Carburizing and quenching heat treatment process for new energy automobile parts

Abstract

The invention relates to the field of surface treatment processes of new energy automobile parts, in particular to a carburizing and quenching heat treatment process of the new energy automobile parts. The method comprises the following steps that S1, a plurality of blanks are sequentially subjected to feeding inspection, loading and pre-cleaning, and a sample A is obtained; s2, the sample A is subjected to carburizing treatment, and a sample B is obtained; s3, the sample B is subjected to oil cooling treatment, the oil temperature is 100-130 DEG C, the stirring speed of oil is 200-300 r / min, then post-cleaning is conducted, and a sample C is obtained; and S4, the sample C is subjected to tempering treatment, and the new energy automobile part is obtained. The temperature in the tempering treatment process is higher than that in the oil cooling treatment process. By means of the process, high product consistency can be obtained under batch production, so that the requirements of new energy automobile accessories for high precision and high stability are met.

Description

Technical Field

[0001] The present application relates to the field of surface treatment technology for new energy automobile accessories, and more specifically, it relates to a carburizing and quenching heat treatment process for new energy automobile accessories. Background Art

[0002] The heat treatment technology of new energy vehicle accessories occupies an important position in the modern manufacturing industry, and it mainly focuses on the carburizing and quenching process. This process can significantly improve the hardness and wear resistance of the metal material surface, meeting the demand for high-performance parts of new energy vehicles. With the rapid development of the new energy vehicle industry, the performance requirements for automotive accessories are increasing. Heat treatment technology, as a key link, directly affects the quality and life of the product. Although the traditional heat treatment process can basically meet general industrial needs, in the manufacturing of new energy vehicle accessories, how to balance the surface hardness and core toughness while ensuring the stability of mass production has become a technical problem that needs to be solved urgently.

[0003] In the prior art, in order to achieve effective heat treatment of new energy vehicle parts, the following conventional methods are usually used: first, the parts are placed in a high temperature environment for a single stage of carburizing treatment, followed by rapid cooling to form a martensitic structure; second, the diffusion depth of carbon atoms is controlled by adjusting the carburizing temperature and time. Although the prior art methods have achieved certain results in improving the performance of parts, there are still significant limitations.

[0004] Especially in mass production scenarios, the defects of traditional processes have become increasingly prominent: on the one hand, it is difficult to ensure the uniformity of part thickness, and the depth of the carburized layer at different positions varies greatly from the quenching cooling rate, resulting in significant fluctuations in material properties (such as hardness and toughness) and poor product consistency, which makes it difficult to meet the high-precision and high-stability requirements of new energy vehicle accessories; on the other hand, when the existing quenching process uses high-temperature carburizing of more than 900°C and low-temperature carburizing of 60°C or below, the material is forced to undergo a slow cooling process, which not only greatly prolongs the production cycle and increases energy consumption, but also easily leads to uneven cooling rates, resulting in abnormal residual stress distribution, further aggravating the problems of part deformation, crack tendency and hardness gradient, which ultimately manifests as a low pass rate in mass production. Summary of the invention

[0005] This application improves product consistency under mass production, meets the requirements of new energy vehicle accessories for high precision and high stability, and provides a carburizing and quenching heat treatment process for new energy vehicle accessories.

[0006] The present application provides a carburizing and quenching heat treatment process for new energy vehicle accessories, which is obtained by the following method: S1: Perform feed inspection, loading, and pre-cleaning on a number of blanks in sequence to obtain sample A; S2: The sample A is carburized at a temperature of 760 - 880 °C to obtain sample B; S3: The sample B is oil-cooled at an oil temperature of 100 - 130 °C and an oil stirring rate of 200 - 300 r / min, and then post-cleaned to obtain sample C; S4: The sample C is tempered to obtain new energy vehicle parts; The carburizing process is sequentially provided with three stages a, b, and c. Sorted by temperature, b > c > a; sorted by time, b > a > c; the absolute value of the temperature difference between the three stages of a, b, and c is ≤ 120 °C, and the absolute value of the time difference between the three stages of a, b, and c is ≤ 180 min; the temperature during the tempering process is higher than the temperature of the oil cooling treatment.

[0007] By adopting the above technical solution, the carburizing process is divided into three stages a, b, and c. Among them, the temperature of stage b is the highest and the time is the longest, effectively promoting the rapid diffusion of carbon atoms to the surface to form a high-hardness martensite structure, significantly improving the surface hardness.

[0008] The temperature of stage c is in the middle, further optimizing the carbon concentration distribution, ensuring uniform hardness in the transition zone, and avoiding carbide aggregation. As a low-temperature stage, stage a extends the holding time, making the diffusion of carbon atoms into the core more uniform, thus ensuring sufficient toughness in the core. The oil cooling treatment uses isothermal quenching oil at 100 - 130 °C and is combined with a stirring rate of 200 - 300 r / min to achieve uniform cooling, avoiding local overheating or deformation; and for the carburizing process, the temperature is 760 - 880 °C, and the oil cooling treatment uses 100 - 130 °C. At this temperature ratio, a series of quality problems caused by excessive temperature can be avoided.

[0009] The tempering temperature is higher than the oil cooling temperature, further stabilizing the tissue properties, reducing internal stress, and ensuring the overall hardness uniformity. The temperature difference between each stage is controlled within 120 °C, and the time difference is controlled within 180 minutes. The process parameters are strictly matched, significantly improving the process repeatability and stability. In summary, through the synergistic effect of staged carburizing, precise cooling, and stable tempering, the process of this application can not only carry out mass production, but also obtain new energy vehicle parts with excellent quality, uniform hardness, and stable performance.

[0010] Preferably, the tempering treatment is denoted as e. Sorted by temperature, b > c > e > a; sorted by time, b > e > a > c.

[0011] By adopting the above technical solution, the tempering treatment temperature e is lower than the temperatures in the b and c stages of the carburizing treatment, but higher than the temperature in the a stage, ensuring the effective relief of stress while avoiding excessive softening. In terms of time, the tempering treatment time e is longer than those in the a and c stages, but shorter than that in the b stage, guaranteeing the sufficiency of the microstructure transformation, enhancing the overall toughness of the material, reducing the risk of brittle fracture, and thus significantly improving the mechanical properties and service life of the workpiece.

[0012] Preferably, the a stage of the carburizing treatment is an isothermal pre-treatment stage.

[0013] By adopting the above technical solution, the a stage of the carburizing treatment being an isothermal pre-treatment stage can ensure the temperature uniformity of the blank in this stage and avoid uneven carbon concentration caused by temperature fluctuations. This isothermal treatment method helps the stable diffusion of carbon atoms in the metal matrix, laying a foundation for the subsequent b and c stages of the carburizing treatment, and thus enhancing the uniformity and quality stability of the overall carburized layer.

[0014] Preferably, the b stage of the carburizing treatment is divided into three stages: temperature equalization, strong carburization, and diffusion, denoted as b1 > b2 > b3 respectively; in terms of time from high to low, b2 > b3 > a > c > b1.

[0015] By adopting the above technical solution, the b stage of the carburizing treatment being divided into three sub-stages of temperature equalization, strong carburization, and diffusion respectively optimizes the temperature and time parameters, significantly enhancing the performance of new energy vehicle parts. The specific effects are as follows: The temperature equalization stage (b1) ensures uniform temperature distribution inside the blank, reduces thermal stress, and lays a foundation for the subsequent carburizing process.

[0016] The strong carburization stage (b2) promotes the rapid diffusion of carbon atoms to the metal surface by extending the holding time, forming a high-carbon concentration layer and effectively enhancing the surface hardness.

[0017] The diffusion stage (b3) further optimizes the distribution of carbon atoms, enabling the carbon concentration to gradually transition from the surface to the core, and avoiding brittleness problems caused by excessive carbon concentration.

[0018] By reasonably allocating the time ratios of b1, b2, and b3 and combining with the control of overall process parameters, the optimization of the hardness gradient is achieved, while ensuring the stability and repeatability of the overall process.

[0019] Preferably, the c stage is quenching, and in terms of carbon potential ranking, b2 > b3 > c.

[0020] By adopting the above technical solution, the c stage, as the quenching stage, cooperates with the strong carburizing and diffusion stages in the b stage to ensure that the carbon potential gradually decreases from b2 to b3 and then to c. This design effectively controls the distribution of carbon atoms, forming a high-hardness layer on the surface while avoiding excessive carbon concentration in the core, which may lead to increased brittleness. Specifically, the carbon potential in the c stage is lower than that in the b3 stage, which can prevent overheating in the core or excessive precipitation of carbides during the quenching process, thereby improving the overall toughness and hardness uniformity of the workpiece.

[0021] Preferably, the carbon potential in the c stage is ≧0.8% C, and the carbon potential in the b2 stage is ≤1.05% C.

[0022] By adopting the above technical solution, controlling the carbon potential in the c stage not to be lower than 0.8% C ensures that the carbon concentration is maintained at an appropriate level during the quenching process, avoiding the problem of insufficient hardness in the quenched layer due to too low carbon potential. At the same time, restricting the carbon potential in the b2 stage to not exceed 1.05% C effectively prevents the increase in surface brittleness and carbide aggregation of the workpiece caused by too high carbon concentration, thereby optimizing the organizational structure of the carburized layer and improving the comprehensive mechanical properties of the workpiece.

[0023] Preferably, the oil cooling treatment uses isothermal quenching oil.

[0024] By adopting the above technical solution, using isothermal quenching oil for oil cooling treatment can achieve a uniform and stable cooling effect. Specifically, the use of isothermal quenching oil avoids the problems of deformation and inconsistent hardness caused by uneven cooling speed in the traditional quenching process, improves the dimensional stability of the workpiece after quenching, reduces the internal stress generated during the quenching process, and lowers the risk of workpiece cracking. This optimization significantly improves the quenching quality of new energy vehicle parts, ensuring the consistency and reliability of products in mass production.

[0025] Preferably, the kinematic viscosity of the isothermal quenching oil at 40°C is 62 - 67 mm / s.

[0026] By adopting the above technical solution, precisely controlling the kinematic viscosity of the isothermal quenching oil within the range of 62 - 67 mm / s at 40°C can achieve the following effects: The precise control of the viscosity range ensures the stability of the cooling speed during the quenching process, avoiding the problems of insufficient cooling due to too high viscosity or too fast cooling caused by too low viscosity, thereby improving the hardness uniformity of the quenched workpiece; The appropriate viscosity range helps to form a stable oil film, reducing the microscopic stress concentration on the workpiece surface and further improving the surface quality and toughness of the workpiece.

[0027] Preferably, the oil used in the oil cooling treatment consists of isothermal quenching oil and a dispersion stabilizer, and the dosage of the dispersion stabilizer accounts for ≤3.2 wt% of the dosage of the isothermal quenching oil.

[0028] By adopting the above technical solution, the isothermal quenching oil with a dispersion stabilizer added during oil cooling treatment can significantly improve the cooling performance and process stability. The specific effects include: controlling the addition amount of the dispersion stabilizer within a reasonable range (≤3.2 wt%), effectively preventing the sedimentation of additives, and improving the physical dispersion of the quenching oil; at the same time, delaying the aging of the oil product and extending the service life; optimizing the oil film performance, achieving a balance between lubrication and cooling, and avoiding deformation caused by overheating on the workpiece surface or too fast cooling rate, thereby improving the hardness uniformity and dimensional accuracy of the quenched workpiece.

[0029] Preferably, the dispersion stabilizer is composed of a polymer containing amino and acid groups, a modified polyurea, a branched polyether, and tris(isodecyl) phosphite.

[0030] By adopting the above technical solution, the dispersion stabilizer is composed of a polymer containing amino and acid groups, a modified polyurea, a branched polyether, and tris(isodecyl) phosphite, and their synergistic effect significantly improves the comprehensive performance of the quenching oil. The specific effects include: the polymer containing amino and acid groups forms multiple antioxidant barriers to delay the aging of the oil product; the modified polyurea optimizes the lubrication performance during the cooling process and reduces the surface micro-stress concentration; the branched polyether provides a good steric hindrance effect to prevent the sedimentation of additives and regulate the cooling rate; tris(isodecyl) phosphite enhances the chemical protection performance and extends the service life of the oil product. This multi-component synergistic effect ensures the cooling uniformity and stability of the quenching oil in mass production, thereby significantly improving the hardness consistency and quality reliability of new energy vehicle parts.

[0031] In summary, the present application includes at least one of the following beneficial technical effects: 1. Through the temperature and time gradient distribution in three stages a, b, and c of the carburizing treatment, the diffusion rate and depth of carbon atoms are effectively controlled, achieving a balance between high surface hardness and core toughness, and at the same time avoiding sudden changes in hardness in the transition zone, significantly improving the overall performance consistency; 2. The oil cooling treatment uses an oil temperature of 100 - 130°C and a stirring rate of 200 - 300 r / min to ensure cooling uniformity, avoid local overheating or deformation, and combined with the design that the tempering treatment temperature is higher than the oil cooling temperature, further improves the uniformity of the hardened layer thickness and the overall performance; 3. The dispersion stabilizer is composed of a polymer containing amino and acid groups, a modified polyurea, a branched polyether, and tris(isodecyl) phosphite, and their synergistic effect optimizes the physical dispersion and chemical protection performance of the quenching oil, significantly improving the stability of the quenching process and the quality and qualification rate of new energy vehicle parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the staggered stacking method of the parts in Embodiment 1 of the present application.

[0033] Figure 2 It is a schematic diagram of the carburizing and quenching heat treatment process for a new energy vehicle part in this application. Specific implementation mode

[0034] The following further elaborates on this application in combination with the attached Figure 1-2 drawings and embodiments.

[0035] Partial raw materials: Amino and acid group-containing polymer (polymeric amino and acid group-containing rheology control additive), brand model: Lubrizol SOLTHIX 250; Modified polyurea is a modified polyurea rheology additive, brand model: France First Create -THIX905S: Branched polyether, brand model: German Wacker -908; The brand model of the isothermal quenching oil is Sasol SASO-QUENCH3500. Embodiment

[0036] Embodiment 1 A carburizing and quenching heat treatment process for a new energy vehicle part is obtained by the following method: S1: A number of blanks are successively subjected to incoming inspection, and then 138 qualified parts are stacked in a loading device with multiple layers of racks, and the blanks on adjacent layers of racks are placed staggeredly. Referring to Figure 1 the stacking method, after loading is completed, the loading device with blanks is placed in a vacuum cleaning machine with a power of 81KW and completely immersed, and pre-cleaning is carried out for 10 minutes to obtain sample A; S2: Sample A (with the loading device) is placed in a carburizing furnace for carburizing treatment. The carburizing treatment is successively provided with three stages a, b, and c. Among them, stage a is an isothermal pretreatment stage, the temperature is 760°C, and the isothermal time is 60 minutes; then it is heated to 880°C for stage b treatment. Stage b is divided into three stages: equalizing temperature, strong carburizing, and diffusion, which are respectively denoted as b1>b2>b3. Specifically, the time for equalizing temperature (b1) in stage b is 10 minutes; then it enters the strong carburizing (b2) stage. For example, ethanol is introduced into the carburizing furnace to form a carburizing atmosphere, the ethanol flux is 4.3L / h, and its carbon potential is 1.05% C, and the time is 150 minutes; then it enters the diffusion (b3) stage, and its carbon potential is 0.85% C, and the time is 50 minutes; finally, it enters stage c (quenching), and its carbon potential is 0.80% C, and the time is 30 minutes to obtain sample B; S3: Perform oil cooling treatment on Sample B (with a loading device). Isothermal quenching oil is used for the oil cooling treatment, the oil temperature is 110 °C, the stirring rate of the oil is 300 r / min, and then post-cleaning is carried out. The post-cleaning is carried out in a vacuum cleaning machine with a power of 81 KW, completely immersing it, and pre-cleaning is carried out for 10 min to obtain Sample C; S4: Perform tempering treatment on Sample C (with a loading device), the tempering temperature is 165 °C, the time is 180 min, and then place it in the air and cool it to room temperature at normal temperature to obtain new energy vehicle parts.

[0037] The above specific carburizing and quenching heat treatment process refers to Figure 2 。

[0038] Among them, sorted by temperature, b > c > a; sorted by time, b > a > c; the absolute value of the temperature difference between a and b is equal to 120 °C, the absolute value of the temperature difference between b and c is equal to 50 °C, the absolute value of the temperature difference between a and b is equal to 150 min, and the absolute value of the temperature difference between b and c is equal to 180 min; the temperature during the tempering treatment is higher than the temperature of the oil cooling treatment.

[0039] If. The tempering treatment is denoted as e, sorted by temperature, b > c > e > a, sorted by time, b > e > a > c.

[0040] Sorted by carbon potential, b2 > b3 > c. The kinematic viscosity of the isothermal quenching oil at 40 °C is 62 - 67 mm / s.

[0041] The blank material is 20CrMnTiH (carburizing steel). In addition, the heating and cooling rates in this embodiment are both 10 °C / min.

[0042] Example 2 The difference between Example 2 and Example 1 lies in the different oil cooling treatment processes. Specifically, the oil temperature is 100 °C and the stirring rate of the oil is 300 r / min.

[0043] Example 3 The difference between Example 3 and Example 1 lies in the different oil cooling treatment processes. Specifically, the oil temperature is 120 °C and the stirring rate of the oil is 200 r / min.

[0044] Example 4 The difference between Example 4 and Example 1 is that: the oil used in the oil cooling treatment consists of isothermal quenching oil and a dispersion stabilizer, and the value of the amount of the dispersion stabilizer accounting for the amount of the isothermal quenching oil ≤ 3.2 wt%. The dispersion stabilizer is composed of a polymer containing amino and acid groups, modified polyurea, branched polyether, and trisoisodecyl phosphite in a weight ratio of 1:1:1:0.2.

[0045] Example 5 Example 5 is different from Example 4 in that the dispersion stabilizer is composed of a polymer containing amino groups and acid groups and a modified polyurea in a weight ratio of 1:1.

[0046] Example 6 Example 6 is different from Example 4 in that the dispersion stabilizer is composed of a branched polyether and tris(isodecyl) phosphite in a weight ratio of 2:1.

[0047] Example 7 Example 7 is different from Example 4 in that the dispersion stabilizer is a polymer containing amino groups and acid groups.

[0048] Example 8 Example 8 is different from Example 4 in that the polymer containing amino groups and acid groups is replaced with an equal amount of modified polyurea.

[0049] Example 9 Example 9 is different from Example 4 in that the branched polyether is replaced with an equal amount of modified polyurea.

[0050] Comparative Example Comparative Example 1 Comparative Example 1 is different from Example 1 in that, in the order of temperature, a > b = c, specifically, the temperature of a is 880 °C, and the temperatures of b and c are 850 °C.

[0051] Comparative Example 2 Comparative Example 2 is different from Example 1 in that the temperature in the b stage is 920 °C.

[0052] Comparative Example 3 Comparative Example 3 is different from Example 1 in that, in the order of time, b > c > a, specifically, the time of b remains unchanged, the time of a is 30 min, and the time of c is 60 min.

[0053] Comparative Example 4 Comparative Example 4 is different from Example 1 in that the oil temperature is 60 °C.

[0054] Comparative Example 5 Comparative Example 5 is different from Example 1 in that the stirring rate is 30 r / min.

[0055] Performance Detection Test Detection Method / Test Method The inner diameter of the bearing in this application is 70 mm, the outer diameter is 140 mm, the height is 35 mm, the stacking method is staggered stacking, the spacing between adjacent blanks is 2 cm, the spacing between the upper and lower layers is 5 cm, and the arrangement reference Figure 1 .

[0056] Test 1 1. Crystal item - physical property - appearance pass rate: Referring to the national standard GB / T 13298 - 2015, use a metallurgical microscope to observe the surfaces of all the fittings obtained in Examples 1 - 9 and Comparative Examples 1 - 5, and evaluate the crystal item structure: carbide ≤ grade 4; the core structure (martensite, bainite, and acicular ferrite), martensite, and retained austenite are all ≤ grade 4, which is qualified; refer to GB / T 9450 2005 for detecting that the thickness of the sample surface is 0.5 - 0.8 mm / 550HV1 is qualified; the surface hardness is within the range of 59 - 63 HRC, which is qualified, and the core hardness is within the range of 30 - 45 HRC is qualified; observe whether there are contaminants, cracks, spots, etc. on the surface of each sample. If there is no such situation, it is recorded as qualified, otherwise it is unqualified, and calculate the pass rate.

[0057] 2. Thickness uniformity of the hardened layer: Use the above - mentioned thickness - testing method to test the thickness of the hardened layer on the outer surface. Take 3 test points along the circumferential direction of the bearing respectively, and the distance between adjacent test points is greater than 20 mm. Test the thickness of the hardened layer at the three points, and calculate the difference between the test point with the maximum thickness and the test point with the minimum thickness. When the difference is equal to or greater than 0.3 mm, it is recorded as unqualified. When the difference is less than 0.3 mm, it is recorded as qualified; then count the number of A - grades. The more the number of A - grades, the higher the thickness uniformity of the sample surface. After mass production, the higher the quality, and calculate the pass rate.

[0058] Test 2 In Examples 1 - 9 and Comparative Examples 1 - 5, a loading device that can hold 276 qualified blank parts is used, and the distance between adjacent blank parts is 1 cm, and the distance between upper and lower layers is 3 cm. All the obtained fittings are then tested in Test 1 above to obtain the corresponding pass rates.

[0059] The specific experimental data are shown in Table 1; Table 1 Experimental data of Examples 1 - 9 and Comparative Examples 1 - 4 Combining Example 1 and Comparative Examples 1 - 3 and referring to Table 1, it can be seen that the pass rates of Comparative Examples 1 - 3 are all less than that of Example 1, and the probability of defective products increases with the increase in the batch quantity. It shows that in the quenching treatment of this application, for the temperature and time in stages a, b, and c, sorted by temperature, b > c > a; sorted by time, b > a > c, and the highest is below 900 °C. Coupled with the oil - cooling process and parameters of this application, the quality of the final fittings is better.

[0060] Comparing Comparative Example 1 with Comparative Examples 4-5 and combining with Table 1, it can be seen that the qualified rates of Comparative Examples 1-3 are all lower than that of Example 1, and the probability of defective products increases with the increase in the batch quantity. This shows that by using the oil cooling process of the present application, with an oil temperature of 100-130°C and a stirring rate of 200-300 r / min, the cooling uniformity is ensured, avoiding local overheating or deformation. Combining with the design that the tempering treatment temperature is higher than the oil cooling temperature, the uniformity of the hardened layer thickness and the overall performance are further improved.

[0061] Comparing Example 1, Examples 5-9 with Example 4, the qualified rates of Example 1, Examples 5-9 are all lower than that of Example 4, and with the increase in the number of fittings, the probability of unqualified samples in Example 1, Examples 5-9 increases. Furthermore, it shows that the dispersion stabilizer obtained by compounding a high molecular polymer containing amino and acid groups, modified polyurea, branched polyether, and trisoisodecyl phosphite plays a better dispersion and stabilization role, further reducing the defective rate of the product and the quality of the fittings after mass production.

[0062] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A carburizing and quenching heat treatment process for new energy vehicle parts, characterized in that, Obtained by the following method: S1: Feed several embryo parts for inspection, loading, and pre-cleaning in sequence to obtain sample A; S2: Perform carburizing treatment on sample A at a temperature of 760 - 880 °C to obtain sample B; S3: Perform oil quenching treatment on sample B with the oil temperature at 100 - 130 °C and the stirring rate of the oil at 200 - 300 r / min, and then perform post-cleaning to obtain sample C; S4: Perform tempering treatment on sample C to obtain new energy vehicle parts; The carburizing treatment is sequentially provided with three stages a, b, and c. Sorted by temperature, b > c > a; sorted by time, b > a > c; the absolute value of the temperature difference between the three stages of a, b, and c ≤ 120 °C, and the absolute value of the temperature difference between the three stages of a, b, and c ≤ 180 min; the temperature during the tempering treatment process is higher than the temperature of the oil quenching treatment.

2. The carburizing and quenching heat treatment process for a new energy vehicle accessory according to claim 1, characterized in that: The tempering treatment is denoted as e. Sorted by temperature, b > c > e > a, and sorted by time, b > e > a > c.

3. The carburizing and quenching heat treatment process for a new energy vehicle accessory according to claim 1, characterized in that: Stage a of the carburizing treatment is an isothermal pretreatment stage.

4. The carburizing and quenching heat treatment process for a new energy vehicle accessory according to claim 1, characterized in that: Stage b of the carburizing treatment is divided into three stages: equalizing temperature, intensive carburizing, and diffusion, denoted as b1 > b2 > b3 respectively; sorted by time from high to low, b2 > b3 > a > c > b1.

5. The carburizing and quenching heat treatment process for a new energy vehicle accessory according to claim 4, characterized in that: Stage c is quenching. Sorted by carbon potential, b2 > b3 > c.

6. The carburizing and quenching heat treatment process for a new energy vehicle accessory according to claim 5, characterized in that: The carbon potential of stage c ≥ 0.8% C, and the carbon potential of stage b2 ≤ 1.05% C.

7. The carburizing and quenching heat treatment process for a new energy vehicle accessory according to claim 1, characterized in that: Isothermal quenching oil is used for the oil quenching treatment.

8. The carburizing and quenching heat treatment process for a new energy vehicle accessory according to claim 7, characterized in that: The kinematic viscosity of the isothermal quenching oil at 40 °C is 62 - 67 mm / s.

9. The carburizing and quenching heat treatment process for a new energy vehicle accessory according to claim 1, characterized in that: The oil used in the oil quenching treatment is composed of isothermal quenching oil and a dispersion stabilizer, and the dosage of the dispersion stabilizer accounts for ≤ 3.2 wt% of the dosage of the isothermal quenching oil.

10. The carburizing and quenching heat treatment process for a new energy vehicle accessory according to claim 9, characterized in that: The dispersion stabilizer is composed of a polymer containing amino and acid groups, modified polyurea, branched polyether, and tris(isodecyl) phosphite.

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