A method for isothermal quenching of austempered ductile iron (ADI) castings

Abstract

The application relates to the technical field of isothermal quenching, and proposes an austempering method for prolonging the service life of ADI castings, which comprises the following steps: collecting the thickness and surface area of a casting to be isothermally quenched, preheating the casting, performing first heat preservation treatment, heating the casting to austenitizing temperature, performing second heat preservation treatment, collecting heat flow and the temperature of the casting during isothermal quenching of the casting, marking a target collection time and a prediction basis time, determining a quenching heat release influence coefficient of the target collection time and a prediction weight, combining the temperature of the casting to obtain a casting temperature prediction value of a next adjacent collection time of the target collection time, performing temperature compensation on the isothermal quenching of the casting according to the casting temperature prediction value, performing air cooling operation and cleaning on the casting after the isothermal quenching is completed, and completing the isothermal quenching of the austempered ductile iron. The application can guarantee the smooth progress of the temperature compensation process of the isothermal quenching.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of isothermal quenching, in particular to an austempered ductile iron isothermal quenching method for prolonging the service life of ADI castings. BACKGROUND

[0002] ADI is austempered ductile iron, that is, austempered ductile iron. Austempered ductile iron is quenched isothermally, that is, through a heat treatment process, cheap ductile iron is formed into an austenite structure and excellent strength and toughness are obtained. In the process of preparing austempered ductile iron using the isothermal quenching technology, high-precision temperature sensors such as thermocouples and infrared thermometers are usually used to monitor the temperature data in real time to ensure the casting precision of the process. When the casting after preheating is transferred to an isothermal quenching medium such as a molten salt bath or a metal bath, a large temperature change usually occurs, that is, the quenching medium is quickly cooled after stirring. Generally, the temperature of the quenching medium is compensated by simulating the temperature field or the historical temperature change curve.

[0003] However, isothermal quenching is a heat release process. The longer the isothermal quenching time is, the higher the ambient temperature around the casting is. This will change the heat passing through the surface of the casting within the same quenching time, thereby causing a deviation between the simulated casting temperature and the real casting temperature in the temperature compensation process, affecting the stability of the heating temperature of the casting, and easily leading to cracks and damage to the toughness of the prepared ADI casting. SUMMARY

[0004] The application provides an austempered ductile iron isothermal quenching method for prolonging the service life of ADI castings to solve the problem that the simulated temperature of the casting is different from the real temperature in the temperature compensation process of isothermal quenching, thereby causing the performance and quality of the prepared ADI casting to be substandard. The technical scheme adopted is as follows:

[0005] One embodiment of the application provides an austempered ductile iron isothermal quenching method for prolonging the service life of ADI castings, which comprises the following steps:

[0006] The thickness and surface area of the casting to be isothermally quenched are collected and measured, the casting is sequentially subjected to preheating treatment, first heat preservation treatment, heating to austenitizing temperature treatment and second heat preservation treatment, the treated casting is transferred to a quenching medium, the casting is isothermally quenched, and the heat flow and the casting temperature of the casting at different collection times are collected in the isothermal quenching process;

[0007] Any one collection time is recorded as a target collection time, the quenching heat release influence coefficient of each target collection time is determined respectively according to the thickness and surface area of the casting, the heat flow of each collection time and the time length of quenching that has been carried out, the prediction weight of the target collection time is determined according to the difference between the quenching heat release influence coefficients of different collection times adjacent to the target collection time, the casting temperature prediction value of the next adjacent collection time of the target collection time is obtained in combination with the casting temperatures of the target collection time and different collection times adjacent to the target collection time;

[0008] The isothermal quenching of the casting is compensated according to the casting temperature prediction value, the air cooling operation and cleaning are carried out on the casting that has completed the isothermal quenching, and the isothermal quenching of the austempered ductile iron is completed.

[0009] Further, the holding time of the first holding treatment and the second holding treatment of the casting is:

[0010] The holding time of each millimeter thickness of the casting is 2 minutes.

[0011] Further, the austenitizing temperature in the austenitizing temperature treatment process should be:

[0012] Greater than or equal to 850 DEG C and less than or equal to 950 DEG C.

[0013] Further, the specific method of determining the quenching heat release influence coefficient of each target collection time according to the thickness and surface area of the casting, the heat flow of each collection time and the time length of quenching that has been carried out includes:

[0014] The heat conduction coefficient of the target collection time is calculated according to the thickness and surface area of the casting and the heat flow of the target collection time.

[0015] The quenching heat release influence coefficient of the target collection time is determined according to the difference between the heat conduction coefficients of the first collection time and the target collection time for the isothermal quenching of the casting, the thickness of the casting and the time length of quenching of the casting at the target collection time.

[0016] Further, the specific method of determining the quenching heat release influence coefficient of the target collection time according to the difference between the heat conduction coefficients of the first collection time and the target collection time for the isothermal quenching of the casting, the thickness of the casting and the time length of quenching of the casting at the target collection time includes:

[0017] The first difference value of the target collection time is recorded as the difference value between the heat conduction coefficient of the target collection time and the heat conduction coefficient of the first collection time for the isothermal quenching of the casting.

[0018] The first ratio value of the target collection time is recorded as the ratio value between the thickness of the casting and the time length of quenching of the casting at the target collection time.

[0019] The first difference value of the target acquisition time is recorded as the quenching heat release influence coefficient of the target acquisition time.

[0020] Further, the method for determining the prediction weight of the target acquisition time according to the difference between the quenching heat release influence coefficients of the adjacent acquisition times adjacent to the target acquisition time comprises the following specific method:

[0021] The first preset number of acquisition times adjacent to the target acquisition time are recorded as the prediction basis time of the target acquisition time.

[0022] The second ratio of the target acquisition time is determined according to the quenching heat release influence coefficient of the prediction basis time of the target acquisition time and the target acquisition time.

[0023] The ratio of the number 2 to the time interval of the adjacent acquisition time is recorded as the third ratio of the target acquisition time.

[0024] The positive correlation processing result of the second ratio and the third ratio of the target acquisition time is recorded as the prediction weight of the target acquisition time.

[0025] Further, the method for determining the second ratio of the target acquisition time according to the quenching heat release influence coefficient of the prediction basis time of the target acquisition time and the target acquisition time comprises the following specific method:

[0026] The sum of the quenching heat release influence coefficient of the target acquisition time and the quenching heat release influence coefficient of the prediction basis time of the target acquisition time is recorded as the total quenching heat release influence coefficient of the target acquisition time, and the ratio of the quenching heat release influence coefficient of the target acquisition time to the total quenching heat release influence coefficient is recorded as the second ratio of the target acquisition time.

[0027] Further, the method for obtaining the casting temperature prediction value of the next adjacent acquisition time of the target acquisition time comprises:

[0028] The prediction weight of the target acquisition time is taken as the value of the smoothing coefficient, and the data prediction is performed according to the casting temperature of the target acquisition time and all prediction basis times of the target acquisition time, so as to obtain the casting temperature prediction value of the next adjacent acquisition time of the target acquisition time.

[0029] Further, the method for performing temperature compensation on the isothermal quenching of the casting according to the casting temperature prediction value comprises the following specific method:

[0030] The casting temperature prediction value of the next adjacent acquisition time of the target acquisition time is taken as the casting temperature of the next adjacent acquisition time of the target acquisition time, so that the component temperature of the isothermal quenching of the casting can maintain the preset target temperature, and the temperature compensation of the isothermal quenching process can be realized.

[0031] Further, the air cooling operation and cleaning of the castings completed isothermal quenching includes the specific method:

[0032] Air cooling the casting temperature to room temperature, and removing the residual quenching medium of the casting.

[0033] The beneficial effects of the present application are:

[0034] In the process of isothermal quenching of the casting, the present application evaluates the influence of quenching heat release at each collection time on the casting, obtains the quenching heat release influence coefficient of the target collection time, determines the prediction weight of the target collection time according to the difference between the quenching heat release influence coefficients of the different collection times adjacent to the target collection time, and determines the different collection times adjacent to the target collection time and the contribution degree of the casting temperature of the target collection time to the casting temperature prediction value of the next adjacent collection time of the target collection time, and at the same time, determines the casting temperature prediction value of the next adjacent collection time of the target collection time; then, according to the casting temperature prediction value, the temperature of the isothermal quenching of the casting is compensated, so that the component temperature of the isothermal quenching of the casting is kept at the preset target temperature, the stable isothermal quenching of the casting temperature is ensured, the service life of the ADI casting is prolonged, the problem that the simulation temperature and the real temperature of the casting exist difference in the temperature compensation process of the isothermal quenching, resulting in that the performance and quality of the prepared ADI casting do not meet the standards, and the quality of the prepared ADI casting is improved; finally, the air cooling operation and cleaning of the castings completed isothermal quenching are performed, and the isothermal quenching of the austempered ductile iron is completed. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0036] Figure 1 A process flow diagram of an austempered ductile iron isothermal quenching method for prolonging the service life of ADI casting provided by an embodiment of the present application;

[0037] Figure 2 A quenching heat release influence coefficient acquisition flowchart provided by an embodiment of the present application. DETAILED DESCRIPTION

[0038] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0039] Please refer to Figure 1 which shows an isothermal quenching method for prolonging the service life of ADI castings provided by an embodiment of the present application, the method comprising the following steps:

[0040] Step S001, the thickness and surface area of the castings to be isothermally quenched are collected, and the castings are sequentially subjected to preheating treatment, first holding treatment, heating to austenitizing temperature treatment and second holding treatment, the treated castings are transferred to a quenching medium, and the castings are isothermally quenched, and the heat flow and the temperature of the castings at different collection times are collected during the isothermal quenching process.

[0041] The thickness and surface area of the castings to be isothermally quenched are measured.

[0042] The armored thermocouples are fixed on both sides and the center of the hearth of the heating furnace, and the armored thermocouples are used to collect the furnace temperature in real time during the preparation of the austempered ductile iron using the isothermal quenching technology, and the range of the armored thermocouples needs to reach 1000℃ to ensure the accurate acquisition of the furnace temperature during the austenitizing stage. The thermocouples are connected to the temperature measuring parts of the castings using high-temperature resistant glue, and the thermocouples are used to collect the temperature of the castings during the preparation of the austempered ductile iron using the isothermal quenching technology. The armored thermocouples are inserted into the slots at the inlet of the quenching medium and within 10cm from the immersion position of the castings, and the armored thermocouples are used to collect the temperature of the quenching medium during the preparation of the austempered ductile iron using the isothermal quenching technology.

[0043] In order to avoid the interference of electromagnetic noise on the temperature collection process, the furnace temperature, the casting temperature and the quenching medium temperature are denoised respectively.

[0044] In this embodiment, the furnace temperature, the casting temperature and the quenching medium temperature are denoised using wavelet threshold denoising. As other implementation manners, the implementer can use other methods such as Savitzky-Golay filtering, median filtering and the like in the prior art to denoise the furnace temperature, the casting temperature and the quenching medium temperature respectively on the basis of achieving the purpose of denoising the furnace temperature, the casting temperature and the quenching medium temperature respectively, and the present application does not make special limitation.

[0045] Before the austempered ductile iron is prepared by using the austempering technology on the casting, the casting needs to be firstly moved to a heating furnace for preheating, the preheating treatment is performed at a temperature lower than the austenitizing temperature, the temperature rising speed and the preheating temperature are controlled by using a PLC controller, the temperature rising speed is set to be 100℃ per hour in the embodiment, and the preheating temperature is set to be 600℃, so that the casting is prevented from being deformed or cracked due to thermal stress. The casting after the preheating treatment is subjected to a first holding treatment, the holding time of the first holding treatment is determined according to the thickness of the casting, specifically, 2 minutes of holding time is needed per millimeter of thickness of the casting in the embodiment, so as to ensure that the overall temperature of the casting is uniform and the casting can smoothly perform austenite conversion. The casting after the holding treatment is further heated to the austenitizing temperature, the austenitizing temperature is greater than or equal to 850℃ and less than or equal to 950℃, and 900℃ is selected as the austenitizing temperature in the embodiment. The casting heated to the austenitizing temperature is subjected to a second holding treatment, so as to ensure that the overall temperature of the casting is uniform and the ferrite and the pearlite in the casting are completely converted into uniform carbon-saturated austenite, and the holding time is determined according to the thickness of the casting, specifically, 2 minutes of holding time is needed per millimeter of thickness of the casting in the embodiment. The casting is quickly moved to a quenching medium, and the austempering operation is performed on the casting, and the temperature of the quenching medium is set to be 300℃ in the embodiment.

[0046] As other embodiments, on the basis of achieving the purpose of preheating treatment, holding and heating to the austenitizing temperature on the casting, the implementer can set the temperature rising speed and the preheating temperature of the preheating, the holding time and the austenitizing temperature by himself / herself, and the present application does not make special limitation.

[0047] In the process of the austempering on the casting, the heat flow is collected by using a heat flow meter.

[0048] In the process of the austempering on the casting, the heat flow is collected every 10 seconds.

[0049] At this time, the thickness and the surface area of the casting to be austempered, and the heat flow and the casting temperature of the casting at different collection time points in the process of the austempering are obtained.

[0050] In step S002, any one collection time point is recorded as a target collection time point, the quenching heat release influence coefficient of each target collection time point is determined according to the thickness and the surface area of the casting, the heat flow at each collection time point and the time length of the quenching that has been performed, the prediction weight of the target collection time point is determined according to the difference between the quenching heat release influence coefficients of different collection time points adjacent to the target collection time point, and the casting temperature prediction value of the next adjacent collection time point of the target collection time point is obtained by combining the casting temperatures of the target collection time point and different collection time points adjacent to the target collection time point.

[0051] In order to prolong the service life of the ADI casting, when the isothermal quenching operation is performed on the casting, the temperature needs to be kept stable in the standard temperature range to avoid cracks and toughness damage of the casting caused by excessive temperature change. Since the casting after the re-heat treatment still maintains the austenitizing temperature, but the temperature of the quenching medium is obviously lower than the austenitizing temperature, during the process of moving the casting into the quenching medium, both the casting and the quenching medium will have a large temperature fluctuation. In order to ensure the smooth progress of the isothermal quenching operation, the quenching medium needs to be temperature-compensated through simulation of the temperature field or historical temperature change curve. Along with the isothermal quenching, since the quenching process is an exothermic process, the longer the isothermal quenching time is, the higher the ambient temperature around the casting is, which will cause a change in the heat passing through the surface of the casting in the same quenching time, thereby causing a deviation between the simulated casting temperature and the real casting temperature.

[0052] Any collection time in the process of isothermal quenching of the casting is recorded as a target collection time.

[0053] The heat transfer coefficient of the target collection time is calculated according to the thickness and surface area of the casting and the heat flow of the target collection time. The calculation of the heat transfer coefficient is a known technology and will not be repeated here.

[0054] The heat transfer coefficient of each collection time in the process of isothermal quenching of the casting can be obtained in the same way.

[0055] The difference between the heat transfer coefficient of the target collection time and the heat transfer coefficient of the first collection time in the process of isothermal quenching of the casting is recorded as the first difference value of the target collection time; the ratio of the thickness of the casting to the length of time for which the casting has been quenched at the target collection time is recorded as the first ratio value of the target collection time, and the positive correlation processing result of the first difference value and the first ratio value is recorded as the quenching exothermic influence coefficient of the target collection time.

[0056] It can be understood that the first difference value and the first ratio value are positively correlated, that is, the first difference value and the first ratio value are respectively positively correlated with the quenching exothermic influence coefficient. It can be understood that the positive correlation in the present application refers to the relationship between the independent variable and the dependent variable, the independent variable is the first difference value and the first ratio value, and the dependent variable is the quenching exothermic influence coefficient. The positive correlation is that the dependent variable increases (decreases) as the independent variable increases (decreases), which can be an additive relationship, a multiplication relationship, etc.

[0057] Preferably, as an embodiment of the present application, the calculation result of the exponential power with the natural constant as the base and the first difference value of the target collection time as the index is recorded as the first exponential value of the target collection time, and the product of the first exponential value of the target collection time and the first ratio value is recorded as the quenching exothermic influence coefficient of the target collection time.

[0058] The quenching heat release influence coefficient is used to evaluate the influence of the quenching heat release on the casting at the corresponding acquisition time. The quenching heat release influence coefficient acquisition flow chart is shown in Figure 2

[0059] The acquisition time adjacent to the target acquisition time is recorded as the prediction basis time of the target acquisition time.

[0060] The first preset number is represented by the first preset number, and the value of the first preset number in the embodiment is 5. It can be understood that when the acquisition time adjacent to the target acquisition time is less than the first preset number, in order to ensure the accuracy of the temperature step of the target acquisition time, the target acquisition time is not analyzed. The sum of the prediction basis time of the target acquisition time and the quenching heat release influence coefficient of the target acquisition time is recorded as the total quenching heat release influence coefficient of the target acquisition time. The ratio of the quenching heat release influence coefficient of the target acquisition time to the total quenching heat release influence coefficient is recorded as the second ratio of the target acquisition time. The ratio of the number 2 to the time interval of the adjacent acquisition time is recorded as the third ratio of the target acquisition time. The positive correlation processing result of the second ratio and the third ratio of the target acquisition time is recorded as the prediction weight of the target acquisition time.

[0061] In the calculation process of the ratio of the number 2 to the time interval of the adjacent acquisition time, in order to avoid the case that the denominator is zero, a preset value needs to be added to the denominator. The value of the preset value in the embodiment is 1.

[0062] It can be understood that the second ratio and the third ratio are positively correlated, that is, the second ratio and the third ratio are respectively positively correlated with the prediction weight. It can be understood that the positive correlation relationship of the present application refers to the relationship between the independent variable and the dependent variable. The independent variable is the second ratio and the third ratio, and the dependent variable is the prediction weight. The positive correlation relationship is that the dependent variable increases (decreases) with the increase (decrease) of the independent variable, which can be an addition relationship, a multiplication relationship, etc.

[0063] Preferably, as an embodiment of the present application, the product of the second ratio and the third ratio of the target acquisition time is recorded as the prediction weight of the target acquisition time.

[0064] The prediction weight of the target acquisition time is used as the value of the smoothing coefficient. The EMA exponential weighted moving average algorithm is used to obtain the casting temperature prediction value of the next adjacent acquisition time of the target acquisition time according to the casting temperature of the target acquisition time and all prediction basis times of the target acquisition time.

[0065]

[0066] ​​​The EMA exponential moving average algorithm is used to obtain the predicted value, which is a known technology and will not be described herein.

[0067] The next adjacent acquisition time casting temperature prediction value of any acquisition time during the isothermal quenching of the casting can be obtained in the same way.

[0068] In step S003, the casting isothermal quenching is temperature compensated according to the casting temperature prediction value, the casting after isothermal quenching is air cooled and cleaned, and the isothermal quenching of the austempered ductile iron is completed.

[0069] The casting temperature prediction value of the next adjacent acquisition time of the target acquisition time is taken as the casting temperature of the next adjacent acquisition time of the target acquisition time, the power of the resistance heater and the valve opening of the cooling valve are controlled by the PID control algorithm, the isothermal quenching process is temperature compensated, the component temperature of the isothermal quenching of the casting is kept at the preset target temperature, the stable isothermal quenching of the casting temperature is ensured, and the service life of the ADI casting is prolonged.

[0070] The target temperature of the isothermal quenching of the casting is determined by the parameter requirements of the ADI casting. Specifically, the target temperature of the ADI casting with high toughness and low hardness is generally greater than or equal to 300℃ and less than or equal to 400℃, and the target temperature of the ADI casting with high strength and high wear resistance is generally greater than or equal to 220℃ and less than or equal to 300℃. The power of the resistance heater and the valve opening of the cooling valve are controlled by the PID control algorithm, so that the component temperature of the isothermal quenching of the casting is kept at the preset target temperature. The specific process is a known technology and will not be described herein.

[0071] The isothermal quenching time of the casting is determined according to the thickness of the casting. Specifically, the isothermal quenching time of 2 minutes per millimeter thickness of the casting is set in the embodiment.

[0072] By accurately controlling the temperature and time of the isothermal quenching of the casting, the directional regulation of the casting material organization is realized, the isothermal transformation of austenite to bainite is promoted, and the casting can be transformed into upper bainite with high toughness and low hardness, or lower bainite with high strength and high wear resistance according to the parameter requirements of the ADI casting.

[0073] The casting after isothermal quenching is taken out and air cooled, the casting temperature is air cooled to room temperature, and the residual quenching medium of the casting is removed using hot water or special equipment after the casting is cooled, and the isothermal quenching operation of the austempered ductile iron for prolonging the service life of the casting is completed.

[0074] Thus, the isothermal quenching of the austempered ductile iron is completed.

[0075] The above description is only the preferred embodiment of the present application, and is not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the principle of the present application should be included in the protection scope of the present application.

Claims

1. An austempering process for extending the life of ADI castings, characterized in that, The method comprises the following steps: Collecting the thickness and surface area of the castings to be isothermal quenched, sequentially performing preheating treatment, first holding treatment, heating to austenitizing temperature treatment and second holding treatment on the castings, transferring the treated castings to a quenching medium, and isothermally quenching the castings, collecting the heat flow and the temperature of the castings at different collection time points during the isothermal quenching process; Any one collection time point is recorded as a target collection time point, the quenching heat release influence coefficient of each target collection time point is determined according to the thickness and surface area of the castings, the heat flow at each collection time point and the length of time that has been quenched, the prediction weight of the target collection time point is determined according to the difference between the quenching heat release influence coefficients of adjacent collection time points adjacent to the target collection time point, and the casting temperature prediction value of the next adjacent collection time point of the target collection time point is obtained in combination with the casting temperatures of the target collection time point and the adjacent collection time points adjacent to the target collection time point; The isothermal quenching of the castings is compensated according to the casting temperature prediction value, the isothermally quenched castings are subjected to air cooling operation and cleaning, and the isothermal quenching of the austempered ductile iron is completed; The specific method of determining the quenching heat release influence coefficient of each target collection time point according to the thickness and surface area of the castings, the heat flow at each collection time point and the length of time that has been quenched comprises: The heat conduction coefficient of the target collection time point is calculated according to the thickness and surface area of the castings and the heat flow at the target collection time point; The quenching heat release influence coefficient of the target collection time point is determined according to the difference between the heat conduction coefficients of the first collection time point and the target collection time point for isothermal quenching of the castings, the thickness of the castings and the length of time that the castings have been quenched at the target collection time point; The specific method of determining the prediction weight of the target collection time point according to the difference between the quenching heat release influence coefficients of adjacent collection time points adjacent to the target collection time point comprises: The first preset number of adjacent collection time points before the target collection time point are all recorded as prediction basis time points of the target collection time point; A second ratio of the target collection time point is determined according to the quenching heat release influence coefficients of the prediction basis time points of the target collection time point and the target collection time point; A third ratio of the target collection time point is recorded as the ratio of the time interval between adjacent collection time points; A positive correlation processing result of the second ratio and the third ratio of the target collection time point is recorded as the prediction weight of the target collection time point; The method for obtaining the casting temperature prediction value of the next adjacent collection time point of the target collection time point comprises: The prediction weight of the target collection time point is taken as the value of the smoothing coefficient, and data prediction is performed according to the casting temperatures of the target collection time point and all the prediction basis time points of the target collection time point, so as to obtain the casting temperature prediction value of the next adjacent collection time point of the target collection time point.

2. The austempering method of extending the life of ADI castings according to claim 1, characterized in that, The holding time for the first holding treatment and the second holding treatment of the castings is: 2 minutes of holding time per millimeter of thickness of the castings.

3. The austempering method of extending the life of ADI castings according to claim 1, characterized in that, The austenitizing temperature in the austenitizing temperature treatment process should be: Greater than or equal to 850 DEG C and less than or equal to 950 DEG C.

4. The austempering method of extending the life of ADI castings according to claim 1, characterized in that, The difference between the thermal conductivity coefficient of the first collection time when the casting is isothermally quenched and the target collection time, the thickness of the casting, and the length of time the casting has been quenched at the target collection time are used to determine the quenching heat release influence coefficient of the target collection time, including the specific method: The difference between the thermal conductivity coefficient of the target collection time and the thermal conductivity coefficient of the first collection time when the casting is isothermally quenched is recorded as the first difference value of the target collection time. The ratio of the thickness of the casting to the length of time the casting has been quenched at the target collection time is recorded as the first ratio value of the target collection time. The positive correlation processing result of the first difference value and the first ratio value of the target collection time is recorded as the quenching heat release influence coefficient of the target collection time.

5. The austempering method of extending the life of ADI castings according to claim 1, characterized in that, The second ratio value of the target collection time is determined according to the predicted basis time of the target collection time and the quenching heat release influence coefficient of the target collection time, including the specific method: The cumulative sum of the predicted basis time of the target collection time and the quenching heat release influence coefficient of the target collection time is recorded as the total quenching heat release influence coefficient of the target collection time, and the ratio of the quenching heat release influence coefficient of the target collection time to the total quenching heat release influence coefficient is recorded as the second ratio value of the target collection time.

6. The austempering method of extending the life of ADI castings according to claim 1, characterized in that, The casting is temperature-compensated for isothermal quenching according to the casting temperature prediction value, including the specific method: The casting temperature prediction value of the next adjacent collection time of the target collection time is used as the casting temperature of the next adjacent collection time of the target collection time, so that the component temperature of the isothermal quenching of the casting maintains the preset target temperature, achieving temperature compensation in the isothermal quenching process.

7. The austempering method of extending the life of ADI castings according to claim 1, characterized in that, The casting that has completed isothermal quenching is subjected to air cooling operation and cleaning, including the specific method: The casting temperature is air-cooled to room temperature, and the residual quenching medium of the casting is removed.

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