A method and system for heat treating irregular metal forgings

Abstract

The application relates to the technical field of metal forging processing, in particular to an irregular metal forging heat treatment method and system. Firstly, temperature compensation subareas are divided according to geometric characteristics, and step-by-step preheating is implemented to establish a uniform basic temperature field; then, the holding time of each subarea is independently regulated in the austenitizing stage, and the full conversion of the structure of thick-wall areas and the grain size control of thin-wall areas are considered; in the quenching process, the strength of each subarea is adjusted based on a preset cooling map, and the cooling parameters are dynamically optimized through real-time feedback; finally, subarea step-by-step tempering is implemented according to the residual stress distribution. Through subarea dynamic temperature management, the heating and cooling uniformity is significantly improved, and the organization difference and thermal stress concentration caused by cross-section mutation are effectively inhibited; through austenitizing control, the microstructure is ensured to be uniform and stable; through a differentiated cooling strategy, the hardenability and deformation resistance are balanced; an intelligent tempering mechanism realizes directional reduction of residual stress, improves the comprehensive mechanical properties and greatly reduces the cracking risk.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal forging processing, in particular to an irregular metal forging heat treatment method and system. BACKGROUND

[0002] The heating and cooling of metal forgings is a core link that determines the final performance. Heating needs to be uniformly and thoroughly burned in a specific temperature range (such as 1100-1250℃ for carbon steel) to improve plasticity and complete austenitization, but overheating (coarse grains), overburning (grain boundary melting) and surface oxidation and decarburization need to be avoided. The cooling process is more critical: the cooling speed directly affects the microstructure transformation and stress distribution. Air cooling, pit cooling or furnace cooling are used for slow cooling to prevent cracking; quenching can achieve rapid hardening, but immediate tempering is required to eliminate brittleness. If the cooling is uneven, it will cause threefold harm: thermal stress due to the difference between the surface and the core contraction, microstructure stress due to the asynchronous phase change, and the superposition of the two, which can easily lead to cracking or deformation of the forging; at the same time, it causes uneven grain size, hardness fluctuation (such as surface martensite and core pearlite), and residual harmful internal stress, which significantly reduces the fatigue life and dimensional stability. Therefore, it is necessary to accurately coordinate the temperature control according to the material properties and forging structure to avoid defect chain reactions.

[0003] In the prior art, due to the shape and size factors of metal forgings, the parts near the edge, small parts and thin-walled parts cool faster, while the corner parts and thick parts cool slower, the grains in the fast cooling zone are small or hard and brittle structures (such as martensite) are formed, and the grains in the slow cooling zone are coarse or soft structures (such as ferrite + pearlite) are formed, resulting in uneven distribution of hardness, strength and toughness inside the forging, the appearance of soft or hard spots, and even cracking, deformation and scrap of the forging, or uneven microstructure and performance, excessive residual stress, etc.

[0004] CONTENT

[0005] The purpose of the present application is to provide an irregular metal forging heat treatment method and system to solve the problems of microstructure and performance differences, residual stress concentration and deformation exceeding the standard caused by heat conduction lag and uneven cooling in the traditional heat treatment process through the synergistic effect of partition temperature field control, multi-modal austenitization regulation, gradient cooling strength adaptation and stress-oriented tempering technology.

[0006] In a first aspect, the embodiments of the present application provide an irregular metal forging heat treatment method, comprising:

[0007] S100, partition gradient preheating, dividing the forging into multiple temperature compensation partitions according to the three-dimensional geometric characteristics of the forging, and implementing stepwise temperature rising preheating on each temperature compensation partition to make the temperature difference between the surface and the core ≤50℃, so as to establish a basic temperature field;

[0008] S200, multi-modal austenitizing, after reaching the austenitizing temperature, using multiple independent temperature control units of different temperature compensation partitions, according to the heat capacity and geometric characteristics of each region, independently adjusting and maintaining the actual holding time of each region at the austenitizing temperature;

[0009] S300, partition controllable strength cooling, quenching and cooling 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, through the cooling nozzle group of multiple temperature compensation partitions that can be independently adjusted, different cooling strengths are applied to different regions of the forged piece;

[0010] S400, stress navigation tempering, according to the residual stress distribution map, partition heating is performed on different temperature compensation partitions, and synchronous global step-down temperature tempering is performed.

[0011] In some embodiments, step S100 includes:

[0012] S110, according to the wall thickness mutation rate of the forged piece three-dimensional model, identifying each thickness gradient ≥ 15 mm / cm geometric transition zone as a temperature compensation partition,

[0013] S120, the first stage is heated at a rate of ≤60℃ / h to 300℃ and held;

[0014] S130, the second stage implements additional isothermal holding of the maximum thickness value mm / 2 minutes for the temperature compensation partition;

[0015] S140, the third stage is heated at a rate of 80-100℃ / h to the austenitizing temperature.

[0016] In some embodiments, step S200 includes:

[0017] S210, for the temperature compensation partition with a cross-sectional thickness greater than the preset value, the heating mode is calculated based on its maximum cross-sectional thickness to ensure sufficient austenitizing of the core;

[0018] S220, for the temperature compensation partition with a cross-sectional thickness less than or equal to the preset value, the heating mode is calculated based on its minimum effective thickness, and an upper limit value is set to prevent excessive grain growth;

[0019] 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 entire region reaches the austenitizing temperature.

[0020] In some embodiments, in step S300, different regions of the forged piece are applied with different cooling strengths, including:

[0021] a. For temperature compensation zones with cross-sectional thickness greater than a preset value, set to high intensity cooling;

[0022] b. For temperature compensation zones with cross-sectional thickness less than or equal to a preset value, set to low-moderate intensity cooling;

[0023] c. For complex internal cavity areas such as inner holes, narrow slots, etc., use high-permeability cooling medium with directional jet for moderate intensity cooling.

[0024] In some embodiments, step S300 further comprises:

[0025] S310, dynamic feedback regulation, during the cooling process, real-time monitoring of the surface temperature change rate of different temperature compensation zones of the forging, according to the deviation of the actual cooling rate and the preset target cooling rate, dynamically adjusting the parameters of the cooling nozzle group corresponding to the temperature compensation zone, so that the actual cooling rate tends to the target value.

[0026] In some embodiments, step S310 comprises:

[0027] S311, real-time acquisition of the monitoring point temperature data of each temperature compensation zone, and calculation of its instantaneous cooling rate;

[0028] S312, comparing the calculated instantaneous cooling rate with the target cooling rate curve of the temperature compensation zone;

[0029] S313, if the measured rate is higher than the target rate, reduce the flow or pressure of the cooling nozzle group responsible for the temperature compensation zone; if the measured rate is lower than the target rate, increase the flow or pressure of the cooling nozzle group responsible for the temperature compensation zone.

[0030] In some embodiments, step S400 comprises:

[0031] S410, heating to the first tempering temperature at a rate of 40-60°C / hour and holding, the holding time is mm / 3 minutes of the maximum cross-sectional dimension of the forging;

[0032] S420, heating to the second tempering temperature at a rate of 30-50°C / hour, and holding for a time of mm / 6 minutes of the maximum cross-sectional dimension of the forging;

[0033] S430, when the temperature exceeds the set threshold, automatically reduce the heating rate by 5-10°C / h and extend the holding time by 20%-30%

[0034] S440, furnace cooling to below 300°C and then air cooling.

[0035] The second aspect of the present application provides an irregular metal forging heat treatment system, comprising:

[0036] a gradient division module, configured to scan a three-dimensional geometric feature of the forging and divide a temperature compensation zone according to the three-dimensional geometric feature of the forging;

[0037] a multi-source array heating module, configured to heat the temperature compensation zone;

[0038] a temperature control module, configured to monitor surface temperature and change rate of a key area of the forging, independently adjust and maintain actual holding time of each area at the austenitizing temperature according to heat capacity and geometric feature of each area, and determine differential cooling intensity applied to different areas of the forging according to geometric feature, material property and a preset cooling intensity map of each area of the forging;

[0039] a cooling nozzle group, configured to apply differential cooling intensity to different areas of the forging.

[0040] In some embodiments, the cooling nozzle group comprises at least the following in spatial distribution:

[0041] a first nozzle group covering an upper surface of a main body of the forging;

[0042] a second nozzle group covering a lower surface and a bottom corner of the main body of the forging;

[0043] a third nozzle group for a side wall and a protruding rib plate of the forging;

[0044] a fourth special internal cooling nozzle group for internal holes and groove features of the forging;

[0045] The cooling medium type, flow rate and pressure of each group of nozzles can be independently set and adjusted.

[0046] The third aspect of the application provides a non-volatile storage medium storing a computer program, which, when executed by a processor, implements the steps of the above heat treatment method.

[0047] The application has the following beneficial effects: for irregular metal forgings, first, temperature compensation zones are divided according to geometric features, and stepwise preheating is implemented to establish a uniform basic temperature field; then, holding time of each zone is independently regulated during the austenitizing stage, taking into account full conversion of the microstructure in thick wall areas and control of grain size in thin wall areas; during the quenching process, the intensity of each zone is adjusted based on a preset cooling map, and cooling parameters are dynamically optimized in real time through feedback; finally, stepwise tempering is implemented for different zones according to residual stress distribution. Through dynamic temperature management of different zones, heating and cooling uniformity is significantly improved, and differences in microstructure and thermal stress concentration caused by sudden changes in cross section are effectively suppressed; through austenitizing control, the microstructure is ensured to be uniform and stable; through differential cooling strategies, hardenability and deformation resistance are balanced; an intelligent tempering mechanism realizes directional reduction of residual stress, improves comprehensive mechanical properties, and significantly reduces the risk of cracking. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 Flow chart for the irregular metal forging heat treatment method in the present application;

[0049] Figure 2 Flow chart for the partition gradient preheating in the present application;

[0050] Figure 3 Flow chart for the multi-modal austenitizing in the present application;

[0051] Figure 4 Flow chart for the dynamic feedback regulation in the present application;

[0052] Figure 5 Flow chart for the stress navigation tempering in the present application;

[0053] Figure 6 Module chart for the irregular metal forging heat treatment system in the present application. DETAILED DESCRIPTION

[0054] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. 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.

[0055] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0056] In the embodiments of the present disclosure, it should be understood that the disclosed apparatus and method can also be implemented in other manners. The embodiments described above are merely exemplary. For example, the flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architectures, functions and operation of the apparatus, method and computer program product according to the embodiments of the present disclosure. In this regard, each block in the flowcharts and block diagrams can represent a module, a program segment or a part of code, which contains one or more executable instructions for implementing the specified logic function. It should also be noted that, in some alternative implementations, the functions noted in the blocks can occur in a different order from that noted in the accompanying drawings. For example, two consecutive blocks can actually be executed in parallel, and sometimes they can be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and the combination of blocks in the block diagrams and / or flowcharts, can be implemented by a dedicated hardware-based system for implementing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0057] In addition, the functional modules in the various embodiments of the present disclosure can be integrated together to form a separate part, or each module can exist independently, or two or more modules can be integrated to form a separate part.

[0058] 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 solutions of the present disclosure can be embodied in the form of a software product, and the computer software product is stored in a storage medium, and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present disclosure. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0059] The irregular metal forgings face several problems in the heat treatment process. Due to the shape and size factors of the metal forgings, the components close to the edge, the small components and the thin-walled components are cooled faster, while the corner parts and the thick parts are cooled slower. The grains in the fast-cooling zone are small or hard and brittle (such as martensite), and the grains in the slow-cooling zone are coarse or soft (such as ferrite + pearlite), resulting in uneven distribution of hardness, strength and toughness inside the forging, and the appearance of soft spots or hard spots, even the cracking of the forging, deformation and scrap, or uneven organization and performance, and excessive residual stress

[0060] The traditional forging heat treatment adopts a whole uniform heating and cooling mode. For irregular components with a wall thickness mutation rate of ≥15 mm / cm, the maximum temperature difference between the surface and the center during the heating stage often exceeds 150℃, the actual holding time of the thin-walled area during the austenitizing holding stage exceeds that of the thick-walled area by 40%-60%, and the cooling speed of the thin-walled area during the quenching cooling stage can be 2.5 times or more than that of the thick-walled area. Such thermal process non-uniformity leads to a microstructure difference of >30%, a hardness fluctuation range of >5HRC, and a residual stress peak value exceeding 70% of the material yield strength. The prior art attempts to improve it by local shielding or zoned spraying, but due to the lack of a dynamic coupling model of geometric features and thermal parameters, the actual control precision is insufficient, and the temperature difference control error is still large.

[0061] Therefore, the first aspect of the present application provides an irregular metal forging heat treatment method and system.

[0062] Embodiment one

[0063] Referring to Figure 1 The first aspect of the embodiment of the present application provides an irregular metal forging heat treatment method, comprising:

[0064] S100, gradient preheating, dividing the forging into multiple temperature compensation zones according to the three-dimensional geometric features of the forging, and implementing stepwise temperature rising preheating on each temperature compensation zone to make the temperature difference between the surface and the center ≤50℃, so as to establish a basic temperature field;

[0065] Referring to Figure 2 In some embodiments, step S100 comprises:

[0066] S110, identification according to the wall thickness mutation rate of the three-dimensional model of the forging, dividing each geometric transition zone with a thickness gradient of ≥15 mm / cm into a temperature compensation zone; at the same time, a curvature radius analysis method is used to assist the thickness gradient identification, and when the curvature radius R of the curved surface is <50 mm and the thickness difference between adjacent regions is ≥40 mm, the transition zone is forcibly divided into a mutation compensation zone.

[0067] S120, the first stage is heated to 300℃ at a rate of ≤60℃ / h and held;

[0068] ​After heating at a rate of 55±5℃ / h to 300℃ and holding for 2.5-3 hours to eliminate more than 60% of the machining stress, the internal temperature is collected every 15 minutes, and if the difference between the internal temperature and the surface temperature at the end of the holding at 300℃ is >18℃, the holding time is extended until the temperature difference is ≤12℃

[0069] S130, the second stage implements an additional isothermal holding of the maximum thickness value mm / 2 minutes for the temperature compensation partition;

[0070] For a partition with a maximum thickness ≥100mm, the additional holding time is calculated as T=(300-100) / 2) minutes (unit: mm), for example, a 300mm thick zone is held for 150 minutes to converge the cross-section temperature difference to within 35℃, and at the same time, an additional thickness value mm / 4 minutes is applied to the sudden change compensation partition (such as the connection between the boss and the base) to compensate for the time. The unit is mm), for example, a 300mm thick zone is held for 150 minutes to converge the cross-section temperature difference to within 35℃, and at the same time, an additional thickness value mm / 4 minutes is applied to the sudden change compensation partition (such as the connection between the boss and the base) to compensate for the time.

[0071] S140, the third stage is heated to the austenitizing temperature at a rate of 80-100℃ / h.

[0072] The rate of increase is 90±10℃ / h to the austenitizing temperature (such as 860℃, which is determined according to the material), and the temperature difference between the surface and the interior at the end of the heating period is ≤45℃, and at the same time, the heating is paused at 500℃ and 700℃ for 15 minutes each for temperature equalization.

[0073] S200, multi-modal austenitizing, after reaching the austenitizing temperature, the actual holding time of each region at the austenitizing temperature is independently adjusted and maintained using multiple independent temperature control units for different temperature compensation partitions according to the thermal capacity and geometric characteristics of each region; the PID-fuzzy composite control is used to establish the austenitizing temperature field to enhance the robustness, adaptability and control accuracy of the system.

[0074] Referring to Figure 3 In some embodiments, step S200 includes:

[0075] S210, for a temperature compensation partition with a cross-sectional thickness greater than a preset value, the heating mode is calculated based on its maximum cross-sectional thickness to ensure sufficient austenitization of the core;

[0076] In this embodiment, the preset thickness threshold is 100mm, and for a thick-walled zone with a thickness >100mm, when the distance from the surface to the depth of Ac3+10℃ is reached, the effective holding time is started to be calculated.

[0077] S220, for a temperature compensation partition 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 value is set to prevent excessive grain growth; wherein the grain growth control adopts a double constraint mechanism: the upper limit of the heating time for a thin-walled zone​​ ≤ (0.06 x ) min, and the upper temperature limit is not more than Ac3+40℃.

[0078] 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.

[0079] 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%.

[0080] 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 of each region of the forged piece and the preset cooling strength map, a plurality of cooling nozzles groups which can be independently adjusted are used to apply different cooling strength to different regions of the forged piece; wherein the cooling strength map is a cooling rate temperature change curve which is pre-planned according to the material of the metal forged piece and the preset strength.

[0081] 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, the angle change range is ±15°-±45°, so as to realize the effect of uniform cooling of each position of the irregular forged piece.

[0082] In some embodiments, in step S300, different cooling strength is applied to different regions of the forged piece, including:

[0083] 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.

[0084] 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.

[0085] c. For complex internal cavity areas such as inner holes and narrow grooves, medium-intensity cooling is performed using directional jetting of high-permeability cooling medium. High-permeability medium containing nano ceramic particles is used in the inner hole and narrow groove area. The jetting angle is controlled within ± 15°, and the cooling rate is maintained at 20 ± 2 ℃ / s. The cooling medium temperature is maintained at 30 ± 2 ℃, and the concentration fluctuation is less than 1.5%.

[0086] In some embodiments, step S300 further comprises:

[0087] S310, dynamic feedback regulation, during the cooling process, the surface temperature change rate of different temperature compensation partitions of the forged piece is monitored in real time, and according to the deviation between the actual cooling rate and the preset target cooling rate, the parameters of the cooling nozzle group corresponding to the temperature compensation partition are dynamically adjusted, so that the actual cooling rate tends to the target value.

[0088] Referring to Figure 4 Wherein, step S310 comprises:

[0089] S311, real-time acquisition of monitoring point temperature data of each temperature compensation partition, and calculation of its instantaneous cooling rate;

[0090] Wherein, the instantaneous cooling rate V is calculated by five-point central difference method:

[0091]

[0092] Wherein, the time step =0.2s, and the temperature data is derived from the thermocouple array arranged according to isotherms in each temperature compensation partition, with a point density of:

[0093] Region with thickness ≥100 mm: 1 temperature measuring point is arranged every 50 mm×50 mm area;

[0094] Region with thickness <100 mm: 1 temperature measuring point is arranged every 80 mm×80 mm area; thermocouple response time ≤0.1s, temperature measurement accuracy ±0.8℃.

[0095] S312, comparing the calculated instantaneous cooling rate with the target cooling rate curve of the temperature compensation partition;

[0096] The rate comparison link sets a dynamic dead zone threshold:

[0097] When the temperature >500℃ (austenite stable zone), the dead zone range is ±4 / s;

[0098] When 300℃≤temperature≤500℃ (pearlite transformation zone), the dead zone is reduced to ±2 / s;

[0099] When temperature < 300℃ (martensite transformation zone), dead zone expands to ±5 / s.

[0100] The comparator performs deviation analysis every 0.25 seconds, and triggers the adjustment instruction when the continuous 3 samples exceed the dead zone, avoiding actuator oscillation.

[0101] S313, if the measured rate is higher than the target rate, reduce the flow or pressure of the cooling nozzle group responsible for the temperature compensation partition; if the measured rate is lower than the target rate, increase the flow or pressure of the cooling nozzle group responsible for the temperature compensation partition.

[0102] The execution control link adopts a two-stage linkage mechanism:

[0103] Primary regulation: adjust the cooling medium flow through proportional integral valve, flow change slope ;

[0104] When the cooling rate needs to be reduced, reduce the flow by 3.5% per deviation 1 / s; when the cooling rate needs to be increased, the flow increase limit is 120% of the baseline value.

[0105] Secondary regulation: when the flow regulation reaches the limit and still does not meet the requirements, start the pressure compensation system:

[0106] Boost mode: pressure lifting gradient = 0.05 MPa / (℃ / s); pressure reduction mode: the minimum pressure can be reduced to 0.15 MPa.

[0107] Among them, the actuator response time is <0.3 seconds, the flow control linearity is ≥0.97, and through the double-stage regulation, the cooling rate tracking lag is effectively reduced, and the target cooling rate achievement rate is improved.

[0108] S400, stress navigation tempering, according to the residual stress distribution map, different temperature compensation partitions are heated, and global step-down tempering is carried out at the same time. Among them, the residual stress is detected by X-ray diffraction, and based on the real-time stress detection data, the tempering temperature curve is dynamically adjusted to generate a compensation strategy.

[0109] Referring to Figure 5 , in some embodiments, step S400 includes:

[0110] S410, the temperature is raised to the first tempering temperature at a rate of 40-60°C / hour and is kept for a duration of mm / 3 minutes for the maximum cross-sectional dimension of the forging;

[0111] 300℃→400 interval: 60±5 / h to accelerate through the hydrogen embrittlement sensitive zone, 400°C→ target temperature zone: decrease to 45±5°C / h to avoid the temper embrittlement sensitive zone;

[0112] holding time in minutes = max cross section dimension of the forging / 6 calculated as T1 = max cross section dimension of the forging / 3 minutes, for example = 300mm then holding for 100 minutes, = 450mm then holding for 150 minutes, so as to sufficiently eliminate residual stress and hardness uniformity deviation.

[0113] S420, increase the temperature to the second tempering temperature at a rate of 30-50°C / hour, and the holding time is max cross section dimension of the forging mm / 6 minutes;

[0114] continue to increase the temperature to the second tempering temperature at a rate of 40±2 / h, set to the Ac1-70°C to Ac1-50°C zone, and insert a 30-minute uniformity platform at 550°C, wherein the holding time T2 = / 6 minutes, for example = 300mm then holding for 50 minutes; wherein, for materials with hydrogen content > 2.5 ppm, an additional 120-minute holding time is added in the 350-450 zone, so as to reduce the spheroidization rate of grain boundary carbides.

[0115] S430, when the temperature exceeds the set threshold, automatically reduce the heating rate by 5-10 / h and extend the holding time by 20%-30%

[0116] Specifically, the over-temperature protection mechanism adopts a three-level response strategy:

[0117] When the over-temperature amplitude 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%;

[0118] When the over-temperature amplitude is > 25°C, inert gas is sprayed to forcibly cool, and an audible and light alarm is triggered and the process is paused;

[0119] When the over-temperature amplitude is > 40°C, the water cooling coil system is urgently started, the process is terminated, and fault diagnosis is performed.

[0120] S440, the furnace is cooled to below 300°C and is discharged for air cooling.

[0121] ​The furnace cooling process implements phase change driven cooling: high temperature section (tempering temperature - 500 DEG C), cooling rate is less than or equal to 35 DEG C / h; medium temperature section (500-400 DEG C), the cooling rate is less than or equal to 25 DEG C / h to avoid the tempering brittle zone; low temperature section (400-300 DEG C), maintain less than or equal to 28 DEG C / h. When the temperature drops to 300 DEG C ± 10 DEG C, transfer to static air cooling, and immediately after the furnace is taken out, the anti-oxidation treatment is carried out.

[0122] For irregular metal forgings, first, the temperature compensation partition is divided according to the geometric characteristics, and the step preheating is implemented to establish a uniform basic temperature field; then the holding time of each partition is independently controlled in the austenitizing stage, taking into account the full conversion of the thick wall zone and the grain size control of the thin wall zone; the quenching process is based on the preset cooling map for partition strength adjustment, and the cooling parameters are dynamically optimized through real-time feedback; finally, the partition step tempering is implemented according to the residual stress distribution. Through the dynamic temperature management of the partition, the heating and cooling uniformity is significantly improved, and the organization difference and thermal stress concentration caused by the sudden change of the cross section are effectively inhibited; through the austenitizing control, the microstructure is uniform and stable; through the differential cooling strategy, the hardenability and deformation resistance are balanced; the intelligent tempering mechanism realizes the directional reduction of residual stress, which improves the comprehensive mechanical properties and greatly reduces the cracking risk.

[0123] Embodiment two

[0124] Reference Figure 6 The second aspect of the present application provides an irregular metal forging heat treatment system, comprising:

[0125] A gradient division module is used for scanning the three-dimensional geometric characteristics of the forging and dividing temperature compensation partitions according to the three-dimensional geometric characteristics of the forging; the module includes a file acquisition unit for determining the size according to the drawing and a three-dimensional entity scanning unit;

[0126] A multi-source array heating module is used for heating the temperature compensation partitions; the module includes infrared heating components and laser auxiliary heating components arranged in multiple positions;

[0127] A temperature control module is used for monitoring the surface temperature and change rate of the key areas of the forging, independently adjusting and maintaining the actual holding time of each area at the austenitizing temperature according to the heat capacity and geometric characteristics of each area, and determining the differential cooling intensity applied to different areas of the forging according to the geometric characteristics, material properties and preset cooling intensity map of each area of the forging; the module includes a thermocouple array arranged at different positions of the forging and temperature sensors distributed at different positions;

[0128] A cooling nozzle group is used for applying differential cooling intensity to different areas of the forging.

[0129] In some embodiments, the cooling nozzle groups are spatially distributed at least including: a first nozzle group covering the upper surface of the forging body; a second nozzle group covering the lower surface and bottom corner of the forging body; a third nozzle group for the side wall and protruding rib plate of the forging; a fourth dedicated internal cooling nozzle group for the internal hole, slot features of the forging;

[0130] The cooling medium type, flow rate, and pressure of each group of nozzles can be independently set and adjusted.

[0131] Embodiment three

[0132] The third aspect of the present application provides a non-volatile storage medium storing a computer program, which, when executed by a processor, implements the steps of the heat treatment method described above.

[0133] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0134] It is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and 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 regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims.

Claims

1. A heat treatment method for irregular metal forgings, characterized in that, include: S100, zoned gradient preheating, divides the forging into multiple temperature compensation zones based on its three-dimensional geometric characteristics. Each temperature compensation zone undergoes stepped preheating to ensure the surface-to-core temperature difference is ≤50℃, thus establishing a basic temperature field. Specifically, this includes… S110, based on the wall thickness abrupt change rate identification of the three-dimensional model of the forging, geometric transition zones with each thickness gradient ≥15mm / cm are designated as temperature compensation zones; simultaneously, the radius of curvature analysis method is used to assist in thickness gradient identification, and when the surface curvature radius R <50mm and the thickness difference Δδ between adjacent regions ≥40mm, it is forcibly classified as an abrupt change compensation zone. S120, first stage, heat up to 300℃ at a rate of ≤60℃ / h and hold for 2.5-3 hours. At the same time, collect the internal temperature every 15 minutes. If the difference between the internal temperature and the surface temperature is >18℃ when the holding time at 300℃ ends, extend the holding time until the temperature difference is ≤12℃. S130, Second Stage: Additional isothermal maintenance is implemented for temperature compensation zones. For zones with a maximum thickness ≥100mm, the additional insulation time is calculated as T=( The calculation takes 2 minutes, and an additional thickness value of mm / 4 minutes is applied to the abrupt change compensation zone for compensation. This is the maximum thickness value, in mm. S140, the third stage, is heated to the austenitizing temperature at a rate of 80-100℃ / h. At the end of the heating period, the temperature difference between the surface and the interior is ≤45℃. At the same time, the heating is paused for 15 minutes at 500℃ and 700℃ respectively to achieve temperature equalization. S200, multimodal austenitization, after reaching the austenitization temperature, utilizes multiple independent temperature control units in different temperature compensation zones to independently adjust and maintain the actual holding time of each zone at the austenitization temperature based on the heat capacity and geometric characteristics of each zone. Specifically, this includes... S210, for temperature compensation zones with a cross-sectional thickness greater than a preset value, the heating mode is calculated based on the maximum cross-sectional thickness. When the thick-walled zone is far from the surface... When the temperature at depth reaches Ac3+10℃, the effective insulation time is calculated. S220: For temperature-compensated zones with a cross-sectional thickness less than or equal to a preset value, the heating mode is calculated based on its minimum thickness value, and an upper limit is set to prevent excessive grain growth. The upper limit for heating time in thin-walled regions is also specified. ≤(0.06× (minutes), and the upper limit of the temperature does not exceed Ac3+40℃. This is the minimum thickness value, in mm. S230 employs a pulsed rapid heating mode for temperature compensation zones with a cross-sectional thickness greater than the preset value, and a slow heating mode for temperature compensation zones with a cross-sectional thickness less than or equal to the preset value, until the entire region reaches the austenitizing temperature. The pulsed rapid heating mode uses an instantaneous heating rate of 10-15℃ / min, with each pulse lasting ≤3 minutes and a pulse interval ≥5 minutes; the slow heating mode has a heating rate ≤80℃ / h. S300, a zoned controllable intensity cooling system, is used for quenching and cooling austenitized forgings. During the cooling process, based on the heat capacity, geometric characteristics, and preset cooling intensity map of each region of the forging, differentiated cooling intensities are applied to different regions of the forging through multiple independently adjustable temperature-compensated cooling nozzle groups. Specifically, this includes... S310, for temperature compensation zones with a cross-sectional thickness greater than the preset value, is set to high-intensity cooling, with a cooling rate ≥45℃ / s and a nozzle pressure setting of 0.8-1.2MPa. S320, for temperature compensation zones with a cross-sectional thickness less than or equal to a preset value, is set to medium-low intensity cooling, with a cooling rate of 15-25℃ / s and a pressure reduction to 0.3-0.5MPa. S330 employs a directional jet of highly permeable cooling medium for medium-intensity cooling in complex internal cavity areas such as inner holes and narrow grooves. The jet angle is controlled within ±15°, the cooling rate is maintained at 20±2℃ / s, the cooling medium temperature is kept at 30±2℃, and the concentration fluctuation is <1.5%. S400, stress-guided tempering, involves zoned heating of different temperature compensation zones based on the residual stress distribution map, while simultaneously performing full-area stepped cooling tempering. Specifically, this includes... S410 is heated to the first tempering temperature at a rate of 40-60°C / hour and held at that temperature for 3 minutes, with the holding time being the maximum cross-sectional thickness of the forging in mm. Specifically, in the 300°C → 400°C range, the heating rate is 60±5°C / h; in the 400°C → target temperature range, the heating rate is reduced to 45±5°C / h. S420 is heated to the second tempering temperature at a rate of 30-50°C / hour. The second tempering temperature is in the range of Ac1-70°C to Ac1-50°C. The holding time is 6 minutes per mm of the maximum thickness of the forging cross-section. The sample is then immersed in a 30-minute temperature equalization plateau at 550°C. When the S430 detects that the 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, then air cooled after exiting the furnace.

2. The heat treatment method for irregular metal forgings according to claim 1, characterized in that, Step S300 also includes: S310 features dynamic feedback control. During the cooling process, it monitors the surface temperature change rate of different temperature compensation zones of the forging in real time. Based on the deviation between the monitored actual cooling rate and the preset target cooling rate, it dynamically adjusts the parameters of the cooling nozzle group in the corresponding temperature compensation zone to make the actual cooling rate approach the target value.

3. The heat treatment method for irregular metal forgings according to claim 2, characterized in that, Step S310 includes: S311 collects temperature data from monitoring points in each temperature compensation zone in real time and calculates its instantaneous cooling rate. S312, compare the calculated instantaneous cooling rate with the target cooling rate curve of the temperature compensation zone; S313, if the measured rate is higher than the target rate, reduce the flow rate or pressure of the cooling nozzle group responsible for the temperature compensation zone; if the measured rate is lower than the target rate, increase the flow rate or pressure of the cooling nozzle group responsible for the temperature compensation zone.

4. A heat treatment system for irregular metal forgings, used to implement the heat treatment method for irregular metal forgings according to any one of claims 1-3, characterized in that, include: The gradient partitioning module is used to scan the three-dimensional geometric features of the forging and divide the temperature compensation zone according to the three-dimensional geometric features of the forging. Multi-source array heating module, used for heating temperature-compensated zones; The 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 according to the heat capacity and geometric characteristics of each area, and determine the differentiated cooling intensity applied to different areas of the forging according to the geometric characteristics, material properties and preset cooling intensity spectrum of each area of ​​the forging. Cooling nozzle assembly is used to apply differentiated cooling intensities to different areas of the forging.

5. The heat treatment system for irregular metal forgings according to claim 4, characterized in that, The cooling nozzle assembly includes at least the following spatially distributed components: The first nozzle assembly covers the upper surface of the forging body; A second nozzle assembly covering the lower surface and bottom corners of the forging body; A third nozzle assembly for the sidewalls and protruding ribs of forgings; A fourth dedicated internal cooling nozzle group is designed for the internal holes and grooves of forgings; the cooling medium type, flow rate, and pressure of each nozzle group can be set and adjusted independently.

6. A non-volatile storage medium storing a computer program, characterized in that, When the program is executed by the processor, it implements the steps of the method according to any one of claims 1-3.

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