present invention, in step (2), the time required to raise the temperature to 840°C to 860°C is 20 min to 40 min. This helps to reduce thermal stress during the quenching and tempering process, making the crankshaft blank less prone to defects such as deformation and cracks.

[0008] In some embodiments of the present invention, in step (2), after holding at 840°C to 860°C, the time required to cool down to 790°C to 810°C is 8 min to 28 min. This reduces the internal stress of the structure during quenching, thereby further reducing the proportion of crankshaft blank cracks.

[0009] In some embodiments of the present invention, in step (2), the quenching tank is filled with a quenching agent, which includes a water-based quenching agent.

[0010] In some embodiments of the present invention, in step (2), the crankshaft blank is placed in a tempering furnace and heated to 620°C to 640°C for 20 to 40 minutes. This facilitates a uniform temperature distribution in the crankshaft blank, thereby further reducing internal stress and cracks.

[0011] In some embodiments of the present invention, the material of the crankshaft blank includes at least one of 42CrMo and 40CrNiMo.

[0012] In some embodiments of the present invention, in step (1), the crankshaft blank is tempered in a mesh belt tempering furnace; and / or, in step (2), the quenching furnace is a mesh belt quenching furnace.

[0013] In another aspect, the present invention provides a crankshaft. In some embodiments of the present invention, the crankshaft is obtained by heat-treating a crankshaft blank using the heat treatment method described above, followed by machining the heat-treated crankshaft blank. Therefore, the crankshaft possesses excellent mechanical properties and is free from obvious defects such as cracks.

[0014] In another aspect, the present invention proposes the application of the aforementioned crankshaft in vehicles. The aforementioned crankshaft possesses excellent mechanical properties and is free from obvious defects such as cracks, making it suitable as a crankshaft for components such as engines in vehicles. Attached Figure Description

[0015] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0016] Figure 1 A photograph of the crankshaft blank is shown.

[0017] Figure 2The image shows a crankshaft blank that has cracked during quenching and is considered a defective product.

[0018] Figure 3 A flowchart of a method for heat treating a crankshaft blank according to an embodiment of the present invention is shown;

[0019] Figure 4 The process curve for tempering a crankshaft blank according to an embodiment of the present invention is shown;

[0020] Figure 5 The process curve for quenching and tempering a crankshaft blank according to an embodiment of the present invention is shown. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0022] A physical image of the crankshaft blank can be referenced. Figure 1 As mentioned earlier, the forged crankshaft blank may have creases or other defects (such as stress), which can easily lead to quenching cracks during the tempering process. For examples of quenched cracked crankshaft blanks, please refer to... Figure 2 As you can see, Figure 2 The crankshaft blanks in the test were cracked and could not meet the requirements for use in engine crankshafts, so they had to be scrapped. In related technologies, directly quenching and tempering the forged crankshaft blanks, or normalizing the crankshaft blanks before quenching and tempering, did not have a significant effect on improving the cracks. Normalizing treatment may even aggravate the quenching crack tendency of the crankshaft blanks, and the quenching crack ratio of the crankshaft blanks after heat treatment was still relatively high.

[0023] To at least partially alleviate or even solve the problem of high scrap rate due to quenching cracks in crankshaft blanks after tempering, this invention proposes a heat treatment method for crankshaft blanks. In some embodiments of this invention, reference is made to... Figure 3 The heat treatment method for crankshaft blanks may include the following steps:

[0024] (1) Temper the crankshaft blank.

[0025] In some embodiments, reference Figure 4The forged crankshaft blank can be placed in a tempering furnace and heated to 620℃~680℃, held for 2h~3h. For example, the temperature can be raised to 620℃, 630℃, 640℃, 650℃, 660℃, 670℃ or 680℃, held for 2h, 2.3h, 2.5h, 2.8h or 3h, and then the crankshaft blank can be removed from the tempering furnace and air-cooled to room temperature. Adding a high-temperature tempering process before quenching and tempering the crankshaft blank can reduce the stress after forging, thereby reducing the proportion of quenching cracks in the crankshaft blank after quenching and tempering.

[0026] In some embodiments of the present invention, in step (1), the heating time can be 20 min to 40 min, for example, the heating time can be 20 min, 25 min, 30 min, 35 min or 40 min. Thus, the crankshaft blank can be heated from room temperature to 650℃±30℃ at a suitable heating rate. During the heating process, the temperature inside the crankshaft blank rises uniformly and the temperature distribution is uniform, which is beneficial to reduce the stress after forging, thereby further reducing the risk of quenching cracks in the crankshaft blank after tempering.

[0027] In some embodiments of the present invention, in step (1), the crankshaft blank can be tempered in a mesh belt tempering furnace.

[0028] In some embodiments of the present invention, the material of the crankshaft blank may include at least one of 42CrMo and 40CrNiMo. In some specific embodiments of the present invention, the material of the crankshaft blank may be 42CrMo or 40CrNiMo. In other specific embodiments of the present invention, the material of the crankshaft blank may include 42CrMo and 40CrNiMo. Crankshaft blanks made of the above materials are prone to creases and other defects after forging, and are also prone to stress that is difficult to release. After conventional heat treatment methods (tempering directly after forging, or normalizing and tempering sequentially after forging), the scrap rate of quenching cracks is relatively high. Tempering can reduce the stress after forging, improve defects such as cracks, and thus help reduce the proportion of crankshaft blanks that crack after tempering.

[0029] (2) The crankshaft blank after tempering is quenched and tempered.

[0030] After tempering the forged crankshaft blank, it can be quenched and tempered.

[0031] In some embodiments of the present invention, in step (2), the crankshaft blank cooled to room temperature can be placed in a quenching furnace, heated to 840°C to 860°C, and held for 80 min to 100 min. For example, the crankshaft blank can be placed in a quenching furnace, heated to 840°C, 845°C, 850°C, 855°C or 860°C, and held for 80 min, 85 min, 90 min, 95 min or 100 min.

[0032] In some embodiments of the present invention, in step (2), after holding at 840°C to 860°C for a period of time, the temperature is lowered to 790°C to 810°C and held for 8 min to 28 min. For example, the temperature can be lowered to 790°C, 795°C, 800°C, 805°C or 810°C and held for 8 min, 10 min, 15 min, 17 min, 20 min, 22 min, 25 min or 28 min.

[0033] In some embodiments of the present invention, in step (2), after holding at 790°C to 810°C for a period of time, the crankshaft blank is removed from the furnace and slides into the quenching tank to cool to room temperature. Then, the crankshaft blank is placed in a tempering furnace and heated to 620°C to 640°C for 80 min to 120 min. For example, the temperature can be raised to 620°C, 625°C, 630°C, 635°C or 640°C in the tempering furnace and held for 80 min, 90 min, 100 min, 110 min or 120 min. After that, the crankshaft blank is removed from the tempering furnace and water-cooled.

[0034] During the quenching and tempering process, the temperature is first held at 840℃~860℃ for a period of time, and then the temperature is lowered to 790℃~810℃ and held at 790℃~810℃ for a period of time. By adjusting the quenching and tempering process parameters and lowering the quenching temperature, the internal stress of the structure during quenching can be reduced, which is conducive to further reducing the proportion of crankshaft blanks cracking after quenching and tempering.

[0035] In some embodiments of the present invention, in step (2), the time taken to raise the temperature to 840°C to 860°C can be 20 min to 40 min. For example, the time taken to raise the temperature to 840°C to 860°C can be 20 min, 25 min, 30 min, 35 min, or 40 min. Thus, the heating can be carried out at a suitable heating rate, avoiding stress caused by uneven heating of the crankshaft blank.

[0036] In some embodiments of the present invention, in step (2), after holding at 840°C to 860°C, the time required to cool down to 790°C to 810°C can be 8 min to 28 min. For example, the time required to cool down to 790°C to 810°C can be 8 min, 10 min, 15 min, 20 min, 25 min or 28 min.

[0037] In some embodiments of the present invention, in step (2), the quenching tank is filled with a quenching agent, which may include a water-based quenching agent. Therefore, the cooling rate of the water-based quenching agent is between that of water and quenching oil, allowing the crankshaft blank to cool to room temperature at a relatively gentle rate, which helps reduce quenching stress and prevents deformation or cracking of the crankshaft blank. In some specific embodiments of the present invention, the quenching agent in the quenching tank may be a water-based quenching agent produced by Derunbao Company.

[0038] In some embodiments of the present invention, in step (2), the crankshaft blank is placed in a tempering furnace, and the time required to heat it to 620°C to 640°C can be 20 min to 40 min. For example, the time required to heat it from room temperature to 620°C to 640°C can be 20 min, 25 min, 30 min, 35 min, or 40 min. Therefore, using a slower heating rate helps to improve the temperature uniformity inside the crankshaft blank, thereby helping to reduce stress.

[0039] In some embodiments of the present invention, in step (2), the quenching furnace can be a mesh belt quenching furnace.

[0040] In some specific embodiments of the present invention, reference is made to... Figure 5 The tempering of the crankshaft blank after tempering can include the following steps: the crankshaft blank, which has been air-cooled to room temperature, is placed into a mesh belt quenching furnace, heated to 850°C for 0.5 hours, held for 1.5 hours, cooled to 800°C for 0.3 hours, held for 0.3 hours, and then removed from the furnace and slid into a quenching tank (containing quenching agent) to cool to room temperature. The crankshaft blank is then placed into a tempering furnace, heated to 630°C for 0.5 hours, held for 2 hours, removed from the furnace and water-cooled, and then slid into a material box.

[0041] The occurrence of quenching cracks in crankshaft blanks during the quenching and tempering process is mainly due to defects such as stress and cracks present after forging. These defects are unavoidable and can only be remedied by subsequent heat treatment processes to reduce the proportion of quenching cracks. To address this, this invention focuses on two aspects: First, adding a high-temperature tempering process before quenching and tempering eliminates the stress in the crankshaft blank after forging, thereby reducing the risk of quenching cracks during the subsequent quenching and tempering process. Second, adjusting the quenching and tempering process parameters, lowering the quenching temperature from 840℃~860℃ for a period of time to 800℃, and then holding at that temperature for another period, thereby reducing the internal stress in the microstructure during quenching and further reducing the risk of quenching cracks during the quenching and tempering process.

[0042] In some embodiments of the present invention, after the crankshaft blank is quenched and tempered, performance testing and flaw detection can be performed on the crankshaft blank. Performance testing may include hardness testing, metallographic analysis, and mechanical property testing; flaw detection refers to detecting whether there are any quenched cracks in the quenched and tempered crankshaft blank.

[0043] In this invention, by tempering and quenching the forged crankshaft blank, the risk of quenching cracks during the quenching and tempering process of the crankshaft blank can be reduced, the quenching crack scrap rate of the crankshaft blank can be reduced, and losses can be minimized.

[0044] In another aspect of the invention, a crankshaft is provided. In some embodiments of the invention, the crankshaft can be obtained by heat-treating a crankshaft blank using the heat treatment method described above, followed by machining the heat-treated crankshaft blank. Therefore, the crankshaft has good mechanical properties and is free from obvious cracks and other defects.

[0045] In some embodiments of the present invention, machining the heat-treated crankshaft blank may include trimming (removing excess material generated during forging), shaping (adjusting the shape and size of the crankshaft to ensure it meets design requirements), and precision machining (such as turning, milling, drilling, etc. to ensure the accuracy and dimensions of the crankshaft).

[0046] In another aspect, the invention proposes the application of the aforementioned crankshaft in a vehicle. In some embodiments of the invention, the crankshaft can be used as a component inside a vehicle engine to convert the reciprocating motion of the exhaust piston into continuous rotational motion, thereby driving the engine's output shaft and other key components to operate, and ultimately driving the vehicle. In some embodiments of the invention, the crankshaft can be used as a component of the engine in a gasoline-powered vehicle, an electric vehicle, or a hybrid vehicle.

[0047] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments below are merely illustrative and do not limit the scope of the invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the materials and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the later embodiments, conditions and methods known in the art can be used for processing.

[0048] Example 1

[0049] In Example 1, the crankshaft blank used is the crankshaft blank of BYD 1.5T hybrid passenger vehicle, the material is 42CrMo, the weight of a single piece is 11.8 kg, and the processing quantity is 1000 pieces.

[0050] High-temperature tempering treatment of crankshaft blanks: The crankshaft blanks are placed in a mesh belt tempering furnace, heated to 650℃ in 0.5 hours, held at that temperature for 2 hours, and then air-cooled to room temperature after being taken out of the furnace.

[0051] The crankshaft blank after tempering is quenched and tempered: the crankshaft blank, which has been air-cooled to room temperature, is placed in a mesh belt quenching furnace, heated to 850°C for 0.5 hours, held for 1.5 hours, cooled to 800°C for 0.3 hours, held for 0.3 hours, and then removed from the furnace and slid into a quenching tank (containing water-based quenching agent produced by Derunbao Company) to cool to room temperature. The crankshaft blank is then placed in a tempering furnace, heated to 630°C for 0.5 hours, held for 1.5 hours, removed from the furnace and water-cooled, and then slid into a material box.

[0052] Example 2

[0053] In Example 2, the crankshaft blank used is the crankshaft blank of BYD 1.5T hybrid passenger vehicle, with a single piece weight of 11.8 kg and a processing quantity of 1000 pieces.

[0054] High-temperature tempering treatment of crankshaft blanks: The crankshaft blanks are placed in a mesh belt tempering furnace, heated to 620℃ for 20 minutes, held at that temperature for 2.5 hours, and then air-cooled to room temperature after being taken out of the furnace.

[0055] The crankshaft blank after tempering is quenched and tempered: the crankshaft blank, which has been air-cooled to room temperature, is placed in a mesh belt quenching furnace, heated to 850°C for 0.5 hours, held for 1.5 hours, cooled to 800°C for 0.3 hours, held for 0.3 hours, and then removed from the furnace and slid into a quenching tank (containing water-based quenching agent produced by Derunbao Company) to cool to room temperature. The crankshaft blank is then placed in a tempering furnace, heated to 630°C for 0.5 hours, held for 1.5 hours, removed from the furnace and water-cooled, and then slid into a material box.

[0056] Example 3

[0057] In Example 3, the crankshaft blank used is the crankshaft blank of BYD 1.5T hybrid passenger vehicle, with a single piece weight of 11.8 kg and a processing quantity of 1000 pieces.

[0058] High-temperature tempering treatment of crankshaft blanks: The crankshaft blanks are placed in a mesh belt tempering furnace, heated to 680℃ for 40 minutes, held for 3 hours, and then air-cooled to room temperature after being taken out of the furnace.

[0059] The crankshaft blank after tempering is quenched and tempered: the crankshaft blank, which has been air-cooled to room temperature, is placed in a mesh belt quenching furnace, heated to 850°C for 0.5 hours, held for 1.5 hours, cooled to 800°C for 0.3 hours, held for 0.3 hours, and then removed from the furnace and slid into a quenching tank (containing water-based quenching agent produced by Derunbao Company) to cool to room temperature. The crankshaft blank is then placed in a tempering furnace, heated to 630°C for 0.5 hours, held for 1.5 hours, removed from the furnace and water-cooled, and then slid into a material box.

[0060] Example 4

[0061] In Example 4, the crankshaft blank used is the crankshaft blank of BYD 1.5T hybrid passenger vehicle, with a single piece weight of 11.8 kg and a processing quantity of 1000 pieces.

[0062] High-temperature tempering treatment of crankshaft blanks: The crankshaft blanks are placed in a mesh belt tempering furnace, heated to 650℃ in 0.5 hours, held at that temperature for 2 hours, and then air-cooled to room temperature after being taken out of the furnace.

[0063] The crankshaft blank after tempering is quenched and tempered: the crankshaft blank, which has been air-cooled to room temperature, is placed into a mesh belt quenching furnace, heated to 840℃ for 20 minutes, held for 100 minutes, cooled to 810℃ for 8 minutes, held for 28 minutes, and then removed from the furnace and slid into a quenching tank (containing water-based quenching agent produced by Derunbao Company) to cool to room temperature. Then the crankshaft blank is placed into a tempering furnace, heated to 620℃ for 20 minutes, held for 80 minutes, removed from the furnace and water-cooled, and then slid into a material box.

[0064] Example 5

[0065] In Example 5, the crankshaft blank used is the crankshaft blank of BYD 1.5T hybrid passenger vehicle, with a single piece weight of 11.8 kg and a processing quantity of 1000 pieces.

[0066] High-temperature tempering treatment of crankshaft blanks: The crankshaft blanks are placed in a mesh belt tempering furnace, heated to 650℃ in 0.5 hours, held at that temperature for 2 hours, and then air-cooled to room temperature after being taken out of the furnace.

[0067] The crankshaft blank after tempering is quenched and tempered: the crankshaft blank, which has been air-cooled to room temperature, is placed into a mesh belt quenching furnace, heated to 860℃ for 40 minutes, held for 80 minutes, cooled to 800℃ for 28 minutes, held for 8 minutes, and then removed from the furnace and slid into a quenching tank (containing water-based quenching agent produced by Derunbao Company) to cool to room temperature. Then the crankshaft blank is placed into a tempering furnace, heated to 640℃ for 40 minutes, held for 100 minutes, removed from the furnace and water-cooled, and then slid into a material box.

[0068] Example 6

[0069] The difference from Example 1 is that the crankshaft blank in Example 6 uses a Hongqi 1.5T passenger car crankshaft blank, with a single piece weight of 13 kg. The remaining parameters and steps are the same as in Example 1.

[0070] Comparative Example 1

[0071] In Comparative Example 1, the crankshaft blank used was the crankshaft blank of BYD 1.5T hybrid passenger vehicle, with a single piece weight of 11.8 kg and a processing quantity of 1000 pieces.

[0072] Normalizing the crankshaft blank: Place the crankshaft blank in a mesh belt normalizing furnace, heat it to 880℃ for 0.5 hours, hold it at that temperature for 1.5 hours, and then air cool it to room temperature.

[0073] The crankshaft blank after normalizing is tempered: the normalized crankshaft blank is placed in a mesh belt quenching furnace, heated to 850℃ for 0.5 hours, held for 1.5 hours, then removed from the furnace and slid into a quenching tank (containing water-based quenching agent produced by Derunbao Company) to cool to room temperature. The crankshaft blank that has cooled to room temperature is placed in a tempering furnace, heated to 630℃ for 0.5 hours, held for 1.5 hours, then removed from the furnace and water-cooled before sliding into a material box.

[0074] Comparative Example 2

[0075] Unlike Comparative Example 1, the crankshaft blank was not normalized; it was directly subjected to quenching and tempering. The remaining parameters and steps were the same as in Comparative Example 1.

[0076] Comparative Example 3

[0077] Unlike Comparative Example 1, the crankshaft blank in Comparative Example 3 uses a crankshaft blank from a Hongqi 1.5T passenger car, with a single piece weight of 13 kg. The remaining parameters and steps are the same as in Comparative Example 1.

[0078] The crankshaft blanks of each embodiment and comparative example after heat treatment were subjected to flaw detection to check for any quenching cracks.

[0079] In Comparative Examples 1 and 3, the crankshaft blanks were heat-treated using a conventional normalizing followed by quenching and tempering process, resulting in a quenching crack rate of 3% or higher. In Comparative Example 2, only a conventional quenching and tempering process was used to heat-treat the crankshaft blanks, and the quenching crack rate was also 3% or higher. Comparison revealed that the quenching crack rate of the sample in Comparative Example 2 was comparable to that of the sample in Comparative Example 1. This indicates that conventional normalizing before quenching and tempering does not effectively reduce the quenching crack rate of the crankshaft blanks after quenching and tempering.

[0080] The proportion of quenching cracks in the crankshaft blanks after heat treatment in Examples 1 to 6 is all below 0.5%. As can be seen from the comparison, by using the method proposed in this invention to first perform high-temperature tempering on the crankshaft blank and then perform quenching and tempering, the risk of quenching cracks in the crankshaft blank during the quenching and tempering process can be significantly reduced, and the loss of scrapped crankshaft blanks can be greatly reduced.

[0081] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," and "some specific embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0082] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method of heat treating a crankshaft blank, characterized by, The material of the crankshaft blank comprises at least one of 42CrMo and 40CrNiMo, and the heat treatment method comprises the following steps: (1) tempering the crankshaft blank: placing the crankshaft blank in a tempering furnace, heating to 620-680℃, heating time 20-40min, holding for 2-3h, removing the crankshaft blank from the furnace, and air cooling to room temperature; (2) quenching and tempering the crankshaft blank after tempering: placing the air-cooled crankshaft blank to room temperature in a quenching furnace, heating to 840-860℃, heating time 20-40min, holding for 80-100min, cooling to 790-810℃, holding for 8-28min, removing from the furnace, placing the crankshaft blank in a quenching tank, cooling to room temperature, placing the crankshaft blank in a tempering furnace, heating to 620-640℃, heating time 20-40min, holding for 80-120min, removing the crankshaft blank from the furnace, and water cooling.

2. The heat treatment method according to claim 1, characterized by, In step (2), the quenching tank contains a quenching agent, and the quenching agent comprises a water-based quenching agent.

3. The heat treatment method according to either one of claims 1 to 2, characterized in that, In step (1), the crankshaft blank is tempered in a mesh belt type tempering furnace. In step (2), the quenching furnace is a mesh belt type quenching furnace.

4. A crankshaft, characterized by The crankshaft is obtained by heat treating a crankshaft blank using the heat treatment method of any one of claims 1-3, and then mechanically processing the heat-treated crankshaft blank.

5. Use of the crankshaft of claim 4 in a vehicle.

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