Irregular metal forge piece heat treatment method and system

Abstract

The invention relates to the technical field of metal forge piece machining, in particular to an irregular metal forge piece heat treatment method and system.The irregular metal forge piece heat treatment method comprises the steps that firstly, temperature compensation partitions are divided according to geometrical characteristics, and stepped preheating is implemented to establish a uniform basic temperature field; then, the heat preservation time of each subarea is independently regulated and controlled in the austenitizing stage, and sufficient transformation of a thick-wall area structure and control over the grain size of a thin-wall area are both considered; in the quenching process, partition strength adjustment is carried out based on a preset cooling map, and cooling parameters are dynamically optimized through real-time feedback; and finally, according to the residual stress distribution, carrying out partition stepped tempering. The heating and cooling uniformity is remarkably improved through partition dynamic temperature management, and the structure difference and thermal stress concentration caused by section sudden change are effectively inhibited; the microstructure is ensured to be uniform and stable through austenitizing control; the hardenability and the deformation resistance are balanced through a differential cooling strategy; and directional reduction of residual stress is achieved through an intelligent tempering mechanism, and the cracking risk is greatly reduced while the comprehensive mechanical property is improved.

Description

Technical Field

[0001] The present application relates to the technical field of metal forging processing, and in particular to a method and system for heat treatment of irregular metal forgings. Background Art

[0002] Heating and cooling metal forgings are crucial for determining their ultimate performance. Heating requires uniform, through-burning within a specific temperature range (e.g., 1100-1250°C for carbon steel) to enhance plasticity and complete austenitization. However, overheating (coarsening of grains), overburning (grain boundary melting), and surface oxidation and decarburization must be avoided. The cooling process is even more critical: the cooling rate directly influences microstructural transformation and stress distribution. Air cooling, pit cooling, or furnace cooling are used to slow cooling to prevent cracking. Quenching achieves rapid hardening, but immediate tempering is required to eliminate brittleness. Uneven cooling can lead to three hazards: differential shrinkage between the surface and core creates thermal stresses, and asynchronous phase transformation generates structural stresses. The combined effects of these two factors can easily lead to cracking or deformation in the forging. Furthermore, uneven grain size and hardness fluctuations (e.g., martensite on the surface and pearlite in the core) can result, along with residual harmful internal stresses, significantly reducing fatigue life and dimensional stability. Therefore, precise and coordinated temperature control based on material properties and forging structure is crucial to avoid a chain reaction of defects.

[0003] In the existing technology, due to the shape and size of metal forgings, parts close to the edge, small parts and thin-walled parts often cool down faster, while corners and thick parts often cool down slower. The grains in the fast cooling zone are small or form hard and brittle structures (such as martensite), and the grains in the slow cooling zone are coarse or form soft structures (such as ferrite + pearlite). This leads to extremely uneven distribution of hardness, strength and toughness inside the forging, the appearance of soft spots or hard spots, and even cracking, deformation and scrapping of the forging, or uneven structural properties, excessive residual stress, etc. Summary of the Invention

[0004] The purpose of this application is to provide a method and system for heat treatment of irregular metal forgings, so as to solve the problems of microstructure and performance differences, residual stress concentration and excessive deformation caused by delayed heat conduction and uneven cooling in traditional heat treatment processes through the synergistic effect of zoned temperature field control, multi-modal austenitization regulation, gradient cooling strength adaptation and stress-guided tempering technology.

[0005] In a first aspect, an embodiment of the present application provides a method for heat treating an irregular metal forging, comprising:

[0006] S100, zone gradient preheating, divides the forging into multiple temperature compensation zones according to its three-dimensional geometric characteristics, and implements step-by-step preheating for each temperature compensation zone to make the temperature difference between the surface and the core ≤50°C to establish the basic temperature field;

[0007] S200, multi-modal austenitization. After reaching the austenitizing temperature, multiple independent temperature control units in different temperature compensation zones are used to independently adjust and maintain the actual holding time of each zone at the austenitizing temperature based on the heat capacity and geometric characteristics of each zone.

[0008] S300, zoned controlled intensity cooling, quenches and cools austenitized forgings. During the cooling process, differentiated cooling intensities are applied to different areas of the forging using independently adjustable cooling nozzles in multiple temperature-compensated zones, based on the heat capacity, geometric characteristics, and preset cooling intensity maps of each area.

[0009] S400, stress-guided tempering, performs zone heating on different temperature compensation zones according to the residual stress distribution map, and simultaneously performs full-area step-down tempering.

[0010] In some embodiments, step S100 includes:

[0011] S110, based on the wall thickness mutation rate identification of the 3D forging model, each geometric transition zone with a thickness gradient ≥ 15 mm / cm is defined as a temperature compensation zone.

[0012] S120, in the first stage, the temperature is raised to 300℃ at a rate of ≤60℃ / h and kept at that temperature;

[0013] S130, in the second stage, isothermal holding is performed for the temperature compensation partition with an additional maximum thickness value (mm) and a duration of 2 minutes;

[0014] S140, the third stage is to raise the temperature to the austenitizing temperature at a rate of 80-100℃ / h.

[0015] In some embodiments, step S200 includes:

[0016] S210, for the temperature compensation partition whose cross-sectional thickness is greater than a preset value, the heating mode is calculated based on its maximum cross-sectional thickness to ensure that the core is fully austenitized;

[0017] S220, for a temperature compensation partition whose cross-sectional thickness is less than or equal to a preset value, a heating mode is calculated based on its minimum effective thickness, and an upper limit is set to prevent excessive grain growth;

[0018] S230: For temperature compensation zones with a cross-sectional thickness greater than a preset value, heating is performed in a pulsed rapid heating mode (≥120°C / h). For temperature compensation zones with a cross-sectional thickness less than or equal to a preset value, heating is performed in a slow heating mode (≤80°C / h) until the entire zone reaches the austenitizing temperature.

[0019] In some embodiments, in step S300, applying differentiated cooling intensities to different regions of the forging includes:

[0020] a. For temperature compensation zones with a thickness greater than a preset value, high-intensity cooling is set;

[0021] b. For temperature compensation zones with a cross-section thickness less than or equal to the preset value, medium and low intensity cooling is set;

[0022] c. For complex inner cavity areas such as inner holes and narrow grooves, medium-intensity cooling is performed using a directional injection of high-permeability cooling medium.

[0023] In some embodiments, step S300 further includes:

[0024] S310, dynamic feedback control, monitors the surface temperature change rate of different temperature compensation zones of the forging in real time during the cooling process. Based on the deviation between the monitored actual cooling rate and the preset target cooling rate, the parameters of the corresponding temperature compensation zone cooling nozzle group are dynamically adjusted to make the actual cooling rate approach the target value.

[0025] In some embodiments, step S310 includes:

[0026] S311, collecting temperature data of monitoring points of each temperature compensation partition in real time and calculating its instantaneous cooling rate;

[0027] S312, comparing the calculated instantaneous cooling rate with the temperature-compensated partition target cooling rate curve;

[0028] S313, if the measured rate is higher than the target rate, the flow rate or pressure of the cooling nozzle group responsible for the temperature compensation partition is reduced; if the measured rate is lower than the target rate, the flow rate or pressure of the cooling nozzle group responsible for the temperature compensation partition is increased.

[0029] In some embodiments, step S400 includes:

[0030] S410, heating to the first tempering temperature at a rate of 40-60°C / hour and holding the temperature for 3 minutes per the maximum cross-sectional dimension of the forging (mm);

[0031] S420, heating to the second tempering temperature at a rate of 30-50°C / hour, holding time is the maximum cross-sectional dimension of the forging in mm / 6 minutes;

[0032] S430, when the temperature exceeds the set threshold, it automatically reduces the heating rate by 5-10℃ / h and extends the holding time by 20%-30%

[0033] S440, furnace cooled to below 300°C and then air cooled.

[0034] A second aspect of the present application provides a system for heat treating irregular metal forgings, comprising:

[0035] Gradient partitioning module, used to scan the three-dimensional geometric features of the forging and divide the temperature compensation zones according to the three-dimensional geometric features of the forging;

[0036] Multi-source array heating module, which heats the temperature compensation zones;

[0037] A temperature control module is used to monitor the surface temperature and rate of change of key areas of the forging, independently adjust and maintain the actual holding time of each area at the austenitizing temperature based on the heat capacity and geometric characteristics of each area, and determine the differentiated cooling intensity applied to different areas of the forging based on the geometric characteristics, material properties and preset cooling intensity maps of each area of ​​the forging;

[0038] Cooling nozzle groups are used to apply differentiated cooling intensity to different areas of the forging.

[0039] In some embodiments, the cooling nozzle group includes at least:

[0040] a first nozzle assembly covering the upper surface of the forging body;

[0041] a second nozzle assembly covering the lower surface and bottom corners of the forging body;

[0042] The third nozzle group targets the side walls and protruding ribs of forgings;

[0043] A fourth dedicated internal cooling nozzle group for internal holes and groove features of forgings;

[0044] The cooling medium type, flow rate and pressure of each group of nozzles can be set and adjusted independently.

[0045] A third aspect of the present application provides a non-volatile storage medium storing a computer program, which implements the steps of the above-mentioned heat treatment method when executed by a processor.

[0046] The beneficial effects of this application are as follows: for irregular metal forgings, first, the temperature compensation zones are divided according to the geometric characteristics, and step-by-step preheating is implemented to establish a uniform basic temperature field; then, the holding time of each zone is independently regulated during the austenitization stage, taking into account both the full transformation of the thick-walled zone and the grain size control of the thin-walled zone; the quenching process is based on the preset cooling map to adjust the zone strength, and the cooling parameters are dynamically optimized through real-time feedback; finally, the zone step tempering is implemented according to the residual stress distribution. The heating and cooling uniformity is significantly improved through the dynamic temperature management of the zones, and the organizational differences and thermal stress concentration caused by cross-sectional mutations are effectively suppressed; the microstructure is ensured to be uniform and stable through austenitization control; the hardenability and deformation resistance are balanced through differentiated cooling strategies; the intelligent tempering mechanism realizes the directional reduction of residual stress, which greatly reduces the risk of cracking while improving the overall mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a flow chart of the irregular metal forging heat treatment method in this application;

[0048] Figure 2 Flowchart for preheating the partitioned gradient in this application;

[0049] Figure 3 Flowchart of multimodal austenitization in this application;

[0050] Figure 4 This is a flow chart of dynamic feedback control in this application;

[0051] Figure 5 Flowchart for stress-guided tempering in this application;

[0052] Figure 6 This is a module diagram of the irregular metal forging heat treatment system in this application. DETAILED DESCRIPTION

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0054] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0055] In the embodiments provided in this application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the module, program segment or a part of the code contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or can be implemented using a combination of dedicated hardware and computer instructions.

[0056] In addition, the functional modules in each embodiment of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0057] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, and other media that can store program code.

[0058] Irregular metal forgings face several problems during the heat treatment process. Due to the shape and size of metal forgings, parts close to the edge, small parts and thin-walled parts often cool down faster, while corners and thick parts often cool down slower. The grains in the fast cooling zone are small or form hard and brittle structures (such as martensite), while the grains in the slow cooling zone are coarse or form soft structures (such as ferrite + pearlite). This leads to extremely uneven distribution of hardness, strength and toughness inside the forging, the appearance of soft spots or hard spots, and even cracking, deformation and scrapping of the forging, or uneven structural properties and excessive residual stress.

[0059] Traditional forging heat treatment utilizes an overall uniform heating and cooling pattern. For irregular components with a wall thickness mutation rate ≥15 mm / cm, the maximum temperature difference between the surface and the core during the heating phase often exceeds 150°C. The actual holding time of thin-walled areas during the austenitization holding phase exceeds that of thick-walled areas by 40%-60%. During the quenching cooling phase, the cooling rate of thin-walled areas can reach over 2.5 times that of thick-walled areas. This thermal process heterogeneity results in microstructural variations exceeding 30%, hardness fluctuations exceeding 5 HRC, and residual stress peaks exceeding 70% of the material's yield strength. Existing technologies attempt to improve this through local shielding or zoned spraying, but due to the lack of a dynamic coupling model between geometric features and thermal parameters, actual control accuracy is insufficient, and temperature differential control errors remain significant.

[0060] In view of this, a first aspect of the present application provides a method and system for heat treatment of irregular metal forgings.

[0061] Example 1

[0062] Reference Figure 1 In a first aspect, an embodiment of the present application provides a method for heat treating an irregular metal forging, comprising:

[0063] S100, zone gradient preheating, divides the forging into multiple temperature compensation zones according to its three-dimensional geometric characteristics, and implements step-by-step preheating for each temperature compensation zone to make the temperature difference between the surface and the core ≤50°C to establish the basic temperature field;

[0064] Reference Figure 2 In some embodiments, step S100 includes:

[0065] S110, based on the wall thickness mutation rate identification of the 3D forging model, each geometric transition zone with a thickness gradient ≥15mm / cm is demarcated as a temperature compensation zone. At the same time, the curvature radius analysis method is used to assist in thickness gradient identification. When the surface curvature radius R is less than 50mm and the thickness difference Δδ between adjacent areas is ≥40mm, it is forcibly divided into a mutation compensation zone.

[0066] S120, in the first stage, the temperature is raised to 300℃ at a rate of ≤60℃ / h and kept at that temperature;

[0067] Heat to 300℃ at a rate of 55±5℃ / h and keep warm for 2.5-3 hours to eliminate more than 60% of machining stress. At the same time, collect the internal temperature every 15 minutes. If the difference between the internal temperature and the surface temperature is greater than 18℃ at the end of the 300℃ holding period, extend the holding time until the temperature difference is ≤12℃.

[0068] S130, in the second stage, isothermal holding is performed for the temperature compensation partition with an additional maximum thickness value (mm) and a duration of 2 minutes;

[0069] For partitions with a maximum thickness of ≥100mm, press T=( / 2)Minutes calculation ( The unit is mm). For example, a 300mm thick area is kept warm for 150 minutes to converge the cross-section temperature difference to within 35°C. At the same time, an additional compensation time of thickness value mm / 4 minutes is applied to the sudden compensation partition (such as the connection between the boss and the substrate).

[0070] S140, the third stage is to raise the temperature to the austenitizing temperature at a rate of 80-100℃ / h.

[0071] Heat the material to the austenitizing temperature (e.g. 860°C, determined according to the material) at a rate of 90±10°C / h. At the end of the heating period, the temperature difference between the surface and the interior should be ≤45°C. At the same time, pause the heating at 500°C and 700°C for 15 minutes respectively for temperature balance.

[0072] S200, multi-modal austenitization, after reaching the austenitizing temperature, uses multiple independent temperature control units in different temperature compensation zones to independently adjust and maintain the actual holding time of each zone at the austenitizing temperature based on the heat capacity and geometric characteristics of each zone; the austenitizing temperature field is established using PID-fuzzy composite control to enhance the system's robustness, adaptability and control accuracy.

[0073] Reference Figure 3 In some embodiments, step S200 includes:

[0074] S210, for the temperature compensation partition whose cross-sectional thickness is greater than a preset value, the heating mode is calculated based on its maximum cross-sectional thickness to ensure that the core is fully austenitized;

[0075] In this embodiment, the preset thickness threshold is 100 mm. >100mm thick wall area, when the distance from the surface When the temperature at the depth reaches Ac3+10℃, the effective insulation time begins to be calculated.

[0076] S220: For temperature compensation partitions with a cross-sectional thickness less than or equal to a preset value, the heating mode is calculated based on its minimum effective thickness and an upper limit is set to prevent excessive grain growth; the grain growth control adopts a dual constraint mechanism: the upper limit of the heating time of the thin-walled zone ≤ (0.06 x ) min, and the upper temperature limit is not more than Ac3+40℃.

[0077] S230, for the temperature compensation partition with a cross-sectional thickness greater than the preset value, a pulse type rapid heating mode (≥120℃ / h) is used, and for the temperature compensation partition with a cross-sectional thickness less than or equal to the preset value, a slow heating mode (≤80℃ / h) is used, until the whole domain reaches the austenitizing temperature.

[0078] The pulse rapid heating mode uses a transient heating rate of 10-15℃ / min, but the duration of each pulse is ≤3 minutes, and the pulse interval is ≥5 minutes, so that the temperature field is redistributed; the slow heating mode is reduced to 60℃ / h above 600℃, so that the austenitizing degree of the thick wall zone core is 98%, the grain size of the thin wall zone is controlled at ASTM 7-8 level, and the uniformity deviation of the structure is <15%.

[0079] S300, partition controllable strength cooling, quenching cooling is performed on the forged piece after austenitizing, during the cooling process, according to the heat capacity, geometric characteristics and preset cooling strength map of each region of the forged piece, a plurality of temperature compensation partitions with independently adjustable cooling nozzles are used to apply differential cooling strength to different regions of the forged piece; wherein the cooling strength map is a cooling rate temperature change curve preset according to the material of the metal forged piece and the strength that can be reached.

[0080] During the cooling process, the airflow path planning is generated based on the three-dimensional model of the forged piece, and the airflow impact angle is periodically changed during the heating process through the rotatable cooling nozzle group, and the angle change range is ±15°-±45°, so that the uniform cooling effect of each position of the irregular forged piece is realized.

[0081] In some embodiments, in step S300, the differential cooling strength is applied to different regions of the forged piece, including:

[0082] a. For the temperature compensation partition with a cross-sectional thickness greater than the preset value, high strength cooling is set; in this embodiment, high strength cooling (cooling rate ≥45℃ / s) is started for the region with a thickness >150mm, and the nozzle pressure is set to 0.8-1.2MPa.

[0083] b. For the temperature compensation partition with a cross-sectional thickness less than or equal to the preset value, medium-low strength cooling is set; medium-low strength cooling (cooling rate 15-25℃ / s) is used for the region with a thickness ≤50mm, and the pressure is reduced to 0.3-0.5MPa.

[0084] c. For complex internal cavities such as inner holes and narrow slots, medium-intensity cooling is achieved through directional injection of a high-permeability cooling medium. For inner hole and narrow slot areas, a high-permeability cooling medium containing nano-ceramic particles is used. The injection angle is controlled within ±15°, and the cooling rate is maintained at 20±2°C / s. The cooling medium temperature is maintained at 30±2°C, with a concentration fluctuation of less than 1.5%.

[0085] In some embodiments, step S300 further includes:

[0086] S310, dynamic feedback control, monitors the surface temperature change rate of different temperature compensation zones of the forging in real time during the cooling process. Based on the deviation between the monitored actual cooling rate and the preset target cooling rate, the parameters of the corresponding temperature compensation zone cooling nozzle group are dynamically adjusted to make the actual cooling rate approach the target value.

[0087] Reference Figure 4 , wherein step S310 includes:

[0088] S311, collecting temperature data of monitoring points of each temperature compensation partition in real time and calculating its instantaneous cooling rate;

[0089] Among them, the instantaneous cooling rate V is calculated using the five-point central difference method:

[0090]

[0091] Among them, the time step =0.2s, the temperature data comes from the thermocouple array arranged according to the isothermal line in each temperature compensation zone, and the point density is:

[0092] Areas with thickness ≥100 mm: one temperature measuring point is arranged for every 50 mm × 50 mm area;

[0093] Thickness <100 mm: Arrange one temperature measurement point for every 80 mm × 80 mm area; thermocouple response time ≤ 0.1 second, temperature measurement accuracy ±0.8°C.

[0094] S312, comparing the calculated instantaneous cooling rate with the temperature-compensated partition target cooling rate curve;

[0095] Set the dynamic dead zone threshold in the rate comparison link:

[0096] When the temperature is >500℃ (austenite stable zone), the dead zone range is ±4℃ / s;

[0097] When the temperature is 300℃≤≤500℃ (pearlite transformation zone), the dead zone is reduced to ±2℃ / s;

[0098] When the temperature is <300℃ (martensite transformation zone), the dead zone expands to ±5℃ / s.

[0099] The comparator performs a deviation analysis every 0.25 seconds and triggers an adjustment command when three consecutive samples exceed the dead band to avoid actuator oscillation.

[0100] S313, if the measured rate is higher than the target rate, the flow rate or pressure of the cooling nozzle group responsible for the temperature compensation partition is reduced; if the measured rate is lower than the target rate, the flow rate or pressure of the cooling nozzle group responsible for the temperature compensation partition is increased.

[0101] The execution and control link adopts a two-level linkage mechanism:

[0102] Primary regulation: The cooling medium flow is adjusted by the proportional integral valve, and the flow change slope ;

[0103] When the cooling rate needs to be reduced, the flow rate is reduced by 3.5% for every 1°C / s deviation; when the cooling rate needs to be increased, the upper limit of the flow rate increase is 120% of the base value.

[0104] Secondary regulation: When the flow regulation reaches the limit and still does not meet the requirements, the pressure compensation system is activated:

[0105] Boost mode: pressure increase gradient =0.05 MPa / (℃ / s); Decompression mode: the pressure can be reduced to 0.15 MPa.

[0106] Among them, the actuator response time is <0.3 seconds, the flow control linearity is ≥0.97, and the two-stage regulation effectively reduces the cooling rate tracking lag and improves the target cooling rate achievement rate.

[0107] S400, stress-guided tempering, uses residual stress distribution maps to heat different temperature compensation zones and simultaneously conducts global step-down tempering. Residual stresses are detected through X-ray diffraction, and the tempering temperature curve is dynamically adjusted based on real-time stress detection data to generate a compensation strategy.

[0108] Reference Figure 5 In some embodiments, step S400 includes:

[0109] S410, heating to the first tempering temperature at a rate of 40-60°C / hour and holding the temperature for 3 minutes per the maximum cross-sectional dimension of the forging (mm);

[0110] 300℃→400℃ range: 60±5℃ / h to accelerate through the hydrogen embrittlement sensitive area; 400℃→target temperature range: reduce the speed to 45±5℃ / h to avoid the temper embrittlement sensitive area;

[0111] Press the maximum cross-sectional size of the forging for a long time during insulation Calculated as T1 = / 3 minutes, e.g. = 300mm, keep warm for 100 minutes. = 450 mm, then keep warm for 150 minutes to fully eliminate residual stress and hardness uniformity deviation.

[0112] S420, heating to the second tempering temperature at a rate of 30-50°C / hour, holding time is the maximum cross-sectional dimension of the forging in mm / 6 minutes;

[0113] Continue to heat up to the second tempering temperature at a rate of 40±2℃ / h, set in the range of Ac1-70℃ to Ac1-50℃, and insert a 30-minute temperature platform at 550℃, where the holding time T2 = / 6 minutes, e.g. =300mm, keep warm for 50 minutes; among them, for materials with hydrogen content greater than 2.5 ppm, add 120 minutes of keeping warm in the range of 350-450℃ to reduce the spheroidization rate of grain boundary carbides.

[0114] S430, when the temperature exceeds the set threshold, it automatically reduces the heating rate by 5-10℃ / h and extends the holding time by 20%-30%

[0115] Specifically, the over-temperature protection mechanism adopts a three-level response strategy:

[0116] When the overtemperature range is >15°C, the cooling rate is reduced by 5-10°C / h. In this application, it is reduced by 8°C / h, and the holding time is extended by 20%-30%. In this application, the holding time is extended by 25%.

[0117] When the over-temperature range is greater than 25°C, inert gas is injected to force cooling, and an audible and visual alarm is triggered, and the process is suspended;

[0118] When the over-temperature range is >40℃, the water cooling coil system is started urgently, the process is terminated and fault diagnosis is performed.

[0119] S440, furnace cooled to below 300°C and then air cooled.

[0120] Phase-change driven cooling is implemented during the furnace cooling process: in the high-temperature section (tempering temperature - 500°C), the cooling rate is ≤35°C / h; in the medium-temperature section (500-400°C), the cooling rate is reduced to ≤25°C / h to avoid the temper brittle zone; in the low-temperature section (400-300°C), the cooling rate is maintained at ≤28°C / h. When the temperature drops to 300±10°C, the steel is transferred to still air for cooling. Anti-oxidation treatment is immediately performed after leaving the furnace.

[0121] For irregular metal forgings, temperature compensation zones are first divided according to geometric features, and step-by-step preheating is implemented to establish a uniform base temperature field. Subsequently, during the austenitization stage, the holding time of each zone is independently controlled, taking into account both the full transformation of the thick-walled zone and the grain size control of the thin-walled zone. During the quenching process, the zone strength is adjusted based on a preset cooling map, and cooling parameters are dynamically optimized through real-time feedback. Finally, zone-by-zone step tempering is implemented based on the residual stress distribution. Dynamic temperature management of the zones significantly improves heating and cooling uniformity, effectively suppressing structural differences and thermal stress concentration caused by cross-sectional mutations. Austenitization control ensures uniform and stable microstructure. Differentiated cooling strategies balance hardenability and deformation resistance. An intelligent tempering mechanism achieves directional reduction of residual stress, significantly reducing the risk of cracking while improving overall mechanical properties.

[0122] Example 2

[0123] Reference Figure 6 In a second aspect, the present application provides a heat treatment system for irregular metal forgings, comprising:

[0124] A gradient partitioning module is used to scan the three-dimensional geometric features of the forging and divide the temperature compensation zones according to the three-dimensional geometric features of the forging; it includes a file acquisition unit for determining the size according to the drawing, and a three-dimensional solid scanning unit;

[0125] A multi-source array heating module is used to heat the temperature compensation zones; it includes infrared heating components and laser-assisted heating components arranged in arrays at multiple locations;

[0126] The temperature control module is used to monitor the surface temperature and rate of change of key areas of the forging. Based on the heat capacity and geometric characteristics of each area, it independently adjusts and maintains the actual holding time of each area at the austenitizing temperature. In addition, it determines the differentiated cooling intensity applied to different areas of the forging based on the geometric characteristics, material properties and preset cooling intensity maps of each area of ​​the forging. It includes multiple thermocouple arrays set at different locations on the forging and temperature sensors distributed at different locations.

[0127] Cooling nozzle groups are used to apply differentiated cooling intensity to different areas of the forging.

[0128] In some embodiments, the cooling nozzle groups are spatially distributed to include at least: a first nozzle group covering the upper surface of the forging body; a second nozzle group covering the lower surface and bottom corners of the forging body; a third nozzle group targeting the sidewalls and protruding ribs of the forging; and a fourth dedicated internal cooling nozzle group targeting the internal holes and groove features of the forging.

[0129] The cooling medium type, flow rate and pressure of each group of nozzles can be set and adjusted independently.

[0130] Example 3

[0131] A third aspect of the present application provides a non-volatile storage medium storing a computer program, which implements the steps of the above-mentioned heat treatment method when the program is executed by a processor.

[0132] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

[0133] It will be apparent to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above and that the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present application is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A method for heat treatment of irregular metal forgings, characterized in that: include: S100, zone gradient preheating, divides the forging into multiple temperature compensation zones according to its three-dimensional geometric characteristics, and implements step-by-step preheating for each temperature compensation zone to make the temperature difference between the surface and the core ≤50°C to establish the basic temperature field; S200, multi-modal austenitization, after reaching the austenitizing temperature, using multiple independent temperature control units in different temperature compensation zones to independently adjust and maintain the actual holding time of each zone at the austenitizing temperature based on the heat capacity and geometric characteristics of each zone; S300, zoned controlled intensity cooling, quenches and cools the austenitized forgings. During the cooling process, differentiated cooling intensities are applied to different areas of the forging through independently adjustable cooling nozzle groups with multiple temperature-compensated zones, based on the heat capacity, geometric characteristics, and preset cooling intensity maps of each area of ​​the forging. S400, stress-guided tempering, performs zone heating on different temperature compensation zones according to the residual stress distribution map, and simultaneously performs full-area step-down tempering.

2. The irregular metal forging heat treatment method according to claim 1, characterized in that: Step S100 includes: S110, based on the wall thickness mutation rate identification of the 3D forging model, each geometric transition zone with a thickness gradient ≥ 15 mm / cm is defined as a temperature compensation zone. S120, in the first stage, the temperature is raised to 300℃ at a rate of ≤60℃ / h and kept at that temperature; S130, in the second stage, isothermal holding is performed for the temperature compensation partition with an additional maximum thickness value (mm) and a duration of 2 minutes; S140, the third stage is to raise the temperature to the austenitizing temperature at a rate of 80-100℃ / h.

3. The heat treatment method for irregular metal forgings according to claim 1, characterized in that: Step S200 includes: S210, for the temperature compensation partition whose cross-sectional thickness is greater than a preset value, the heating mode is calculated based on its maximum cross-sectional thickness to ensure that the core is fully austenitized; S220, for a temperature compensation partition whose cross-sectional thickness is less than or equal to a preset value, a heating mode is calculated based on its minimum effective thickness, and an upper limit is set to prevent excessive grain growth; S230: For temperature compensation zones with a cross-sectional thickness greater than a preset value, heating is performed in a pulsed rapid heating mode (≥120°C / h). For temperature compensation zones with a cross-sectional thickness less than or equal to a preset value, heating is performed in a slow heating mode (≤80°C / h) until the entire zone reaches the austenitizing temperature.

4. The heat treatment method for irregular metal forgings according to claim 1, characterized in that: In step S300, differential cooling intensities are applied to different regions of the forging, including: For temperature compensation zones with a section thickness greater than a preset value, high-intensity cooling is set; For temperature compensation zones with a section thickness less than or equal to the preset value, medium and low intensity cooling is set; For complex inner cavity areas such as inner holes and narrow slots, medium-intensity cooling is performed using a directional spray of high-permeability cooling medium.

5. The heat treatment method for irregular metal forgings according to claim 1, characterized in that: Step S300 also includes: S310, dynamic feedback control, monitors the surface temperature change rate of different temperature compensation partitions of the forging in real time during the cooling process, and dynamically adjusts the parameters of the corresponding temperature compensation partition cooling nozzle group based on the deviation between the monitored actual cooling rate and the preset target cooling rate, so that the actual cooling rate approaches the target value.

6. The irregular metal forging heat treatment method according to claim 5, characterized in that: Step S310 includes: S311, collecting temperature data of monitoring points of each temperature compensation partition in real time and calculating its instantaneous cooling rate; S312, comparing the calculated instantaneous cooling rate with the temperature-compensated partition target cooling rate curve; S313, if the measured rate is higher than the target rate, the flow rate or pressure of the cooling nozzle group responsible for the temperature compensation partition is reduced; if the measured rate is lower than the target rate, the flow rate or pressure of the cooling nozzle group responsible for the temperature compensation partition is increased.

7. The irregular metal forging heat treatment method according to claim 1, characterized in that: Step S400 includes: S410, heating to the first tempering temperature at a rate of 40-60°C / hour and holding the temperature for 3 minutes per the maximum cross-sectional dimension of the forging (mm); S420, heating to the second tempering temperature at a rate of 30-50°C / hour, holding time is the maximum cross-sectional dimension of the forging in mm / 6 minutes; S430, when the monitored temperature exceeds the set threshold, it automatically reduces the heating rate by 5-10℃ / h and extends the holding time by 20%-30%; S440, furnace cooled to below 300°C and then air cooled.

8. A heat treatment system for irregular metal forgings, characterized in that: include: Gradient partitioning module, used to scan the three-dimensional geometric features of the forging and divide the temperature compensation zones according to the three-dimensional geometric features of the forging; Multi-source array heating module, which heats the temperature compensation zones; A temperature control module is used to monitor the surface temperature and rate of change of key areas of the forging, independently adjust and maintain the actual holding time of each area at the austenitizing temperature based on the heat capacity and geometric characteristics of each area, and determine the differentiated cooling intensity applied to different areas of the forging based on the geometric characteristics, material properties and preset cooling intensity maps of each area of ​​the forging; Cooling nozzle groups are used to apply differentiated cooling intensity to different areas of the forging.

9. The irregular metal forging heat treatment system according to claim 8, characterized in that: The cooling nozzle group includes at least: a first nozzle assembly covering the upper surface of the forging body; a second nozzle assembly covering the lower surface and bottom corners of the forging body; The third nozzle group targets the side walls and protruding ribs of forgings; A fourth dedicated internal cooling nozzle group for internal holes and groove features of forgings; The cooling medium type, flow rate and pressure of each group of nozzles can be set and adjusted independently.

10. A non-volatile storage medium storing a computer program, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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