CN112251712A - Carburizing treatment method for medium-carbon low-alloy steel - Google Patents
Carburizing treatment method for medium-carbon low-alloy steel Download PDFInfo
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- CN112251712A CN112251712A CN202011142853.0A CN202011142853A CN112251712A CN 112251712 A CN112251712 A CN 112251712A CN 202011142853 A CN202011142853 A CN 202011142853A CN 112251712 A CN112251712 A CN 112251712A
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- 238000005255 carburizing Methods 0.000 title claims abstract description 98
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 80
- 238000000034 method Methods 0.000 title claims abstract description 37
- 229910000851 Alloy steel Inorganic materials 0.000 title claims abstract description 25
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 62
- 238000009792 diffusion process Methods 0.000 claims abstract description 46
- 238000005496 tempering Methods 0.000 claims abstract description 35
- 238000004140 cleaning Methods 0.000 claims abstract description 30
- 238000010438 heat treatment Methods 0.000 claims abstract description 20
- 230000008595 infiltration Effects 0.000 claims abstract description 11
- 238000001764 infiltration Methods 0.000 claims abstract description 11
- 238000001035 drying Methods 0.000 claims abstract description 8
- 238000001816 cooling Methods 0.000 claims description 35
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 18
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 14
- 238000010583 slow cooling Methods 0.000 claims description 14
- 238000007599 discharging Methods 0.000 claims description 13
- 229910000831 Steel Inorganic materials 0.000 claims description 12
- 239000010959 steel Substances 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 11
- 239000001294 propane Substances 0.000 claims description 7
- 239000000428 dust Substances 0.000 claims description 6
- 239000012530 fluid Substances 0.000 claims description 6
- 239000003795 chemical substances by application Substances 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 3
- 239000003085 diluting agent Substances 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 239000001301 oxygen Substances 0.000 claims description 3
- 239000000523 sample Substances 0.000 claims description 3
- 238000009826 distribution Methods 0.000 abstract description 10
- 125000004432 carbon atom Chemical group C* 0.000 abstract description 4
- 230000002035 prolonged effect Effects 0.000 abstract description 4
- 238000004904 shortening Methods 0.000 abstract description 4
- 239000010410 layer Substances 0.000 description 12
- 238000010791 quenching Methods 0.000 description 5
- 230000000171 quenching effect Effects 0.000 description 5
- 229910001566 austenite Inorganic materials 0.000 description 4
- 238000005219 brazing Methods 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 239000002344 surface layer Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 229910001567 cementite Inorganic materials 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/20—Carburising
- C23C8/22—Carburising of ferrous surfaces
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Abstract
A carburizing treatment method for medium-carbon low-alloy steel comprises the following steps: 1) workpiece pretreatment: cleaning, drying and preheating the workpiece for later use; 2) strong infiltration treatment: transferring the workpiece pretreated in the step 1) into a carburizing furnace, heating to 900-930 ℃, and carrying out strong permeation treatment for 4.5-5.5 h; 3) and (3) diffusion treatment: after the strong cementation treatment is finished, keeping the temperature of the carburizing furnace unchanged, reducing the carbon potential of the workpiece to a preset diffusion carbon potential, and starting diffusion treatment for 5.5-7 hours; 4) carrying out temperature equalization treatment; 5) and (4) high-temperature tempering. The carburizing treatment method of the medium-carbon low-alloy steel reduces the number of active carbon atoms by shortening the strong carburizing treatment time, thereby properly reducing the carbon concentration of a carburized layer; and the diffusion treatment time is prolonged, so that the high carbon concentration on the surface of the workpiece is fully diffused inwards to obtain a carbon concentration gradient with slower distribution, the phenomenon of peeling of a carburized layer is avoided, and the quality of the workpiece is greatly improved.
Description
Technical Field
The invention relates to the technical field of heat treatment processes of steel, in particular to a carburizing treatment method for medium-carbon low-alloy steel such as steel for a drill bit.
Background
The heat treatment refers to a metal hot working process for obtaining expected structure and performance of a material in a solid state by means of heating, heat preservation and cooling, and at present, a carburization process is generally adopted for improving the surface wear resistance and strength of steel. Carburizing, which is a process of putting a part in a carburizing agent (carburizing medium), heating to a middle-phase austenite temperature, and preserving heat to enable carbon atoms to permeate into a surface layer of the part; the aim is to increase the carbon content in the surface layer of the part, the surface layer of the workpiece has high strength and wear resistance, and the central part of the workpiece still maintains the toughness and the shaping of low-carbon steel.
The carburizing process comprises a strong carburizing stage and a diffusion stage, and at present, the strong carburizing treatment time of the existing carburizing treatment process is longer than the diffusion treatment time, such as:
CN109457213A discloses a multistage carburizing heat treatment process, wherein the strong carburizing treatment time is 420min, the first diffusion carbon potential is 1.0, the second diffusion carbon potential is 0.65, and the first diffusion time and the second diffusion time are both 1 h.
CN107805776A discloses a carburizing carbon potential distribution control process of a material for a 23CrNi3MoA drill tool, which comprises the following steps: A. carburizing: the brazing tool adopts hot-rolled 23CrNi3MoA hollow steel, propane is used as a carburizing agent, methanol is used as a diluting agent, a workpiece is placed into a pit-type carburizing furnace for carburizing at 850 ℃, methanol is introduced when the temperature in the furnace reaches 780 ℃, propane is introduced when the temperature in the furnace reaches 860 ℃, the carbon potential is controlled by an infrared ray or an oxygen probe, the temperature is controlled by a thermocouple, the carburizing comprises two stages of forced carburizing and diffusion, and when the temperature in the furnace rises to 920 ℃, the carbon potential is controlled to be 1.1 percent of forced carburizing for 8 hours; then reducing the dropping amount of propane, controlling the carbon potential to be 0.6%, entering a diffusion stage, preserving heat for 2 hours, reducing the temperature in the furnace to 860 ℃ after carburization is finished, preserving heat for 1 hour, and discharging the workpiece from the furnace for air cooling quenching; B. quenching treatment: carrying out air cooling quenching on the brazing tool after carburization in the steps at 855-865 ℃, cooling to 300 ℃ at a cooling rate of more than or equal to 3 ℃/s, and cooling to room temperature at a cooling rate of more than or equal to 1 ℃/s; C. low-temperature tempering treatment: and (3) carrying out low-temperature tempering treatment on the brazing tool subjected to quenching treatment in the steps, wherein the tempering temperature is 210 ℃, and the tempering and heat preservation time is 100 minutes.
The existing carburizing process has long treatment period and is not beneficial to the gradient distribution of the carbon concentration in steel parts, and the distribution of the carbon concentration in the workpieces has great influence on the hardness and the strength of the workpieces in the carburizing process. The steel for the drill bit is a common steel part, and the requirement of the steel for the drill bit is high in hardness and strength, and simultaneously the hardness cannot be emphasized too much, because the excessive hardness can cause the material to become brittle and the toughness to be low, so that the existing carburizing process of medium-carbon low-alloy steel needs to be improved, the quality of workpieces is improved, and the processing period is shortened.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: overcomes the defects of the prior art, and provides the carburizing treatment method of the medium-carbon low-alloy steel, which has simple operation, obtains the workpiece with slower gradient distribution of the carbon concentration from the surface to the inside, reduces the cracking risk of the workpiece in use and prolongs the service life of the workpiece.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a carburizing treatment method for medium-carbon low-alloy steel comprises a strong carburizing treatment and a diffusion treatment, wherein the ratio of the time of the strong carburizing treatment to the time of the diffusion treatment is 1: 1.08-1.6, and the total time of the carburizing treatment is more than 10 hours.
The invention shortens the strong infiltration treatment time, prolongs the diffusion treatment time, reduces the number of active carbon atoms and further properly reduces the carbon concentration of the carburized layer on the premise of basically not adjusting the original carburization treatment process period; the high carbon concentration on the surface of the workpiece is fully diffused inwards to obtain a carbon concentration gradient with slower distribution, the phenomenon of peeling of a carburized layer is avoided, the quality of the workpiece is greatly improved, the prejudice of technicians in the industry on carburization in the prior art is broken, the quality of the workpiece such as steel for a drill bit is improved, and the subsequent machining treatment of the workpiece is facilitated.
The applicant finds that under the condition of maintaining the carburization time of the existing workpiece unchanged, when the diffusion time is less than 1.6 times of the strong cementation treatment time, the diffusion time is continuously prolonged, the gradient change of the carbon concentration along with the change of the depth of the surface of the workpiece is extremely small and tends to be smooth, and the concentration of the carburized layer of the surface of the workpiece is greatly reduced due to the shortening of the strong cementation time; when the diffusion time is less than 1.08 times of the strong infiltration treatment time, the diffusion time is continuously shortened, the influence of the diffusion stage on the carbon concentration distribution gradient is extremely obvious, a slower carbon concentration distribution gradient is difficult to obtain, and the phenomenon that a carburized layer is peeled off still easily occurs, so the ratio of the strong infiltration treatment time to the diffusion treatment time is set to be 1: 1.08-1.6, the surface of a workpiece is ensured to reach the carbon concentration meeting the requirement, the carbon concentration distribution gradient is slower, and the phenomenon that the carburized layer is peeled off is effectively avoided.
A carburizing treatment method for medium-carbon low-alloy steel comprises the following steps:
1) workpiece pretreatment: putting the workpiece on a special material rack, putting the workpiece in a cleaning furnace, cleaning the workpiece for 5-6 minutes by using cleaning fluid at 85-90 ℃, and cleaning oil stains and dust on the surface of the workpiece; transferring the cleaned workpiece into a tempering furnace, and drying and preheating at the temperature of 410 +/-10 ℃ for 30-45 minutes;
2) strong infiltration treatment: transferring the workpiece pretreated in the step 1) into a carburizing furnace, heating to 900-930 ℃, and carrying out strong permeation treatment for 4.5-5.5 h;
3) and (3) diffusion treatment: after the strong cementation treatment is finished, keeping the temperature of the carburizing furnace unchanged, reducing the carbon potential of the workpiece to a preset diffusion carbon potential, and starting diffusion treatment for 5.5-7 hours;
4) temperature equalization treatment: cooling a heating chamber of the carburizing furnace to 850 +/-10 ℃, preserving heat for 50-75 min, transferring the workpiece to a front chamber of the carburizing furnace, slowly cooling for 2-2.5 h, and then discharging the workpiece out of the furnace for air cooling;
5) high-temperature tempering: and (3) sending the workpiece which is air-cooled to 50-70 ℃ into a tempering furnace, tempering at the high temperature of 680 +/-10 ℃ for 5-6 h, then cooling to 580 ℃ along with the furnace, taking out the workpiece from the furnace, and placing the workpiece into a slow cooling tank for slow cooling.
In the step 2), the strong carburizing potential is 0.98-1.03.
In an exemplary embodiment, in the step 3), the predetermined diffused carbon potential is 0.63-0.68.
The carburizing agent adopted in the steps 2) and 3) is propane, the methanol is adopted as a diluent, and the carbon potential level is controlled by adjusting the flow rate of the propane and the methanol introduced into the carburizing furnace.
And in the steps 2) and 3), the carbon potential is detected by using an infrared ray or an oxygen probe, and the temperature is controlled by using a thermocouple.
The workpiece is steel for a drill bit, and the material of the workpiece is 23CrNi3 MoA.
The carburizing treatment method for the medium-carbon low-alloy steel has the beneficial effects that:
the applicant reduces the number of active carbon atoms by shortening the strong cementation treatment time, thereby properly reducing the carbon concentration of a carburized layer; the diffusion treatment time is prolonged, so that the high carbon concentration on the surface of the workpiece is fully diffused inwards to obtain a carbon concentration gradient with slower distribution, the phenomenon of peeling of a carburized layer is avoided, and the quality of the workpiece is greatly improved; and then high-temperature tempering treatment at 680 +/-10 ℃ is carried out, so that cementite on the metal surface of the carburized part is spheroidized, the carbon content in austenite is reduced after quenching, the austenite is easily converted into quenched martensite, the content of the retained austenite of the structure is reduced, the cracking risk of the workpiece in the use process is reduced, and the service life of the workpiece is prolonged. The high-temperature tempering is favorable for the unmelted cementite to exist in the form of dispersed granular carbide, so that the metallographic structure is improved, and the surface hardness of a carburized part is effectively improved.
Detailed Description
The present invention is further illustrated by the following examples.
Comparative example
A carburizing treatment method for medium-carbon low-alloy steel comprises the following steps:
1) workpiece pretreatment: putting the workpiece on a special material rack, putting the workpiece in a cleaning furnace, cleaning the workpiece for 5-6 minutes by using cleaning fluid at 85-90 ℃, and cleaning oil stains and dust on the surface of the workpiece; transferring the cleaned workpiece into a tempering furnace, and drying and preheating at the temperature of 410 +/-10 ℃ for 30-45 minutes;
2) strong infiltration treatment: transferring the workpiece pretreated in the step 1) into a carburizing furnace, heating to 920 +/-10 ℃, carrying out strong carburizing treatment for 6 hours, wherein the strong carburizing potential is 1.03;
3) and (3) diffusion treatment: after the strong cementation treatment is finished, keeping the temperature of the carburizing furnace unchanged, reducing the carbon potential of the workpiece to 0.68 of the preset diffusion carbon potential, and starting diffusion treatment for 5 hours;
4) temperature equalization treatment: cooling a heating chamber of the carburizing furnace to 850 +/-10 ℃, preserving heat for 60min, transferring the workpiece to a front chamber of the carburizing furnace, slowly cooling for 2h, discharging and air cooling;
5) high-temperature tempering: and (3) sending the workpiece which is air-cooled to 50-70 ℃ into a tempering furnace, tempering at the high temperature of 680 +/-10 ℃ for 6 hours, then cooling to 580 ℃ along with the furnace, discharging and placing into a slow cooling tank for slow cooling.
Example 1
The carburizing treatment method for the medium-carbon low-alloy steel of the embodiment comprises the following steps:
1) workpiece pretreatment: putting the workpiece on a special material rack, putting the workpiece in a cleaning furnace, cleaning the workpiece for 6 minutes by using cleaning fluid at 90 +/-5 ℃, and cleaning oil stains and dust on the surface of the workpiece; transferring the cleaned workpiece into a tempering furnace, and drying and preheating at the temperature of 410 +/-10 ℃ for 40 minutes;
2) strong infiltration treatment: transferring the workpiece pretreated in the step 1) into a carburizing furnace, heating to 920 +/-5 ℃, controlling the strong carburizing potential to be 1.03, and carrying out strong carburizing treatment for 5 hours;
3) and (3) diffusion treatment: after the strong cementation treatment is finished, keeping the temperature of the carburizing furnace unchanged, reducing the carbon potential of the workpiece to 0.66 of the preset diffusion carbon potential, and starting diffusion treatment for 6 hours;
4) temperature equalization treatment: cooling a heating chamber of the carburizing furnace to 850 +/-10 ℃, preserving heat for 60min, transferring the workpiece to a front chamber of the carburizing furnace, slowly cooling for 2h, discharging and air cooling;
5) high-temperature tempering: and (3) sending the workpiece which is air-cooled to 50-70 ℃ into a tempering furnace, tempering at the high temperature of 680 +/-10 ℃ for 6 hours, then cooling to 580 ℃ along with the furnace, discharging and placing into a slow cooling tank for slow cooling.
Example 2
The carburizing treatment method for the medium-carbon low-alloy steel of the embodiment comprises the following steps:
1) workpiece pretreatment: putting the workpiece on a special material rack, putting the workpiece in a cleaning furnace, cleaning the workpiece for 6 minutes by using cleaning fluid at 90 +/-5 ℃, and cleaning oil stains and dust on the surface of the workpiece; transferring the cleaned workpiece into a tempering furnace, and carrying out drying and preheating at the temperature of 410 +/-10 ℃ for 30 minutes;
2) strong infiltration treatment: transferring the workpiece pretreated in the step 1) into a carburizing furnace, heating to 920 +/-5 ℃, controlling the strong carburizing carbon potential at 1.0, and carrying out strong carburizing treatment for 4.8 h;
3) and (3) diffusion treatment: after the strong cementation treatment is finished, keeping the temperature of the carburizing furnace unchanged, reducing the carbon potential of the workpiece to 0.65 of the preset diffusion carbon potential, and starting diffusion treatment for 6.5 hours;
4) temperature equalization treatment: cooling a heating chamber of the carburizing furnace to 850 +/-10 ℃, preserving heat for 75min, transferring the workpiece to a front chamber of the carburizing furnace, slowly cooling for 2.2h, discharging and air cooling;
5) high-temperature tempering: and (3) sending the workpiece which is air-cooled to 50-70 ℃ into a tempering furnace, tempering at the high temperature of 680 +/-10 ℃ for 5 hours, then cooling to 580 ℃ along with the furnace, discharging and placing into a slow cooling tank for slow cooling.
Example 3
The carburizing treatment method for the medium-carbon low-alloy steel of the embodiment comprises the following steps:
1) workpiece pretreatment: putting the workpiece on a special material rack, putting the workpiece in a cleaning furnace, cleaning the workpiece for 6 minutes by using cleaning fluid at 90 +/-5 ℃, and cleaning oil stains and dust on the surface of the workpiece; transferring the cleaned workpiece into a tempering furnace, and drying and preheating at the temperature of 410 +/-10 ℃ for 40 minutes;
2) strong infiltration treatment: transferring the workpiece pretreated in the step 1) into a carburizing furnace, heating to 920 +/-5 ℃, controlling the strong carburizing carbon potential to be 1.03, and carrying out strong carburizing treatment for 4.5 h;
3) and (3) diffusion treatment: after the strong cementation treatment is finished, keeping the temperature of the carburizing furnace unchanged, reducing the carbon potential of the workpiece to 0.63 of the preset diffusion carbon potential, and starting diffusion treatment for 7 hours;
4) temperature equalization treatment: cooling a heating chamber of the carburizing furnace to 850 +/-10 ℃, preserving heat for 50min, transferring the workpiece to a front chamber of the carburizing furnace, slowly cooling for 2.5h, discharging and air cooling;
5) high-temperature tempering: and (3) sending the workpiece which is air-cooled to 50-70 ℃ into a tempering furnace, tempering at the high temperature of 680 +/-10 ℃ for 5.5h, then cooling to 580 ℃ along with the furnace, discharging and putting into a slow cooling tank for slow cooling.
Example 4
In the method for carburizing a medium carbon low alloy steel according to the present example, the following differences are present as compared with example 1:
2) strong infiltration treatment: transferring the workpiece pretreated in the step 1) into a carburizing furnace, heating to 920 +/-10 ℃, controlling the strong carburizing potential at 0.98, and carrying out strong carburizing treatment for 5.5 h;
3) and (3) diffusion treatment: after the strong cementation treatment is finished, the temperature of the carburizing furnace is kept unchanged, and after the carbon potential of the workpiece is reduced to 0.68 of the preset diffusion carbon potential, the diffusion treatment is started for 6 hours.
The applicant examined the surface carbon content and the depth of the carbon layer of the workpieces treated in the comparative examples and examples 1 to 4, and the results are shown in table 1.
TABLE 1 correlation of surface carbon content to carbon layer depth profile for work pieces treated in comparative examples and examples 1-4
As can be seen from Table 1, the carburizing treatment method for the medium-carbon low-alloy steel remarkably slows down the gradient of the carbon concentration of the carburized layer on the surface of the steel workpiece along with the change of the depth of the carbon layer by shortening the strong carburizing treatment time and prolonging the diffusion treatment time, avoids the peeling phenomenon of the carburized layer, and greatly improves the workpiece quality.
The invention relates to a carburizing treatment method of medium-carbon low-alloy steel, wherein the temperature and the cleaning time of a cleaning solution for pretreatment can be properly adjusted according to the size of a workpiece, such as the following steps: cleaning with a cleaning solution at 85 ℃ for 5 minutes; the time of the temperature equalization treatment and the high temperature tempering can be adjusted within a range, for example, the temperature equalization treatment: cooling a heating chamber of the carburizing furnace to 850 +/-10 ℃, preserving heat for 55min, transferring the workpiece to a front chamber of the carburizing furnace, slowly cooling for 2.5h, discharging and air cooling; 5) high-temperature tempering: sending the workpiece which is air-cooled to 50-70 ℃ into a tempering furnace, tempering at the high temperature of 680 +/-10 ℃ for 5 hours, then cooling to 580 ℃ along with the furnace, discharging and putting into a slow cooling tank for slow cooling; the above technical features can be understood and implemented by those skilled in the art through the text description, and therefore, the accompanying drawings are not needed to be described.
Claims (8)
1. The carburizing treatment method of the medium-carbon low-alloy steel is characterized in that the carburizing treatment comprises strong carburizing treatment and diffusion treatment, the ratio of the time of the strong carburizing treatment to the time of the diffusion treatment is 1: 1.08-1.6, and the total time of the carburizing treatment is more than 10 hours.
2. A carburizing treatment method for medium-carbon low-alloy steel is characterized by comprising the following steps:
1) workpiece pretreatment: cleaning, drying and preheating the workpiece for later use;
2) strong infiltration treatment: transferring the workpiece pretreated in the step 1) into a carburizing furnace, heating to 900-930 ℃, and carrying out strong permeation treatment for 4.5-5.5 h;
3) and (3) diffusion treatment: after the strong cementation treatment is finished, keeping the temperature of the carburizing furnace unchanged, reducing the carbon potential of the workpiece to a preset diffusion carbon potential, and starting diffusion treatment for 5.5-7 hours;
4) temperature equalization treatment: cooling a heating chamber of the carburizing furnace to 850 +/-10 ℃, preserving heat for 50-75 min, transferring the workpiece to a front chamber of the carburizing furnace, slowly cooling for 2-2.5 h, and then discharging the workpiece out of the furnace for air cooling;
5) high-temperature tempering: and (3) sending the workpiece which is air-cooled to 50-70 ℃ into a tempering furnace, tempering at the high temperature of 680 +/-10 ℃ for 5-6 h, then cooling to 580 ℃ along with the furnace, taking out the workpiece from the furnace, and placing the workpiece into a slow cooling tank for slow cooling. .
3. A method for carburizing medium carbon low alloy steel according to claim 1, characterized in that the specific operation of the workpiece pretreatment is: putting the workpiece on a special material rack, putting the workpiece in a cleaning furnace, cleaning the workpiece for 5-6 minutes by using cleaning fluid at 85-90 ℃, and cleaning oil stains and dust on the surface of the workpiece; and transferring the cleaned workpiece into a tempering furnace, and drying and preheating at the temperature of 410 +/-10 ℃ for 30-45 minutes.
4. A carburizing treatment method for medium carbon low alloy steel according to claim 1, wherein in said step 2), said strong carburizing potential is 0.98 to 1.03.
5. A carburizing treatment method for medium carbon low alloy steel according to claim 1, wherein in said step 3), said predetermined diffused carbon potential is 0.63 to 0.68.
6. A process for carburizing a medium carbon low alloy steel according to claim 4 or 5, wherein the carburizing agent used in steps 2) and 3) is propane, methanol is used as a diluent, and the carbon potential level is controlled by adjusting the flow rates of propane and methanol to the carburizing furnace.
7. A carburizing treatment method for medium carbon low alloy steel according to claim 1, wherein in said steps 2) and 3), the carbon potential is detected by an infrared ray or an oxygen probe, and the temperature is controlled by a thermocouple.
8. A carburization treatment method of medium carbon low alloy steel according to claim 7, characterized in that said workpiece is a steel for drill bit, and its material is 23CrNi3 MoA.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112981309A (en) * | 2021-02-07 | 2021-06-18 | 南京宇能机械有限公司 | 18CrNiMo7-6 wind power gear carburizing process and equipment |
| CN113322428A (en) * | 2021-05-26 | 2021-08-31 | 盐城市金洲机械制造有限公司 | Heat treatment method for gear of speed reducer |
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| JP2002212642A (en) * | 2001-01-10 | 2002-07-31 | Ntn Corp | Gas carburized hardening method of rolling-formed parts and rolling-formed parts obtained with this method |
| CN106521402A (en) * | 2016-11-29 | 2017-03-22 | 金川集团股份有限公司 | Whole heat treatment method for 23CrNi3MoA hollow steel rock drill rod |
| CN106756753A (en) * | 2016-12-12 | 2017-05-31 | 中车戚墅堰机车车辆工艺研究所有限公司 | The carburization quenching method of low-speed heavy-loaded gear |
| CN107805776A (en) * | 2017-10-23 | 2018-03-16 | 金川集团股份有限公司 | A kind of carburizing carbon potential DISTRIBUTION CONTROL PROCESS of 23CrNi3MoA drilling tools material |
| CN110951962A (en) * | 2019-12-16 | 2020-04-03 | 武汉理工大学 | High-performance gear heat treatment method for realizing fine and homogenized structure |
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