CN114774652A - 17CrNiMo6 material preliminary heat treatment method - Google Patents
17CrNiMo6 material preliminary heat treatment method Download PDFInfo
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- CN114774652A CN114774652A CN202210475008.8A CN202210475008A CN114774652A CN 114774652 A CN114774652 A CN 114774652A CN 202210475008 A CN202210475008 A CN 202210475008A CN 114774652 A CN114774652 A CN 114774652A
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- 238000010438 heat treatment Methods 0.000 title claims abstract description 184
- 239000000463 material Substances 0.000 title claims abstract description 87
- 238000000034 method Methods 0.000 title claims abstract description 57
- 238000001816 cooling Methods 0.000 claims abstract description 49
- 238000004321 preservation Methods 0.000 claims description 36
- 230000008569 process Effects 0.000 claims description 27
- 238000003756 stirring Methods 0.000 claims description 6
- 238000004513 sizing Methods 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 21
- 230000009286 beneficial effect Effects 0.000 abstract description 5
- 239000007769 metal material Substances 0.000 abstract description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical group C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 20
- 239000003345 natural gas Substances 0.000 description 10
- 229910000831 Steel Inorganic materials 0.000 description 8
- 230000008901 benefit Effects 0.000 description 8
- 239000010959 steel Substances 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 229910001563 bainite Inorganic materials 0.000 description 6
- 230000008859 change Effects 0.000 description 6
- 230000006872 improvement Effects 0.000 description 6
- 238000005520 cutting process Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 238000005242 forging Methods 0.000 description 4
- 229910001562 pearlite Inorganic materials 0.000 description 4
- 238000005496 tempering Methods 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- 229910001339 C alloy Inorganic materials 0.000 description 2
- 238000005255 carburizing Methods 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- -1 and meanwhile Inorganic materials 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
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- Crystallography & Structural Chemistry (AREA)
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- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatments In General, Especially Conveying And Cooling (AREA)
Abstract
The invention relates to the technical field of metal material heat treatment, and discloses a 17CrNiMo6 material preliminary heat treatment method, which comprises the steps of heating a 17CrNiMo6 material, drawing the material out along with heat treatment equipment for cooling, returning the part into the heat treatment equipment again when the part is cooled to a certain temperature range, carrying out temperature equalization on the part by utilizing the temperature difference between the inside and the outside of the part, drawing the part out along with the heat treatment equipment again for cooling, returning the part into the equipment again for temperature equalization after cooling, repeatedly carrying out cooling and temperature equalization for multiple times, controlling the temperature of the 17CrNiMo6 material to be uniformly changed and the internal structure to be uniformly changed, heating the 17CrNiMo6 material again to a certain temperature range after cooling and temperature equalization for multiple times, preserving the temperature for a certain time, and finally taking out the 17CrNiMo6 material for natural cooling in the air. The invention has the beneficial effects of reducing the technical difficulty of heat treatment of the 17CrNiMo6 material, saving the production cost of the 17CrNiMo6 material and improving the heat treatment efficiency and quality of the 17CrNiMo6 material.
Description
Technical Field
The invention relates to the technical field of heat treatment of metal materials, in particular to a 17CrNiMo6 material preheating treatment method.
Background
At present, the steel grade adopted by key parts of a high-power fan and an internal combustion engine, such as gears, input/output shafts and the like, is 17CrNiMo6, belongs to low-carbon alloy carburizing steel, and is finally formed by forging and machining, and the quality of heat treatment after forging is important for subsequent cutting processing. The normalized structure of the forging is required to be ferrite and pearlite, the hardness value is 160-200 HBW, and the grain size is greater than or equal to 5 grade. The 17CrNiMo6 steel has good hardenability, and after the preliminary heat treatment is carried out by adopting a conventional normalizing and tempering mode, a plurality of quality defects exist, for example, bainite exists in the structure of the 17CrNiMo6 steel, the hardness value of the 17CrNiMo6 steel is higher than 220HBW, so that the difference of the structure and the hardness between different parts or different positions of the same part is larger, the cutting processing performance is deteriorated, the heat treatment deformation is increased, the precision grade and the performance of the 17CrNiMo6 steel are reduced, and the production specification requirement of the 17CrNiMo6 cannot be met.
In order to meet the technical requirements of 17CrNiMo6 on the preliminary heat treatment, in the prior preliminary heat treatment process of the 17CrNiMo6 material, an isothermal normalizing process is adopted in an isothermal normalizing line (equipment) to carry out 17CrNiMo6 preliminary heat treatment, although the quality of the 17CrNiMo6 after the preliminary heat treatment can be improved to a certain extent, so that the treated 17CrNiMo6 meets the quality requirements, the problems also exist, such as high manufacturing cost of the isothermal normalizing production line, large floor area and difficult control of process setting parameters, and particularly difficult accurate control of a charging mode, a quick cooling mode and quick cooling time in an intermediate cooling stage, the production line is not configured in a general factory, and great difficulty is brought to the preliminary heat treatment of the 17CrNiMo6 material.
Disclosure of Invention
The invention aims to provide a 17CrNiMo6 material preliminary heat treatment method to reduce the technical difficulty of carrying out preliminary heat treatment on a 17CrNiMo6 material.
In order to achieve the purpose, the invention adopts the following technical scheme: a preparation heat treatment method of a 17CrNiMo6 material comprises the following steps:
s1, preparing a 17CrNiMo6 material to be subjected to heat treatment and heat treatment equipment, debugging parameters of the heat treatment equipment, mounting a part to be processed on the heat treatment equipment, and controlling the single treatment capacity of the part not to be larger than the maximum loading capacity of the heat treatment equipment;
step S2, heating the temperature in the heat treatment equipment to a first preset temperature range at a first preset heating speed, carrying out heat preservation for a preset time after the temperature is heated, stopping heating the equipment after the heat preservation time reaches the process heat preservation time, closing a heating source of the heat treatment equipment, completely opening a switch door of the heat treatment equipment, taking out the heated parts from the heat treatment equipment, and exposing the parts in the air for cooling;
step S3, when the part is cooled to a second preset temperature range, returning the part to the heat treatment equipment for cooling and temperature equalization for multiple times, after the temperature equalization is finished, cooling the part to the second preset temperature range again, returning the part to the heat treatment equipment, closing a switch door to cool the part to a third preset temperature range along with the heat treatment equipment, then heating the temperature in the heat treatment equipment to a fourth preset temperature range at a second preset speed, and carrying out heat preservation for a fixed time;
and step S4, stopping heating the heat treatment equipment after the process heat preservation time is reached, closing a heating source of the heat treatment equipment, cooling the part along with the heat treatment equipment to a fifth preset temperature range, taking the part out of the heat treatment equipment, and exposing the part in air for cooling until the surface temperature of the part is consistent with the room temperature.
The principle and the advantages of the scheme are as follows: in practical application, an isothermal normalizing production line is not needed, conventional heat treatment equipment is adopted to perform heat treatment operation, parts made of the 17CrNiMo6 material are heated in the equipment to a preset temperature and then are subjected to heat preservation, the heat preservation time is dynamically adjusted according to the thickness of the parts, the heating effect on the parts is guaranteed, accordingly, expected structural change occurs in the 17CrNiMo6 material, then the parts are naturally cooled, accordingly, the transformation of ferrite and pearlite is guaranteed to be uniformly completed in the material, the parts are repeatedly placed in the heat treatment equipment, the parts are subjected to temperature equalization and cooling for multiple times by using waste heat in the equipment, accordingly, the internal structure of the parts is controlled to be uniformly and regularly changed, finally, the parts are heated to the preset temperature again after temperature equalization is completed, heat preservation is performed for a period of time, and finally the parts are taken out to be naturally cooled, so that the heat treatment of the 17CrNiMo6 material can be completed, the 17CrNiMo6 material meeting the production technical requirements is obtained, and the grain size and the hardness of the 17CrNiMo6 material meet the requirements. Compared with the prior art, the method has the advantages that the defects that a bainite structure is generated in a conventional normalizing and tempering heat treatment mode and cutting processing is not facilitated are overcome, an isothermal normalizing production line is not needed, the occupied area of the production line is reduced, the technical difficulty of heat treatment is reduced, the method can be completed only by carrying out technical improvement on the conventional production line, and the production cost is effectively saved.
Preferably, as a modification, the heat treatment apparatus is a car-type furnace.
Has the beneficial effects that: the conventional trolley furnace is adopted as heat treatment equipment to carry out the preliminary heat treatment on the 17CrNiMo6 material, so that the heating work on the 17CrNiMo6 material can be smoothly completed, and the equipment is also convenient for large-area popularization of the preliminary heat treatment method in various factories, thereby improving the overall efficiency and quality of the preliminary heat treatment on the 17CrNiMo6 material and further improving the economic benefit of the factories.
Preferably, as an improvement, the debugging equipment parameters are that the trolley surface is adjusted, the part is isolated from the furnace bottom plate by using a sizing block with the height of more than or equal to 100mm, the distance between adjacent parts is not less than 30mm, and the charging temperature of the part is not more than 500 ℃.
Has the beneficial effects that: by debugging the equipment, the equipment can enter the optimal working state of the 17CrNiMo6 material preliminary heat treatment, so that the efficiency and the quality of the 17CrNiMo6 material preliminary heat treatment are improved, and finally, the 17CrNiMo6 material with the grain size and the hardness meeting the industrial production requirements is obtained.
Preferably, as a modification, a circulation fan is further provided inside the heat treatment apparatus, and the circulation fan is used for stirring heat in the apparatus during heating and heat preservation of the parts in the heat treatment apparatus.
Has the advantages that: through increasing circulating fan device in the heat treatment equipment inside, make the fan work during heat treatment equipment heating and part heat preservation, provide wind-force and blow the stirring to the inside heat of heat treatment equipment to make the inside heat of heat treatment equipment more even, be convenient for carry out stable heating and heat preservation to 17CrNiMo6 material, thereby improve the preliminary heat treatment quality of 17CrNiMo6 material.
Preferably, as a modification, the temperature equalization is that the part is placed in the heat treatment apparatus to exchange heat with heat inside the heat treatment apparatus.
Has the beneficial effects that: through the steps, the temperature difference between the inside and the outside of the part can be reduced, the temperature change is more uniform, the structure is uniformly changed, the generation of non-equilibrium structures is prevented, and the heat treatment quality of the 17CrNiMo6 material is guaranteed.
Preferably, as an improvement, during the temperature equalization, the heating of the heat treatment equipment is stopped and the opening and closing door of the heat treatment equipment is closed.
Has the advantages that: in order to ensure the temperature equalization effect on the 17CrNiMo6 material, the heating of the heat treatment equipment is stopped, the waste of energy sources can be reduced, the temperature equalization process is more natural, meanwhile, a switch door is closed, the loss caused by heat exchange between heat in the equipment and outside air is avoided, the temperature equalization effect on the 17CrNiMo6 material can be further improved, and finally, the preheating treatment effect and the quality of the 17CrNiMo6 material are improved.
Preferably, as an improvement, the temperature equalization times are not more than 5, and each temperature equalization is completed according to the same technical requirements.
Has the advantages that: the 17CrNiMo6 material is subjected to temperature equalization for no more than 5 times, so that the adverse structures of bainite and the like generated by the 17CrNiMo6 material at too high cooling speed due to too many temperature equalization times are avoided, and the final heat treatment quality is influenced.
Preferably, as an improvement, the time for temperature equalization is dynamically adjusted according to the single throughput of the part.
Has the advantages that: if the single treatment capacity of the 17CrNiMo6 material is too large, the change rate influenced by the temperature is reduced, so that the temperature equalizing time is dynamically adjusted according to the single treatment capacity of the part, and the requirement of the temperature change of the 17CrNiMo6 material can be met to the greatest extent, so that the effect of the preliminary heat treatment on the 17CrNiMo6 material is better, and the requirement of industrial quality is met.
Preferably, as a modification, the part is exposed to air for cooling, and the part is placed in air for natural cooling, during which no other cooling auxiliary equipment is used.
Has the advantages that: actual tests show that when the 17CrNiMo6 material is cooled, the structure change rule of the 17CrNiMo6 material can be ensured to the maximum extent by a natural cooling mode, so that the heat treatment quality is ensured, and although the cooling speed can be increased by other auxiliary equipment such as a fan, the cooling speed is too high, the temperature cannot be controlled, unfavorable structures such as bainite can be easily generated, and the quality cannot be controlled.
Preferably, as an improvement, the temperature of the surface of the part is measured with an infrared thermometer when the part is cooled to within the second predetermined temperature range.
Has the beneficial effects that: although the part is cooled, the actual real temperature is very high, and the temperature cannot be measured by touching, a conventional thermometer and the like, so that the temperature is measured by adopting an infrared thermometer in the link, and the accuracy of a temperature measurement result and the safety of measurement equipment can be ensured.
Drawings
FIG. 1 is a schematic flow chart of a first embodiment of a 17CrNiMo6 material preheat treatment method of the invention.
FIG. 2 is a schematic diagram of the temperature time variation of the first embodiment of the preliminary heat treatment method for 17CrNiMo6 material of the invention.
Detailed Description
The following is further detailed by way of specific embodiments:
the first embodiment is as follows:
the embodiment is basically as shown in the attached figure 1: a preparation heat treatment method of a 17CrNiMo6 material comprises the following steps:
s1, preparing a 17CrNiMo6 material to be subjected to heat treatment and heat treatment equipment, debugging parameters of the heat treatment equipment, mounting a part to be processed on the heat treatment equipment, and controlling the single treatment capacity of the part not to be larger than the maximum loading capacity of the heat treatment equipment;
step S2, heating the temperature in the heat treatment equipment to a first preset temperature range at a first preset heating speed, carrying out heat preservation for a preset time after the temperature is heated, stopping heating the equipment after the heat preservation time reaches the process heat preservation time, closing a heating source of the heat treatment equipment, completely opening a switch door of the heat treatment equipment, taking out the heated parts from the heat treatment equipment, and exposing the parts in the air for cooling;
step S3, when the part is cooled to the second preset temperature range, the part is returned to the heat treatment equipment for cooling and temperature equalization for multiple times, after the temperature equalization is finished, the part is cooled to the second preset temperature range again, then the part is returned to the heat treatment equipment, the switch door is closed to enable the part to be cooled to the third preset temperature range along with the heat treatment equipment, then the temperature in the heat treatment equipment is increased to the fourth preset temperature range at the second preset speed, and heat preservation is carried out for a fixed time;
and step S4, stopping heating the heat treatment equipment after the process heat preservation time is reached, closing a heating source of the heat treatment equipment, cooling the part along with the heat treatment equipment to a fifth preset temperature range, taking the part out of the heat treatment equipment, and exposing the part in air for cooling until the surface temperature of the part is consistent with the room temperature.
Specifically, in step S1, the selected heat treatment equipment is a trolley furnace which is conventional in industry, before 17CrNiMo6 material preliminary heat treatment is carried out, the trolley surface is adjusted to isolate the parts from the furnace bottom plate by using a sizing block with the height of more than or equal to 100mm, the total amount of single preliminary heat treatment of the parts of the 17CrNiMo6 material is not more than the maximum loading amount of the trolley furnace, when the parts are placed, the distance between adjacent parts is set to be not less than 30mm, and the charging temperature of the parts is not more than 500 ℃.
Specifically, in step S2, when the temperature in the heat treatment equipment is raised to the first preset temperature range at the first preset heating speed, the range of the first preset heating speed is set within 200 ℃/h and the condition that the part of the 17CrNiMo6 material is cracked due to too high temperature rise speed, which affects the whole production quality, and the condition that the heat treatment efficiency is too low due to too low temperature rise speed is avoided; the first preset temperature range is 930-960 ℃, the part is heated to the temperature range, and the whole austenitization in the part can be ensured to the maximum extent, so that the heat treatment quality of the 17CrNiMo6 material is improved; and after the temperature rise is finished, performing heat preservation for preset time, namely controlling the temperature in the trolley furnace to be stable and unchanged, and calculating the heat preservation time according to (0-10) min + (1.5-2) min and the thickness (mm) of the part.
Specifically, in step S3, the second preset temperature range is 550-.
Each temperature equalization is completed according to the same technical requirements, namely the process, time and temperature control of each temperature equalization are the same, and the parts are taken out of the trolley furnace after the temperature equalization is finished each time, placed in the air and naturally cooled to 550-650 ℃, after the temperature equalization for the last time is finished, the part is put into the trolley furnace again and cooled to the third preset temperature range along with the trolley furnace, namely 550 plus 600 ℃, after the temperature is cooled to 550-600 ℃, the heating source of the trolley furnace is opened again to heat the parts, the heating speed is less than or equal to 200 ℃/h, the hardness of the 17CrNiMo6 material can be reduced when the material is heated to a fourth preset temperature range, namely 600 plus 680 ℃, so that the heat treatment effect of the part meets the technical requirements, heat preservation is carried out after the heating is finished, and the holding time is calculated according to (20-60) min +2min parts thickness (mm).
Specifically, in step S4, after the requirement of the holding time is reached, the heating is stopped and the part is cooled to within 500 ℃ along with the trolley furnace, then the door of the trolley furnace is opened, the part is completely removed from the furnace along with the trolley, and the part is exposed in the air for natural cooling until the surface temperature of the part is consistent with the room temperature, and then the preliminary heat treatment process of the whole 17CrNiMo6 material is completed.
In this embodiment, the single treatment capacity of the 17CrNiMo6 material part, that is, the furnace loading weight is 10T, and the thickness of the part is 20mm, the heat preservation time in step S2 is 5min +2min 20-45 min, and the temperature equalization time is 0.5min 10-5 min; the heat preservation time in step S3 is 40min +2min 20-80 min, and the heating source of the car furnace is natural gas.
The specific implementation process of this embodiment is as follows:
in the first step, the parts made of 17CrNiMo6 material with the total amount of 10T are loaded on a trolley furnace, the distance between every two adjacent parts is set to be 40mm, and the charging temperature of the parts is 400 ℃.
And step two, opening a natural gas valve of the trolley furnace, raising the temperature in the trolley furnace to 950 ℃ at a speed of 180 ℃/h, and after the temperature in the trolley furnace reaches 950 ℃, carrying out heat preservation for 45min, namely controlling the temperature in the trolley furnace to be kept at 950 ℃ within 45min by controlling the natural gas valve.
And thirdly, after the heat preservation time reaches 45min, closing a natural gas valve to stop heating the trolley furnace, completely opening a furnace door of the trolley furnace, completely discharging the heated parts from the trolley furnace along with the trolley, exposing the parts in the air for natural cooling, and returning the parts into the trolley furnace for 3 times of cooling and temperature equalization when the surfaces of the parts are cooled to dark red, namely, cooled to 600 ℃.
Fourthly, for the first time, the temperature is equalized, the part is returned to the furnace, the surface temperature of the part can be gradually increased because the core temperature of the part is higher than the surface because the part is in the closed space in the furnace, the temperature difference between the core and the surface of the part can be reduced, the trolley furnace is not heated any more in the temperature equalizing process, and the temperature equalizing time is 5 min; after the first temperature equalization is finished, completely opening the part out of the trolley furnace along with the trolley again, exposing the part in the air for natural cooling, and returning the part into the trolley furnace for the second time temperature equalization with the duration of 5min when the surface of the part is cooled to dark red, namely, cooled to 600 ℃; the parts were homogenized in this way 3 times.
And fifthly, after the third temperature equalization is finished, completely taking out the part from the trolley furnace along with the trolley, exposing the part in the air for natural cooling, returning the part into the trolley furnace again when the surface of the part is cooled to dark red, namely cooled to 600 ℃, and closing a furnace door of the trolley furnace to cool the part to 600 ℃ along with the trolley furnace.
Sixthly, after the part is cooled to 600 ℃, opening a natural gas valve of the trolley furnace, raising the temperature in the trolley furnace to 680 ℃ at a speed of 200 ℃/h, and then carrying out heat preservation for 80min, namely controlling the temperature in the trolley furnace to be kept at 680 ℃ within 80min through the natural gas valve; and after the heat preservation time reaches 80min, stopping heating the trolley furnace, closing a natural gas valve of the trolley furnace, cooling the part to 500 ℃ along with the trolley furnace, opening a furnace door of the trolley furnace, completely opening the part along with the trolley from the trolley furnace, exposing the part in the air, and naturally cooling the part until the surface temperature of the part is consistent with the room temperature, thus finishing the whole preliminary heat treatment process of the 17CrNiMo6 material.
As shown in fig. 2, the temperature of the 17CrNiMo6 material is precisely controlled and changed with time during the whole pre-heat treatment process, and the 17CrNiMo6 material is cooled and equalized for many times, so that the 17CrNiMo6 material after heat treatment meets the grain size and hardness specifications required by the production process.
17CrNiMo6 belongs to low carbon alloy carburizing steel, is generally applied to key parts of high-power fans and internal combustion engines such as gears, input/output shafts and the like at present, and along with the updating and requirements of a production process, as the finished 17CrNiMo6 material can also relate to cutting processing subsequently, the control of the quality of heat treatment after forging the 17CrNiMo6 material is particularly important, generally speaking, the structure of the 17CrNiMo6 material after normalizing is required to be massive ferrite and pearlite, the hardness value is 160-200 HBW, the grain size is more than or equal to 5 grade, the hardenability of 17CrNiMo6 steel is better, and after carrying out preliminary heat treatment by adopting a common normalizing and tempering mode, bainite exists in the structure, the hardness value is more than 220HBW, and the requirements of cutting processing can not be met. Therefore, the preheating treatment is carried out by adopting an isothermal normalizing process in the production process, but the isothermal normalizing production line has high manufacturing cost, large floor area and difficult control of process setting parameters, and the production line is not arranged in a common factory, so that great difficulty is brought to the preheating treatment of the 17CrNiMo6 material.
In the scheme, the heat treatment mode of conventional normalizing and tempering and the isothermal normalizing heat treatment process are differentially researched, the change rule of the internal structure of the 17CrNiMo6 material in the two modes is deeply discussed, the whole heat treatment process can be completed by utilizing the conventional equipment such as a trolley furnace, wherein the largest difference point is the cooling operation after the 17CrNiMo6 material is heated, so that the complicated cooling operation in isothermal normalizing, such as accurate control of cold air quantity, cold air direction and the like, is avoided, in the scheme, the part is taken out after being heated and is naturally cooled, when the part is cooled to a preset temperature range, the part is cooled and equalized for multiple times, so that the temperature of each part and different parts of the same part in the cooling process is ensured to be the same, the cooling rate is also the same, and the structure in the 17CrNiMo6 material is controlled to be uniformly transformed to ferrite with pearlite, and meanwhile, bainite cannot be generated, and the hardness and the grain size of the 17CrNiMo6 material both meet the technical specification of the production process. On the whole, the heat treatment of the 17CrNiMo6 material can be rapidly completed by utilizing a conventional production line and combining multiple cooling and temperature equalization in the cooling process of the 17CrNiMo6 material and accurate control of the temperature of each link in the heat treatment process, the 17CrNiMo6 material is ensured to meet the technical requirements, the technical difficulty of the heat treatment of the 17CrNiMo6 material is effectively reduced, the heat treatment efficiency and quality of the 17CrNiMo6 material are greatly improved, no extra heat is provided in the temperature equalization process, the heat is completed only by using the residual heat in the trolley furnace, the residual heat in the trolley furnace is recycled, the energy waste is avoided, and the production cost of the 17CrNiMo6 material is effectively reduced.
The second embodiment:
this embodiment is basically the same as the first embodiment except that: and a circulating fan, particularly a blower, is fixedly arranged in the trolley furnace, and is used for stirring heat in the trolley furnace during part heating and part heat preservation.
The specific implementation process of this embodiment is basically the same as that of the first embodiment, except that:
and step two, opening a natural gas valve of the trolley furnace, raising the temperature in the trolley furnace to 950 ℃ at a speed of 180 ℃/h, carrying out heat preservation for 45min after the temperature in the trolley furnace reaches 950 ℃, namely controlling the temperature in the trolley furnace to be kept at 950 ℃ within 45min through controlling the natural gas valve, and synchronously opening a power supply of the air blower during heating and heat preservation so that the air blower stirs the heat in the trolley furnace.
And thirdly, after the heat preservation time reaches 45min, closing a natural gas valve to stop heating the trolley furnace, closing a power supply of an air blower, completely opening a furnace door of the trolley furnace, completely opening the heated part out of the trolley furnace along with the trolley, exposing the part in the air for natural cooling, and returning the part into the trolley furnace for 3 times of cooling and temperature equalization when the surface of the part is cooled to dark red, namely, to 600 ℃.
Through at the installation air-blower in the platform truck stove, during the platform truck stove heats spare part and part keeps warm in the platform truck stove, the air-blower drops into and begins work, provide wind-force and blow the stirring to the heat in the platform truck stove, thereby make the heat in the platform truck stove flow, and then make the distribution of heat in the stove more even, provide stable even heat and carry out stable heating and heat preservation to 17CrNiMo6 material, finally can effectively improve the preliminary heat treatment quality of 17CrNiMo6 material.
The foregoing is merely an example of the present invention, and common general knowledge in the field of known specific structures and characteristics is not described herein in any greater extent than that known in the art at the filing date or prior to the priority date of the application, so that those skilled in the art can now appreciate that all of the above-described techniques in this field and have the ability to apply routine experimentation before this date can be combined with one or more of the present teachings to complete and implement the present invention, and that certain typical known structures or known methods do not pose any impediments to the implementation of the present invention by those skilled in the art. It should be noted that, for those skilled in the art, without departing from the structure of the present invention, several variations and modifications can be made, which should also be considered as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the utility of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.
Claims (10)
1. A17 CrNiMo6 material preliminary heat treatment method is characterized in that: the method comprises the following steps:
s1, preparing a 17CrNiMo6 material to be subjected to heat treatment and heat treatment equipment, debugging parameters of the heat treatment equipment, mounting a part to be processed on the heat treatment equipment, and controlling the single treatment capacity of the part not to be larger than the maximum loading capacity of the heat treatment equipment;
step S2, heating the temperature in the heat treatment equipment to a first preset temperature range at a first preset heating speed, carrying out heat preservation for a preset time after the temperature is heated, stopping heating the equipment after the heat preservation time reaches the process heat preservation time, closing a heating source of the heat treatment equipment, completely opening a switch door of the heat treatment equipment, taking out the heated parts from the heat treatment equipment, and exposing the parts in the air for cooling;
step S3, when the part is cooled to a second preset temperature range, returning the part to the heat treatment equipment for cooling and temperature equalization for multiple times, after the temperature equalization is finished, cooling the part to the second preset temperature range again, returning the part to the heat treatment equipment, closing a switch door to cool the part to a third preset temperature range along with the heat treatment equipment, then heating the temperature in the heat treatment equipment to a fourth preset temperature range at a second preset speed, and carrying out heat preservation for a fixed time;
and step S4, stopping heating the heat treatment equipment after the process heat preservation time is reached, closing a heating source of the heat treatment equipment, cooling the part along with the heat treatment equipment to a fifth preset temperature range, taking the part out of the heat treatment equipment, and exposing the part in air for cooling until the surface temperature of the part is consistent with the room temperature.
2. The method for the preliminary heat treatment of the 17CrNiMo6 material, according to claim 1, wherein the method comprises the following steps: the heat treatment equipment is a trolley furnace.
3. The method for the preliminary heat treatment of the 17CrNiMo6 material, according to claim 1, wherein the method comprises the following steps: the debugging equipment parameters are that the trolley surface is adjusted to use a sizing block with the height of more than or equal to 100mm to isolate parts from the furnace bottom plate, the distance between adjacent parts is not less than 30mm, and the charging temperature of the parts is not more than 500 ℃.
4. The method for the preliminary heat treatment of the 17CrNiMo6 material as claimed in claim 1, wherein: and a circulating fan is also arranged in the heat treatment equipment and used for stirring heat in the equipment during heating and heat preservation of parts of the heat treatment equipment.
5. The method for the preliminary heat treatment of the 17CrNiMo6 material as claimed in claim 1, wherein: the uniform temperature is that the part is placed in the heat treatment equipment to exchange heat with the heat inside the heat treatment equipment.
6. The method for the preliminary heat treatment of the 17CrNiMo6 material as claimed in claim 5, wherein: and in the temperature equalizing process, stopping heating the heat treatment equipment and closing a switch door of the heat treatment equipment.
7. The method for the preliminary heat treatment of the 17CrNiMo6 material as claimed in claim 6, wherein: the number of times of temperature equalization is not more than 5, and each temperature equalization is completed according to the same technical requirements.
8. The method for the preliminary heat treatment of the 17CrNiMo6 material, according to claim 6, wherein the method comprises the following steps: and the temperature equalizing time is dynamically adjusted according to the single treatment capacity of the part.
9. The method for the preliminary heat treatment of the 17CrNiMo6 material, according to claim 1, wherein the method comprises the following steps: the exposure to air for cooling is that the parts are placed in air for natural cooling, and other auxiliary cooling equipment is not adopted in the process.
10. The method for the preliminary heat treatment of the 17CrNiMo6 material, according to claim 1, wherein the method comprises the following steps: and when the part is cooled to the second preset temperature range, measuring the temperature of the surface of the part by using an infrared thermometer.
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