High-flash-point graded quenching oil and preparation method thereof

Abstract

The invention discloses high-flash-point graded quenching oil and a preparation method thereof, and relates to the technical field of quenching oil. The high-flash-point graded quenching oil comprises base oil and a composite antioxidant, wherein the base oil comprises trimethylolpropane oleate, and the composite antioxidant comprises a phenolic antioxidant, an amine antioxidant, a first antioxidant synergist and a second antioxidant synergist. According to the technical scheme, the high-flash-point oleate is adopted as the base oil, meanwhile, the composite antioxidant is compounded, the provided high-flash-point graded quenching oil has the extremely high flash point, the open flash point can reach 350 DEG C or above, the use temperature can reach 260-280 DEG C, the high-flash-point graded quenching oil is suitable for quenching cooling of high-hardenability workpieces and high-precision workpieces of thin-wall workpieces, and quenching deformation can be reduced. Meanwhile, the high-flash-point graded quenching oil provided by the invention has excellent oxidation resistance and can prevent oil products from being oxidized and aged too early, so that the service life of the oil products is greatly prolonged, and the use cost is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of quenching oils, and particularly relates to a high flash point stepped quenching oil and a preparation method thereof. Background Art

[0002] Heat treatment is an operation process in which metals or alloys are heated, held, and cooled in cooperation to change their internal tissue structures to obtain the required properties. Common heat treatment processes mainly include annealing, normalizing, quenching, and tempering, which are also known as the "four fires" of heat treatment. Among them, quenching is the key process that determines the final properties of the workpiece after heat treatment.

[0003] The quenching cooling process can be divided into three stages. The first stage is the vapor film stage. When the workpiece is immersed in the cooling medium, the medium near the workpiece is rapidly vaporized by heat, forming a continuous vapor film around the workpiece, separating the workpiece from the cooling medium. Heat is transferred through the vapor film by radiation and conduction. The vapor film is a poor conductor of heat, so the cooling rate in this stage is very slow. As the workpiece temperature decreases, the complete vapor film cannot be maintained and breaks, entering the boiling stage. In the boiling stage, the quenching liquid is in direct contact with the workpiece surface and boils. Heat is rapidly transferred from the workpiece by evaporation, so the cooling rate is very fast. Finally, when the workpiece surface temperature drops below the boiling point of the quenching medium, the boiling stage terminates. The third stage is the convection stage. Heat is transferred by convection, and the cooling rate is slower. Quenching of steel is to heat the steel above the critical point (for hypoeutectoid steel, it should be heated 30 - 50°C above the Ac3 temperature; for hypereutectoid steel, it should be heated 30 - 50°C above the Ac1 temperature), and then rapidly cooled to transform the supercooled austenite into martensite. Common quenching processes include direct quenching, martensite stepped quenching, and bainite isothermal quenching, etc. Martensite isothermal stepped quenching is to quench the workpiece from the austenitizing temperature into a quenching medium such as molten salt or stepped oil that is usually maintained just above the Ms point temperature, hold for a period of time to make the temperatures of different cross-sections uniform, and then cool in air, which can significantly reduce deformation.

[0004] The selection of quenching oil needs to be carried out according to the actual situation of the workpiece. Ordinary quenching oil is suitable for small parts with good hardenability; fast quenching oil is suitable for small parts that require a certain hardened layer depth but have poor material permeability; in cases where high hardenability and high cooling capacity are required, especially for the quenching of parts with large cross-sections, super-speed quenching oil is needed; isothermal grading quenching oil is mainly used for thin-walled bearing rings, gears, etc. that require strict control of dimensional changes. At present, the flash point of the grading quenching oil in use on the market is generally between 230 and 300 °C, and the use temperature is between 100 and 160 °C, which can meet the quenching requirements of most workpieces with good hardenability. However, for workpieces with extremely high dimensional accuracy requirements, such as precision parts (automobile gears, high-end tools, etc.) with a tolerance grade of IT6-IT7. Therefore, the existing grading quenching oil products still cannot meet the actual needs, and it is necessary to develop a grading quenching oil with more excellent deformation control. Summary of the Invention

[0005] The main object of the present invention is to propose a high-flash-point grading quenching oil and its preparation method, aiming to solve the problems of low flash point and low use temperature of the existing grading quenching oil.

[0006] To achieve the above object, the present invention proposes a high-flash-point grading quenching oil, which includes a base oil and a compound antioxidant. Among them, the base oil includes trimethylolpropane oleate, and the compound antioxidant includes a phenolic antioxidant, an amine antioxidant, a first antioxidant synergist, and a second antioxidant synergist.

[0007] In an embodiment, the high-flash-point grading quenching oil includes the following components in parts by mass: 89-92 parts of base oil and 8-10 parts of compound antioxidant; Among them, the compound antioxidant includes 1-2 parts of phenolic antioxidant, 4-5 parts of amine antioxidant, 1-2 parts of first antioxidant synergist, and 1-2 parts of second antioxidant synergist.

[0008] In an embodiment, the phenolic antioxidant includes any one of 3,5-di-tert-butyl-4-hydroxyphenol and 2,6-di-tert-butylphenol; and / or, The amine antioxidant includes any one of alkylated diphenylamine and N-phenyl-α-naphthylamine; and / or, The first antioxidant synergist includes any one of benzotriazole and methylbenzotriazole; and / or, The second antioxidant synergist includes any one of dibutylhydroxytoluene and zinc dialkyldithiophosphate.

[0009] In an embodiment, the kinematic viscosity of the base oil at 40 °C is 42-50 mm 2 / s; and / or, The open flash point of the base oil is 330~350°C.

[0010] In one embodiment, the open flash point of the high flash point graded quenching oil is 340~360°C, and the use temperature is 260~280°C.

[0011] The present invention provides a method for preparing the high flash point graded quenching oil as described above, comprising the following steps: Mix the base oil, phenolic antioxidant, amine antioxidant, first antioxidant synergist and second antioxidant synergist to obtain the high flash point graded quenching oil.

[0012] In one embodiment, the step of mixing the base oil, phenolic antioxidant, amine antioxidant, first antioxidant synergist and second antioxidant synergist to obtain the high flash point graded quenching oil comprises: Heat the temperature of the base oil to a first temperature, add the phenolic antioxidant, amine antioxidant, first antioxidant synergist and second antioxidant synergist to the heated base oil, and stir to obtain a mixture; Heat the temperature of the mixture to a second temperature, and perform water treatment to obtain the high flash point graded quenching oil.

[0013] In one embodiment, the first temperature is 50~60°C; and / or, The second temperature is 100~110°C; and / or, The time for the water treatment is 2~3 h.

[0014] The present invention provides an application of the high flash point graded quenching oil as described in the foregoing technical solution in the graded quenching process of metal materials.

[0015] The technical solution of the present invention uses high flash point oleate as the base oil and simultaneously compounded with a composite antioxidant. The provided high flash point graded quenching oil has an extremely high flash point, and the open flash point can reach above 350°C, and the use temperature can reach 260~280°C, which is suitable for the quenching cooling of high-precision workpieces with higher hardenability and thin-walled parts. During the quenching process, since the use temperature of the quenching oil is increased significantly, the temperature difference between the surface and the core of the workpiece is reduced. Therefore, the residual thermal stress and tissue stress of different parts of the workpiece during the quenching process can be reduced, thereby significantly reducing the quenching deformation. At the same time, the high flash point graded quenching oil provided by the present invention has excellent antioxidant performance, which can prevent the oil from oxidizing and aging prematurely, thereby prolonging the service life of the oil and effectively reducing the use cost. Description of the Drawings

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0017] Figure 1 It is a graph of the rotating bomb test results of the high flash point step quenching oil in Embodiment 1 of the present invention; Figure 2 It is a graph of the rotating bomb test results of the high flash point step quenching oil in Embodiment 2 of the present invention.

[0018] The realization of the purpose, functional characteristics and advantages of the present invention will be further described with reference to the embodiments and the drawings. Detailed implementation manners

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0020] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0021] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or the solution where A and B are satisfied simultaneously. In addition, the technical solutions between the embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0022] Common quenching processes include direct quenching, martensitic step quenching, and bainitic isothermal quenching, etc. Martensitic isothermal step quenching is to quench the workpiece from the austenitizing temperature into a quenching medium such as molten salt or step quenching oil that is usually maintained just above the Ms point temperature, hold for a period of time to make the temperatures of different cross-sections uniform, and then air-cool, which can significantly reduce deformation.

[0023] The selection of quenching oil needs to be carried out according to the actual situation of the workpiece. Ordinary quenching oil is suitable for small parts with good hardenability; rapid quenching oil is suitable for small parts that require a certain hardened layer depth but have poor material permeability; in cases where high hardenability and high cooling capacity are required, especially for the quenching of some parts with large cross-sections, super-speed quenching oil is needed; isothermal step quenching oil is mainly used for thin-walled bearing rings, gears, etc. with strict requirements for dimensional changes.

[0024] At present, the flash point of the step quenching oil in use on the market is generally 230 - 300 °C, and the use temperature is 100 - 160 °C, which can meet the quenching of most workpieces with good hardenability. However, for workpieces with extremely high requirements for dimensional accuracy, the existing products obviously cannot meet the actual needs, so it is necessary to develop a step quenching oil with more excellent deformation control.

[0025] Based on the above background, the present invention proposes a high-flash-point step quenching oil, and the high-flash-point step quenching oil includes a base oil and a compound antioxidant; Among them, the base oil includes trimethylolpropane oleate, and the compound antioxidant includes a phenolic antioxidant, an amine antioxidant, a first antioxidant synergist, and a second antioxidant synergist.

[0026] Base oil is the main component of quenching oil, accounting for about 80 - 95% of quenching oil. Therefore, the quality of the base oil is directly related to the quality of quenching oil. Currently, the base oils used for ordinary step quenching oil mainly come from mineral oils and synthetic oils. Mineral oils are divided into Class I, Class II, and Class III, and synthetic base oils are divided into Class IV and Class V. These base oils have relatively low flash points and are difficult to meet the actual requirements. In the technical solution of the present invention, highly refined high - flash - point oleate is used as the base oil. The provided high - flash - point step quenching oil has an extremely high flash point, with an open - cup flash point up to 350 °C, and the use temperature can reach 260 - 280 °C, which can meet the quenching and cooling process requirements of high - hardenability workpieces and high - precision workpieces with thin walls. During the quenching process, since the use temperature of the quenching oil is increased significantly, the temperature difference between the surface and the core of the workpiece is reduced. Therefore, the residual thermal stress and tissue stress in different parts of the workpiece during quenching can be reduced, and thus the quenching deformation can be significantly reduced. At the same time, the present invention uses a compound antioxidant in combination. Phenolic antioxidants and amine antioxidants capture free radicals (ROO·) by providing active hydrogen atoms, interrupting the oxidation chain reaction. And the simultaneous use of phenolic antioxidants and amine antioxidants can produce a synergistic effect, enhancing the overall antioxidant effect; the first antioxidant synergist and the second antioxidant synergist are auxiliary antioxidants, which can decompose hydroperoxides (ROOH) or chelate metal ions to prevent the initiation of oxidation reactions. Therefore, the high - flash - point step quenching oil provided by the present invention has excellent antioxidant properties, can prevent the oil from oxidizing and aging prematurely, thereby extending the service life of the oil and effectively reducing the use cost.

[0027] In an embodiment of the present invention, the high - flash - point step quenching oil comprises the following components in parts by mass: 89 - 92 parts of base oil and 8 - 10 parts of compound antioxidant; Among them, the compound antioxidant comprises 1 - 2 parts of phenolic antioxidant, 4 - 5 parts of amine antioxidant, 1 - 2 parts of the first antioxidant synergist, and 1 - 2 parts of the second antioxidant synergist.

[0028] Trimethylolpropane oleate has a high flash point due to its large molecular weight and poor volatility. However, because it contains unsaturated double bonds and can react with oxygen, it will cause degradation or cross - linking, so its antioxidant property is poor, which easily leads to the gradual deterioration of the oil, and further significantly reduces the cooling performance, failing to meet the requirements of quenching quality. To further improve the antioxidant property of the provided high - flash - point step quenching oil, the present invention uses phenolic antioxidant, amine antioxidant, the first antioxidant synergist, and the second antioxidant synergist in combination. In the technical solution of the present invention, the dosages of phenolic antioxidant, amine antioxidant, the first antioxidant synergist, and the second antioxidant synergist are within the above ranges. The synergistic antioxidant property of the combined use of two types of antioxidants and antioxidant synergists helps to improve the thermal oxidation stability and extend the service life.

[0029] In an embodiment of the present invention, the phenolic antioxidant includes any one of 3,5 - di - tert - butyl - 4 - hydroxyphenol and 2,6 - di - tert - butylphenol. 3,5 - di - tert - butyl - 4 - hydroxyphenol and 2,6 - di - tert - butylphenol have excellent antioxidant properties, good thermal stability, and low volatility. They can maintain activity at relatively high temperatures, are suitable for application scenarios that need to withstand high - temperature environments, and can ensure long - term and stable antioxidant effects. In an embodiment of the present invention, the phenolic antioxidant is 3,5 - di - tert - butyl - 4 - hydroxyphenol.

[0030] In an embodiment of the present invention, the amine antioxidant includes any one of alkylated diphenylamine and N - phenyl - α - naphthylamine. Alkylated diphenylamine and N - phenyl - α - naphthylamine have excellent antioxidant properties and good thermal stability. When used together with phenolic antioxidants, they can produce a synergistic effect and enhance the overall antioxidant effect. In an embodiment of the present invention, the amine antioxidant is alkylated diphenylamine.

[0031] In an embodiment of the present invention, the first antioxidant synergist includes any one of benzotriazole and methylbenzotriazole. In an embodiment of the present invention, benzotriazole is selected as the second antioxidant synergist.

[0032] In an embodiment of the present invention, the second antioxidant synergist includes any one of dibutylhydroxytoluene and zinc dialkyldithiophosphate. In an embodiment of the present invention, dibutylhydroxytoluene is selected as the second antioxidant synergist.

[0033] The technical solution of the present invention uses phenolic antioxidants, amine antioxidants, the first antioxidant synergist, and the second antioxidant synergist simultaneously. Among them, phenolic antioxidants and amine antioxidants are chain - termination antioxidants, which capture free radicals (ROO·) by providing active hydrogen atoms, thereby interrupting the oxidation chain reaction. The first antioxidant synergist and the second antioxidant synergist, as auxiliary antioxidants, can decompose hydroperoxides (ROOH) or chelate metal ions to prevent the initiation of oxidation reactions. By compounding phenolic antioxidants, amine antioxidants, the first antioxidant synergist, and the second antioxidant synergist, the provided high - flash - point graded quenching oil has excellent antioxidant properties.

[0034] In an embodiment of the present invention, the kinematic viscosity of the base oil at 40 °C is 42 - 50 mm 2 / s. The kinematic viscosity affects the fluidity of the quenching oil. A lower viscosity means better fluidity, which can improve the contact efficiency between the quenching oil and the workpiece surface, thereby accelerating the cooling rate; a higher viscosity will slow down the cooling rate. Excessively high viscosity may also cause foam formation and is difficult to eliminate, interfering with the quenching process and reducing the cooling efficiency. Setting the kinematic viscosity of the base oil at 40 °C within the above range helps to balance wettability, cooling requirements, and processability requirements.

[0035] In an embodiment of the present invention, the open flash point of the base oil is 330 - 350 °C. Metalworking fluids are usually composed of a base oil and various functional additives, and the content of the base oil is generally relatively high. Increasing the open flash point of the base oil helps to increase the flash point temperature of the provided high flash point graded quenching oil. The higher the flash point of the quenching oil, the better. In the technical solution of the present invention, the open flash point of the base oil is set to 330 - 350 °C, which is higher than the martensite start temperature MS point of most steels, and can reduce the tissue stress caused by the non-simultaneity of tissue transformation during the quenching and cooling process, thereby reducing the risk of deformation and cracking.

[0036] In an embodiment of the present invention, the open flash point of the high flash point graded quenching oil is 340 - 360 °C, and the use temperature is 260 - 280 °C. During the quenching process, when a high-temperature workpiece enters the oil, it will cause the temperature of the oil to rise. To ensure safety, usually, the use temperature needs to be 60 - 80 °C lower than the open flash point of the quenching oil.

[0037] In an embodiment of the present invention, the water content of the high flash point graded quenching oil is below 300 ppm. When the water content of the quenching oil is relatively high, it will cause the extension and instability of the steam film time of the quenching oil, easily resulting in insufficient hardness of the quenched workpiece, soft spots, workpiece deformation, and even cracking. It will also accelerate the decay of the quenching oil, increase the tendency of the quenching oil to generate sludge and carbon deposits, and shorten the service life of the oil; if the water content in the quenching oil is too high, it will also increase the risk of the quenching oil boiling over, overflowing the tank, and even causing fires. Keeping the water content of the high flash point graded quenching oil below 300 ppm helps to ensure the quality of the quenching process, extend the service life of the oil product, and protect the workpiece from corrosion.

[0038] The present invention provides a method for preparing the high flash point graded quenching oil as described above, comprising the following steps: Mix a base oil, a phenolic antioxidant, an amine antioxidant, a first antioxidant synergist, and a second antioxidant synergist to obtain the high flash point graded quenching oil.

[0039] In an embodiment of the present invention, the step of mixing a base oil, a phenolic antioxidant, an amine antioxidant, a first antioxidant synergist, and a second antioxidant synergist to obtain the high flash point graded quenching oil comprises: Heat the temperature of the base oil to a first temperature, add the phenolic antioxidant, the amine antioxidant, the first antioxidant synergist, and the second antioxidant synergist to the heated base oil, and stir to obtain a mixture; Heat the temperature of the mixture to a second temperature and perform water treatment to obtain the high flash point graded quenching oil.

[0040] In the preparation method of the present invention, the base oil is first heated, and then a phenolic antioxidant, an amine antioxidant, a first antioxidant synergist, and a second antioxidant synergist are added to the base oil. Heating the base oil before adding other raw materials results in a better overall mixing effect of the raw materials.

[0041] In an embodiment of the present invention, the first temperature is 50 - 60°C. Exemplarily, the first temperature can be 50°C, 55°C, or 60°C. Setting the first temperature within the above range helps to improve the solubility, dispersibility, and overall mixing effect of each component, while reducing the influence of air entrainment and moisture, ensuring the quality and performance of the quenching oil.

[0042] In an embodiment of the present invention, the rotation speed during stirring is 400 - 500 rpm, and the stirring time is 2 - 3 h. In an embodiment of the present invention, the rotation speed during stirring is set to 450 rpm, and the stirring time is set to 2 h.

[0043] In an embodiment of the present invention, the second temperature is 100 - 110°C. Exemplarily, the second temperature can be 100°C, 105°C, or 110°C. Setting the second temperature within the above range can make the water content of the high flash point graded quenching oil below 300 ppm.

[0044] In an embodiment of the present invention, the time for water treatment is 2 - 3 h. Setting the time for water treatment within the above range enables the water content of the high flash point graded quenching oil to meet the requirements while controlling the production cost.

[0045] The present invention proposes an application of the high flash point graded quenching oil in the metal material step quenching process.

[0046] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments and the accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0047] In the following embodiments, trimethylolpropane trioleate with an open flash point of 330 - 350°C is purchased from BASF, and the kinematic viscosity at 40°C is 42 - 50 mm 2 / s; Trimethylolpropane trioleate with an open flash point of 280 - 300°C is purchased from Shandong Xinfa Ruijie New Material Technology Co., Ltd.; The 3,5 - di - tert - butyl - 4 - hydroxyphenol is purchased from Qingdao Derunkai Chemical Co., Ltd.; The alkylated diphenylamine is purchased from the South Korean Songwon Group; The benzotriazole is purchased from Tianjin Haoruisen Chemical Co., Ltd.; The dibutylhydroxytoluene is purchased from Tiancheng Chemical (Jiangsu) Co., Ltd.

[0048] Example 1 A high flash point step quenching oil, comprising the following components in parts by mass: 92 parts of trimethylolpropane trioleate (TMPTO, open flash point 343 °C), 4 parts of alkylated diphenylamine, 1 part of 3,5 - di - tert - butyl - 4 - hydroxyphenol, 1 part of benzotriazole, and 2 parts of dibutylhydroxytoluene; The preparation method of the high flash point step quenching oil comprises the following steps: (1) Add trimethylolpropane trioleate to the reaction kettle, heat up to 55 °C, add alkylated diphenylamine, 3,5 - di - tert - butyl - 4 - hydroxyphenol, benzotriazole, and dibutylhydroxytoluene to the heated base oil, and then stir at 450 rpm for 2 h to obtain a mixture; (2) Heat the temperature of the mixture to 105 °C, stir and circulate for 2 h, detect whether the water content is qualified (≤300 ppm). If the water content is too high, continue to stir for water treatment. After the water content is detected to be qualified, the high flash point step quenching oil is obtained.

[0049] Example 2 Compared with Example 1, the difference lies in the raw materials: 90 parts of trimethylolpropane trioleate (TMPTO, open flash point 339 °C), 5 parts of alkylated diphenylamine, 2 parts of 3,5 - di - tert - butyl - 4 - hydroxyphenol, 1.5 parts of benzotriazole, and 1.5 parts of dibutylhydroxytoluene.

[0050] Example 3 Compared with Example 1, the difference lies in that the open flash point of trimethylolpropane trioleate is 341.8 °C.

[0051] Example 4 Compared with Example 1, the difference lies in that the open flash point of trimethylolpropane trioleate is 338.7 °C.

[0052] Comparative Example 1 Compared with Example 1, the difference lies in that the open flash point temperature of trimethylolpropane trioleate is 300 °C.

[0053] Comparative Example 2 Compared with Example 1, the difference lies in that the open flash point temperature of trimethylolpropane trioleate is 280 °C.

[0054] Comparative Example 3 Compared with Example 1, the difference lies in that benzotriazole is not added, and the mass of dibutylhydroxytoluene is 3 parts.

[0055] Comparative Example 4 Compared with Example 1, the difference lies in that dibutylhydroxytoluene is not added, and the mass of benzotriazole is 3 parts.

[0056] Performance Test 1. The basic physical and chemical indexes of the high flash point graded quenching oils of Examples 1-4 and Comparative Examples 1-4 were tested according to the following methods.

[0057] (1) The kinematic viscosity test method was carried out according to Section 5 of the standard test method for the determination of kinematic viscosity and calculation of dynamic viscosity of petroleum products, GB / T 265-1988. The results are shown in Table 1 below.

[0058] (2) The open flash point test method was carried out according to Section 5 of the standard test method for the determination of kinematic viscosity and calculation of dynamic viscosity of petroleum products, GB / T 265-1988. The results are shown in Table 1 below.

[0059] (3) The rotating bomb test method was carried out according to Section 9 of the test method for the determination of oxidation stability of lubricating oils by rotating bomb method, SH / T 0193-2008. The results of the rotating bomb induction period time of Examples 1-4 and Comparative Example 4 (the time corresponding to the pressure dropping 175 kPa from the highest position is the rotating bomb induction period time, and the longer the induction period time, the better the oxidation stability) are shown in Table 1 below. For some test results of the pressure curve and temperature curve of Examples 1-2, please refer to Figure 1 and Figure 2 .

[0060] Table 1 Parameters and performance test results of the high flash point graded quenching oils of Examples 1-4 and Comparative Examples 1-4

[0061] It can be seen from Table 1 that: (1) The open flash points of the high flash point graded quenching oils of Examples 1-4 are between 340 and 360 °C. It can be seen that the quenching oil provided by the present invention is not easy to evaporate and lose, and is environmentally friendly and safe; the open flash points of the high flash point graded quenching oils of Examples 1-4 are higher than those of Comparative Examples 1-2, indicating that the higher the flash point temperature of the base oil, the higher the open flash point of the prepared high flash point graded quenching oil. In addition, by comparing the open flash point results of the base oil and the high flash point graded quenching oil in Examples 1-4, it can be seen that the open flash point of the high flash point graded quenching oil is higher than that of the corresponding base oil, indicating that adding a compound antioxidant to the base oil can help improve the open flash point of the quenching oil.

[0062] (2) The kinematic viscosity at 40 °C of the high flash point graded quenching oils of Examples 1-4 is 46.97-48.82 mm² / s, and the kinematic viscosity at 100 °C is 9.54-9.71 mm² / s.

[0063] (3) Combining Table 1,Figure 1 and Figure 2 The test results of the rotating bomb oxidation test show that the incubation period test results of the rotating bomb of Examples 1-4 are better than those of Comparative Examples 1-2. This indicates that compared with a single antioxidant synergist, when the first antioxidant synergist and the second antioxidant synergist are used simultaneously, the thermal oxidation stability of the high flash point graded quenching oil provided by the present invention is significantly improved. This is because there are no double bonds in the conventional base oil, and a high antioxidant capacity can be achieved by adding a small amount of ordinary antioxidant. However, there are unsaturated double bonds in the base oil TMPTO of the present invention, which are prone to oxidation. Therefore, it is necessary to use a phenolic antioxidant, an amine antioxidant, the first antioxidant synergist and the second antioxidant synergist simultaneously to achieve good thermal oxidation stability and meet the use requirements.

[0064] 2. The cooling performance of the high flash point graded quenching oils of Examples 1-4 and Comparative Examples 1-4 was tested according to the content of Section 7 in the experimental method of nickel alloy probe for measuring the cooling performance of industrial quenching oils specified in JB / T 7951-2004. The test results are shown in Table 2.

[0065] Table 2 Test Results of Cooling Performance of High Flash Point Graded Quenching Oils of Examples 1-4 and Comparative Examples 1-4

[0066] As can be seen from Table 2, the high flash point graded quenching oils of Examples 1-4 all have good cooling performance, and the maximum cooling rate is 89.6 °C / s.

[0067] The above are only exemplary embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A high flash point marquenching oil, characterized in that, The high flash point step quenching oil comprises a base oil and a compound antioxidant; Among them, the base oil comprises trimethylolpropane oleate, and the compound antioxidant comprises a phenolic antioxidant, an amine antioxidant, a first antioxidant synergist and a second antioxidant synergist.

2. The high flash point marquenching oil according to claim 1, characterized in that, The high flash point step quenching oil comprises the following components in parts by mass: 90-92 parts of base oil and 8-10 parts of compound antioxidant; Among them, the compound antioxidant comprises 1-2 parts of phenolic antioxidant, 4-5 parts of amine antioxidant, 1-2 parts of first antioxidant synergist and 1-2 parts of second antioxidant synergist.

3. The high flash point martempering oil according to claim 2, characterized in that, The phenolic antioxidant comprises any one of 3,5-di-tert-butyl-4-hydroxyphenol and 2,6-di-tert-butylphenol; and / or, The amine antioxidant comprises any one of alkylated diphenylamine and N-phenyl-α-naphthylamine; and / or, The first antioxidant synergist comprises any one of benzotriazole and methylbenzotriazole; and / or, The second antioxidant synergist comprises any one of dibutylhydroxytoluene and zinc dialkyldithiophosphate.

4. The high flash point marquenching oil according to claim 1, characterized in that, The kinematic viscosity of the base oil at 40 °C is 42 to 50 mm 2 / s; and / or, The open flash point of the base oil is 330-350 °C.

5. The high flash point step quenching oil according to claim 1, wherein The open flash point of the high flash point step quenching oil is 340-360 °C, and the use temperature is 260-280 °C.

6. A preparation method of a high flash point graded quenching oil as described in any one of claims 1 to 5, characterized in that, Comprising the following steps: Mix the base oil, phenolic antioxidant, amine antioxidant, first antioxidant synergist and second antioxidant synergist to obtain the high flash point step quenching oil.

7. The preparation method of the high flash point marquenching oil according to claim 6, characterized in that, The step of mixing the base oil, phenolic antioxidant, amine antioxidant, first antioxidant synergist and second antioxidant synergist to obtain the high flash point step quenching oil comprises: Heat the temperature of the base oil to a first temperature, add the phenolic antioxidant, amine antioxidant, first antioxidant synergist and second antioxidant synergist to the heated base oil, and stir to obtain a mixture; Heat the temperature of the mixture to a second temperature, and perform water treatment to obtain the high flash point step quenching oil.

8. The preparation method of the high flash point marquenching oil according to claim 7, characterized in that, The first temperature is 50-60 °C; and / or, The second temperature is 100-110 °C; and / or, The time for water treatment is 2-3 h.

9. Application of a high flash point step quenching oil according to any one of claims 1 to 5 in a step quenching process of metal materials.

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