CN114574683A - Heat treatment method of low-carbon low-alloy steel bit leg bearing casting and bit leg bearing - Google Patents
Heat treatment method of low-carbon low-alloy steel bit leg bearing casting and bit leg bearing Download PDFInfo
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- CN114574683A CN114574683A CN202210178176.0A CN202210178176A CN114574683A CN 114574683 A CN114574683 A CN 114574683A CN 202210178176 A CN202210178176 A CN 202210178176A CN 114574683 A CN114574683 A CN 114574683A
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- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 60
- 238000010438 heat treatment Methods 0.000 title claims abstract description 56
- 238000000034 method Methods 0.000 title claims abstract description 39
- 238000005266 casting Methods 0.000 title claims abstract description 33
- 229910000851 Alloy steel Inorganic materials 0.000 title claims abstract description 24
- 238000010791 quenching Methods 0.000 claims abstract description 76
- 230000000171 quenching effect Effects 0.000 claims abstract description 73
- 238000005496 tempering Methods 0.000 claims abstract description 57
- 230000006698 induction Effects 0.000 claims abstract description 49
- 238000005255 carburizing Methods 0.000 claims abstract description 47
- 239000000956 alloy Substances 0.000 claims abstract description 7
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 6
- 238000001816 cooling Methods 0.000 claims description 38
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 31
- 238000007599 discharging Methods 0.000 claims description 20
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 9
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 9
- 238000004140 cleaning Methods 0.000 claims description 8
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 6
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 6
- 230000001681 protective effect Effects 0.000 claims description 5
- 238000005507 spraying Methods 0.000 claims description 5
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 claims description 3
- 239000003795 chemical substances by application Substances 0.000 claims description 3
- 238000009792 diffusion process Methods 0.000 claims description 3
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims description 3
- 239000001294 propane Substances 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 230000008595 infiltration Effects 0.000 claims description 2
- 238000001764 infiltration Methods 0.000 claims description 2
- 239000011159 matrix material Substances 0.000 abstract description 11
- 239000010410 layer Substances 0.000 description 26
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 25
- 230000000052 comparative effect Effects 0.000 description 16
- 230000008569 process Effects 0.000 description 15
- 229910052757 nitrogen Inorganic materials 0.000 description 13
- 239000000463 material Substances 0.000 description 12
- 238000004321 preservation Methods 0.000 description 6
- 238000005096 rolling process Methods 0.000 description 6
- 238000004320 controlled atmosphere Methods 0.000 description 5
- 238000005242 forging Methods 0.000 description 5
- 238000005553 drilling Methods 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- 239000008399 tap water Substances 0.000 description 3
- 235000020679 tap water Nutrition 0.000 description 3
- FBPFZTCFMRRESA-JGWLITMVSA-N D-glucitol Chemical group OC[C@H](O)[C@@H](O)[C@H](O)[C@H](O)CO FBPFZTCFMRRESA-JGWLITMVSA-N 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- 229910001339 C alloy Inorganic materials 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 229910000859 α-Fe Chemical group 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/40—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rings; for bearing races
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/06—Surface hardening
- C21D1/09—Surface hardening by direct application of electrical or wave energy; by particle radiation
- C21D1/10—Surface hardening by direct application of electrical or wave energy; by particle radiation by electric induction
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- 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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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B10/00—Drill bits
- E21B10/08—Roller bits
- E21B10/22—Roller bits characterised by bearing, lubrication or sealing details
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Abstract
The invention discloses a heat treatment method of a low-carbon low-alloy steel bit leg bearing casting and a bit leg bearing, wherein the heat treatment method comprises the following steps: performing integral quenching after carburizing the cast-state palm bearing, performing high-temperature tempering at the temperature of 570 plus 590 ℃, then placing the palm bearing subjected to high-temperature tempering on high-frequency induction quenching equipment, and moving the palm bearing and an induction coil at a relative speed of 2-4mm/s under the power of 5-7KHz so as to ensure that the depth of an induction quenching hardened layer is higher than that of a carburized layer; and finally, low-temperature tempering is carried out at 180-plus-200 ℃, the method solves the problem that the low-carbon low-alloy bit leg bearing casting cannot give consideration to both the plastic toughness and the surface wear resistance of the matrix, ensures the plasticity and the toughness of the cast low-carbon low-alloy bit leg bearing matrix, ensures that the cast low-carbon low-alloy bit leg bearing matrix has better service performance when being subjected to complex impact load, obviously improves the hardness and the depth of a hardened layer on the surface of the bit leg bearing, and greatly improves the wear resistance of the bit leg bearing.
Description
Technical Field
The invention belongs to the field of petroleum drilling tools, and relates to a heat treatment method of a low-carbon low-alloy steel bit leg bearing casting and a bit leg bearing.
Background
The tricone bit is a drilling tool widely used in petroleum drilling, and a palm bearing of the tricone bit is manufactured by adopting a low-carbon alloy forging material and a carburizing and quenching low-temperature tempering heat treatment process, so that the high hardness, high wear resistance and matrix toughness of the surface of the palm bearing are ensured. Aiming at some special structure bit leg bearings, when the designed structure cannot be realized by forging or the cost is too high, a casting forming process can be adopted. But compared with the forging material, the casting material has no rolling and forging compression process, and the material is more brittle due to too coarse grains and structures.
At present, the material for the bearing of the palm of teeth is mainly low-carbon low-alloy steel, the representative mark is ZG20CrNiMo, and the main components are C: 0.17-0.21%; cr: 0.9 to 1.1 percent; ni: 0.6-0.9%; mo: 0.25-0.35%; mn: 0.60-0.90%; si: 0.17-0.37%. Less than or equal to 0.025 percent of S; p is less than or equal to 0.025 percent; cu less than or equal to 0.20 percent, and the balance of Fe. When the material is used for a bearing of a tooth leg, the plastic toughness of a base body of the bearing of the tooth leg is too low by adopting a conventional forging material and a carburizing and quenching low-temperature tempering heat treatment process, so that the performance requirement of SY/T5164 tricone bit on cast tooth leg cannot be met. In the prior art, the plasticity and toughness of a casting material matrix are generally improved by adopting a quenching and tempering heat treatment process, but the depth and hardness of a hardened layer on the surface of a bearing of a tooth leg cannot meet the performance requirements of products when the quenching and tempering process is adopted, namely the requirements of casting tooth leg products on the plasticity and toughness of the core part and the performance of the hardened layer of the bearing of the tooth leg cannot be met simultaneously according to the conventional heat treatment process.
Disclosure of Invention
In order to solve the problem that the surface performance and the core performance of the existing low-carbon low-alloy steel bit leg bearing casting cannot be considered at the same time, the invention provides a composite heat treatment process capable of effectively improving the hardness and the depth of a hardened layer on the surface of the low-carbon low-alloy steel bit leg bearing casting and the plasticity and the toughness of a matrix.
The technical scheme provided by the invention is as follows:
in a first aspect, the invention provides a heat treatment method for a low-carbon low-alloy steel bit leg bearing casting, which comprises the following steps:
integral quenching: putting the cast-state palm bearing into a quenching furnace after carburizing treatment, heating to 870-890 ℃ in a carburizing atmosphere with the carbon concentration of 0.4-0.6%, preserving heat, taking out of the furnace, and immersing into quenching oil for cooling for 20-30 minutes;
high-temperature tempering: placing the integrally quenched bearing in a tempering furnace, heating to 570-590 ℃ in a protective atmosphere, preserving heat, and cooling in air to room temperature after discharging;
surface induction quenching: placing the palm bearing subjected to high-temperature tempering on high-frequency induction quenching equipment, and moving the palm bearing and the induction coil at a relative speed of 2-4mm/s under the power of 5-7KHz so as to ensure that the depth of an induction quenching hardened layer is higher than that of a carburized layer;
low-temperature tempering: and (3) placing the bearing of the palm of teeth after finishing the surface induction quenching in a tempering furnace, heating to 180-200 ℃, preserving heat, and cooling to room temperature after discharging.
Preferably, the temperature of the entire quenching is 880 ℃.
Preferably, the temperature of the first tempering is 580 ℃.
Preferably, the low temperature tempering is performed at 190 ℃.
Preferably, the carburizing process includes:
a. carrying out strong infiltration treatment on the bearing of the bit leg under the conditions of carburizing atmosphere with the carbon concentration of 1.20-1.30% and the temperature of 920-;
b. c, performing diffusion treatment on the bearing of the bit leg treated in the step a under the carburizing atmosphere with the carbon concentration of 0.90-1.10% and at the temperature of 890-910 ℃;
c. and c, cooling the palm bearing treated in the step b to below 300 ℃ in a protective atmosphere, and air-cooling to room temperature after discharging.
In the above-described aspect, the carburizing agent used in the carburizing atmosphere is preferably any one or more of methanol, ethane, propane, ethanol, propanol, and ethyl acetate.
Preferably, a cleaning step is further arranged between the integral quenching step and the high-temperature tempering step, the cleaning solution adopted in the cleaning step is 100 +/-10 ℃, and the cleaning time is 0.5-1.5 hours.
Preferably, in the technical scheme, the low-carbon low-alloy steel bit leg bearing is made of ZG20CrNiMo alloy, and comprises the following components in percentage by weight: 0.17% -0.21% of C; 0.9 to 1.1 percent of Cr; 0.6% -0.9% of Ni; 0.25% -0.35% of Mo; 0.60-0.90% Mn; 0.17% -0.37% of Si; less than or equal to 0.025 percent of S; p is less than or equal to 0.025 percent; cu less than or equal to 0.20 percent, and the balance being Fe.
Preferably, the coil sprays water with the temperature of 20-50 ℃ at the rear side of the induction coil, and the heated part is continuously sprayed and quenched synchronously until the surface induction quenching is finished.
Preferably, the protective atmosphere is nitrogen.
In a second aspect, the invention provides a low-carbon low-alloy steel bit leg bearing prepared by the heat treatment method.
Compared with the prior art, the invention has the following advantages:
the invention solves the problem that the low-carbon low-alloy steel bit leg bearing casting cannot give consideration to both the plasticity and the surface wear resistance of the matrix, and ensures the plasticity and the toughness of the matrix of the low-carbon low-alloy bit leg bearing casting, so that the low-carbon low-alloy steel bit leg bearing casting has better service performance when being subjected to complex impact load. In addition, the invention obviously improves the hardness and the depth of the hardened layer on the surface of the bearing of the bit leg, and greatly improves the wear resistance of the bearing of the bit leg. In addition, the surface of the bearing of the tooth leg is subjected to high-frequency induction quenching, so that larger residual compressive stress is formed on the surface of the bearing of the tooth leg, and the fatigue resistance of the bearing of the tooth leg is improved. In one aspect, for rolling element bearings, the surface residual compressive stress may enhance the rolling element bearing surface contact fatigue strength. On the other hand, for a sliding leg bearing, the surface residual compressive stress can reduce the detrimental effects of the sliding adhesion gap on fatigue performance. The use performance of the palm bearing is greatly improved.
Drawings
FIG. 1 is a comparison of the hardness gradients of the hardened layers of the bearing of the present invention and the bearing of the palm ends prepared in comparative examples 1 to 3.
Fig. 2 is a schematic layout view of a bearing of a bit leg during surface induction hardening according to an embodiment of the present invention.
FIG. 3 is a metallographic image of a hard-surface layer of a bearing according to an embodiment of the present invention.
Fig. 4 is a core phase diagram of a palm bearing prepared according to an embodiment of the present invention.
Detailed Description
The following examples are provided to further illustrate the present invention for better understanding, but the present invention is not limited to the following examples.
Unless otherwise stated, the cast-state bit leg bearings carburized according to the examples and comparative examples of the present invention were cast and molded by a general casting process and machined, and the material brand was ZG20CrNiMo, and typical components included in weight percent: 0.17-0.21% of C; 0.9-1.1% of Cr; 0.6-0.9% Ni; 0.25-0.35% of Mo; 0.60-0.90% Mn; 0.17-0.37% Si; less than or equal to 0.025 percent of S; p is less than or equal to 0.025 percent; cu less than or equal to 0.20 percent, and the balance of Fe. However, the material of the bearing of the bit leg in the present invention is not limited to this, and other low-carbon and low-alloy materials may be used.
The method for carrying out heat treatment on the palm bearing casting with the material brand ZG20CrNiMo comprises the following steps:
carburizing: placing the cast-state bit leg bearing in a carburizing furnace, and performing carburizing treatment in a carburizing atmosphere with the carbon concentration of 0.90-1.30%;
integral quenching: placing the carburized bearing in a controlled atmosphere quenching furnace, heating to 870-890 ℃ in an atmosphere with the carbon concentration of 0.4-0.6%, preserving the temperature, immediately immersing in quenching oil after discharging, and cooling for 20-30 minutes;
high-temperature tempering: placing the integrally quenched bearing in a tempering furnace, heating to 570-590 ℃ under the protection of nitrogen, preserving heat, and cooling to room temperature after discharging;
surface induction quenching: and (3) placing the palm bearing subjected to high-temperature tempering on induction quenching equipment, moving the palm bearing and the induction coil at a relative speed of 2-4mm/s under the power of 5-7KHz, and synchronously spraying water for cooling the coil until the surface quenching is finished. The power and the moving speed can ensure that the depth of the induction hardening layer is higher than that of the carburized layer.
Tempering at low temperature; and (3) placing the palm bearings subjected to surface induction quenching in a tempering furnace, heating to 180-200 ℃, preserving heat, and cooling in air to room temperature after discharging.
According to the technical scheme in the embodiment of the invention, the procedure of carburizing the cast-state bit leg bearing with the material brand ZG20CrNiMo is as follows:
a. placing the cast-state bit leg bearing in a carburizing furnace, and carrying out strong carburizing treatment at 920-940 ℃ in a carburizing atmosphere with the carbon concentration of 1.20-1.30%;
b. c, performing diffusion treatment on the bearing of the bit leg treated in the step a under the carburizing atmosphere with the carbon concentration of 0.90-1.10% and at the temperature of 890-910 ℃;
c. c, cooling the bearing of the tooth leg treated in the step b to below 300 ℃ in a nitrogen protective atmosphere, discharging the bearing out of the furnace, and cooling the bearing to room temperature;
in the above carburizing treatment, the carbon concentration in step a is preferably 1.25%, and the carbon concentration in step b is preferably 1.0%. And c, filling nitrogen with the purity of 99.8% into a cooling device to cool the bearing of the bit leg in the step c. The carburizing agent adopted in the carburizing atmosphere is any one or more of methanol, ethane, propane, ethanol, propanol and ethyl acetate.
Step a is a strong cementation process, which can make carbon atoms fully diffuse to the surface of a bearing of a bit leg to form a carburized layer with a certain depth on the surface; step b, reducing the carbon concentration in the carburizing atmosphere, so that the carbon gradient of the carburized layer of the bearing of the bit leg can be smoother, the hardness gradient of the final carburized layer is improved, the residual austenite content of the carburized layer after quenching is reduced, and the risk of forming microcracks on the near surface of the bearing of the bit leg under high carbon and high hardness is reduced; and c, cooling under the protection of nitrogen, so that the surface decarburization of the carburized layer can be reduced.
According to the invention, after the carburization treatment, the bearing of the bit leg is subjected to integral quenching treatment: and (3) placing the carburized bearing of the palm of the teeth in a quenching furnace, heating to 870-890 ℃, keeping the carbon concentration in the furnace at 0.4-0.6%, taking out the bearing of the teeth from the furnace, immersing the bearing of the teeth in quenching oil, cooling for 20-30 minutes, and stirring the quenching oil at 800-900 revolutions per minute. The certain carbon concentration is maintained during the quenching and heat preservation, and the decarburization in the quenching and heat preservation process of the carburized surface can be reduced.
And after the integral quenching, carrying out high-temperature tempering treatment on the bearing of the tooth palm, putting the bearing into a box type tempering furnace, and carrying out high-temperature tempering under the protection of nitrogen. The high-temperature tempering heat preservation temperature is 570-. The whole quenching and high-temperature tempering treatment improves the plasticity and the toughness of the core part of the tooth palm. At the moment, the metallographic phase of the center part of the bearing of the bit leg is mainly based on a tempered sorbite and a ferrite structure, the metallographic phase of the carburized layer is mainly based on the tempered sorbite, and a certain amount of residual austenite exists.
After high-temperature tempering, the bearing of the bearing leg is subjected to high-frequency induction quenching of the surface layer of the carburized layer. The induction coil is 3-5mm away from the outer circle surface of the bearing of the bit leg, the heating frequency is 5-7KHz, and the coil and the bearing of the bit leg move relatively at the speed of 2-4 mm/s. Meanwhile, at the rear side of the induction coil, the coil sprays 20-50 ℃ tap water to synchronously and uninterruptedly spray and quench the heated part on the bearing of the bit leg until the surface induction quenching heating is finished. Through the control of power and moving speed, the depth of the surface induction quenching hardened layer is ensured to be higher than the depth of the carburized layer, so that the hardness of the hardened layer is changed in a gradient manner along with the gradient change of carbon.
And after the surface induction quenching is finished, carrying out low-temperature tempering on the bearing of the bit leg. The low-temperature tempering heat preservation temperature is 180-190 ℃, and the air cooling after the heat preservation is finished.
In the above carburizing treatment process, the carburizing and holding time and the carbon concentration may be adjusted as necessary. The overall quenching, high temperature tempering and low temperature tempering heat preservation time can be determined according to the size of the bearing of the bit leg and the charging amount, and belongs to the conventional technical means of technicians in the field.
The following specific examples are provided to illustrate the effects of the present invention, but the scope of the present invention is not limited by the following examples.
Example (b):
the embodiment provides a heat treatment method of a bearing casting of a cone leg of a tricone bit, which comprises the following steps:
(1) carburizing:
a. placing the cast-state bit leg bearing in a carburizing furnace, and carrying out forced carburizing for 14.5 hours at the temperature of 930 ℃ in the atmosphere with the carbon concentration of 1.25%;
b. b, diffusing the bearing of the palm after being treated in the step a for 3 hours at 900 ℃ in an atmosphere with the carbon concentration of 0.94%;
c. cooling the bearing of the bit leg processed in the step b to below 300 ℃ under the protection of nitrogen, discharging and air cooling;
(2) integral quenching treatment
Placing the carburized bearing of the bit leg in a controlled atmosphere quenching furnace, heating to 880 ℃ in an atmosphere with the carbon concentration of 0.5%, preserving the heat for 3 hours, taking out of the furnace, immersing in quenching oil, and cooling for 30 minutes;
(3) high temperature tempering
Placing the integrally quenched bearing of the tooth palm in a tempering furnace, heating to 580 ℃ under the protection of nitrogen, preserving heat for 4 hours, discharging and air cooling;
(4) surface induction hardening
As shown in fig. 2, the bit leg bearing after high temperature tempering is placed on the rotating shaft of the induction quenching equipment, and the induction coil is arranged along the outer surface of the bit leg bearing and is fixed. The heating frequency of the induction coil is set to be 6KHz, and the rotating speed of the rotating shaft is set, so that the bearing surface of the bit leg rotates relative to the induction coil at the speed of 3 mm/s. In the heating process, spraying tap water at 20-30 ℃ on the rear side of the induction coil to synchronously quench the part of the bearing surface of the bit leg, which is just heated;
(5) low temperature tempering
And (3) placing the bearing of the bit leg after the surface induction quenching in a tempering furnace, heating to 190 ℃, preserving the heat for 4 hours, discharging and air cooling.
Comparative example 1
Unlike the examples, this comparative example was subjected to only the bulk quenching treatment and the low-temperature tempering treatment after the carburizing treatment.
The heat treatment method for the palm bearing casting provided by the comparative example comprises the following steps:
(1) carburizing:
a. placing the cast-state bit leg bearing in a carburizing furnace, and carrying out forced carburizing for 14.5 hours at the temperature of 930 ℃ in the atmosphere with the carbon concentration of 1.25%;
b. b, diffusing the bearing of the palm after being treated in the step a for 3 hours at 900 ℃ in an atmosphere with the carbon concentration of 0.94%;
c. cooling the bearing of the bit leg processed in the step b to below 300 ℃ under the protection of nitrogen, discharging and air cooling;
(2) integral quenching treatment
Placing the carburized bearing of the bit leg in a controlled atmosphere quenching furnace, heating to 880 ℃ in an atmosphere with the carbon concentration of 0.5%, preserving the heat for 3 hours, taking out of the furnace, immersing in quenching oil, and cooling for 30 minutes;
(3) low temperature tempering
And (3) placing the palm bearings subjected to the integral quenching treatment in a tempering furnace, heating to 190 ℃, preserving the heat for 4 hours, discharging from the furnace and air cooling.
Comparative example 2
Unlike the examples, this comparative example was subjected to only the bulk quenching treatment and the high temperature tempering treatment after the carburizing treatment.
The heat treatment method for the palm bearing casting provided by the comparative example comprises the following steps:
(1) carburizing treatment:
a. placing the cast-state bit leg bearing in a carburizing furnace, and carrying out forced carburizing for 14.5 hours at the temperature of 930 ℃ in the atmosphere with the carbon concentration of 1.25%;
b. b, diffusing the bearing of the palm after being treated in the step a for 3 hours at 900 ℃ in an atmosphere with the carbon concentration of 0.94%;
c. cooling the bearing of the bit leg processed in the step b to below 300 ℃ under the protection of nitrogen, discharging and air cooling;
(2) integral quenching treatment
Placing the carburized bearing of the bit leg in a controlled atmosphere quenching furnace, heating to 880 ℃ in an atmosphere with the carbon concentration of 0.5%, preserving the heat for 3 hours, taking out of the furnace, immersing in quenching oil, and cooling for 30 minutes;
(3) high temperature tempering
And (3) placing the integrally quenched bearing of the tooth palm in a tempering furnace, heating to 580 ℃ under the protection of nitrogen, preserving the heat for 4 hours, discharging and air cooling.
Comparative example 3
Unlike the examples, the induction heating frequency of this comparative example was 15 KHz.
The heat treatment method for the palm bearing casting provided by the comparative example comprises the following steps:
(1) carburizing:
a. placing the cast-state bit leg bearing in a carburizing furnace, and carrying out forced carburizing for 14.5 hours at the temperature of 930 ℃ in the atmosphere with the carbon concentration of 1.25%;
b. b, diffusing the bearing of the palm after being treated in the step a for 3 hours at 900 ℃ in an atmosphere with the carbon concentration of 0.94%;
c. cooling the bearing of the bit leg processed in the step b to below 300 ℃ under the protection of nitrogen, discharging and air cooling;
(2) integral quenching treatment
Placing the carburized palm bearing in a controlled atmosphere quenching furnace, heating to 880 ℃ in an atmosphere with the carbon concentration of 0.5%, preserving the heat for 3 hours, taking out of the furnace, immersing in quenching oil, and cooling for 30 minutes;
(3) high temperature tempering
Placing the integrally quenched bearing of the tooth palm in a tempering furnace, heating to 580 ℃ under the protection of nitrogen, preserving heat for 4 hours, discharging and air cooling;
(4) surface induction hardening
As shown in fig. 2, the bit leg bearing after high temperature tempering is placed on the rotating shaft of the induction quenching equipment, and the induction coil is arranged along the outer surface of the bit leg bearing and is fixed. The heating frequency of the induction coil is set to be 15KHz, and the rotating speed of the rotating shaft is set, so that the bearing surface of the palm rotates relative to the induction coil at the speed of 3 mm/s. In the heating process, spraying tap water at 20-30 ℃ on the rear side of the induction coil to synchronously quench the part of the bearing surface of the bit leg, which is just heated;
(5) low temperature tempering
And (3) placing the bearing of the bit leg after the surface induction quenching in a tempering furnace, heating to 190 ℃, preserving the heat for 4 hours, discharging and air cooling.
Sampling tests were performed on the heat-treated leg bearings of examples and comparative examples 1 to 3, and the specific sampling results are shown in table 1.
TABLE 1 plasticity and toughness of heat-treated bearing matrix of bit leg in examples and comparative examples of the present invention
The results in fig. 1 show that, after the cast-state bit leg bearing is treated by the embodiment, the hardness and the depth of the hardened layer are higher than those of the bit leg bearing surface of the conventional bit leg bearing in the processes of carburizing, integral quenching and low-temperature tempering (comparative example 1). Referring to fig. 1 and table 1, in comparative example 2, after carburization, integral quenching and high-temperature tempering process heat treatment, the plasticity and toughness of the bearing matrix of the bit leg bearing are equivalent to those of the example, but the hardness of the hardened layer on the surface of the bit leg bearing is too low, so that the wear resistance of the bit leg bearing is greatly reduced. In addition, fig. 1 also shows that, when the carburized layer is not completely covered by the induction hardening layer during the surface induction hardening process after carburization, bulk quenching and high-temperature tempering (comparative example 3), a sharp drop in hardness occurs at the interface between the induction hardening layer and the non-induction hardening layer, and when the hardness is distributed on the bearing surface of the leg portion, early cracking and peeling of the bearing surface of the leg portion are likely to occur during use. Particularly, when the interface is applied to a rolling bearing, if the interface is present at the maximum dynamic shear stress in which the rolling bearing is used, the rolling fatigue failure of the bearing is likely to occur. That is to say, by adopting the heat treatment process, the problem of insufficient plastic toughness of the matrix of the bearing casting of the bit leg is solved, the depth and hardness of a hardened layer on the surface of the bearing casting of the bit leg can be obviously improved, and the wear resistance and the fatigue resistance of the bearing of the bit leg are further improved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A heat treatment method for a low-carbon low-alloy steel bit leg bearing casting is characterized by comprising the following steps:
integral quenching: putting the cast-state palm bearing into a quenching furnace after carburizing treatment, heating to 870-890 ℃ in a carburizing atmosphere with the carbon concentration of 0.4-0.6%, preserving heat, taking out of the furnace, and immersing into quenching oil for cooling for 20-30 minutes;
high-temperature tempering: placing the bit leg bearing subjected to integral quenching in a tempering furnace, heating to 570-590 ℃ under the protection of gas, preserving heat, and cooling to room temperature after discharging;
surface induction quenching: placing the palm bearing subjected to high-temperature tempering on high-frequency induction quenching equipment, and moving the palm bearing and the induction coil at a relative speed of 2-4mm/s under the power of 5-7KHz so as to ensure that the depth of an induction quenching hardened layer is higher than that of a carburized layer;
low-temperature tempering: and (3) placing the bearing of the palm of teeth after finishing the surface induction quenching in a tempering furnace, heating to 180-200 ℃, preserving heat, and cooling to room temperature after discharging.
2. The heat treatment method for the low-carbon low-alloy steel bit leg bearing casting according to claim 1, characterized in that: the temperature of the bulk quenching was 880 ℃.
3. The heat treatment method for the low-carbon low-alloy steel bit leg bearing casting according to claim 1, characterized in that: the temperature of the first tempering was 580 ℃.
4. The heat treatment method for the low-carbon low-alloy steel bit leg bearing casting according to claim 1, characterized in that: the low temperature tempering temperature is 190 ℃.
5. The heat treatment method for the low-carbon low-alloy steel bit leg bearing casting according to claim 1, characterized in that: the carburizing treatment includes:
a. carrying out strong infiltration treatment on the bearing of the bit leg under the conditions of carburizing atmosphere with the carbon concentration of 1.20-1.30% and the temperature of 920-;
b. c, performing diffusion treatment on the bearing of the bit leg treated in the step a under the carburizing atmosphere with the carbon concentration of 0.90-1.10% and at the temperature of 890-910 ℃;
c. and c, cooling the palm bearing treated in the step b to below 300 ℃ in a protective atmosphere, and air-cooling to room temperature after discharging.
6. The heat treatment method for a low-carbon low-alloy steel bit leg bearing casting according to claim 1 or 5, characterized in that: the carburizing agent adopted by the carburizing atmosphere is any one or more of methanol, ethane, propane, ethanol, propanol and ethyl acetate.
7. The heat treatment method for the low-carbon low-alloy steel bit leg bearing casting according to claim 1, characterized in that: and a cleaning step is also arranged between the integral quenching step and the high-temperature tempering step, the cleaning solution adopted in the cleaning step is 100 +/-10 ℃, and the cleaning time is 0.5-1.5 hours.
8. The heat treatment method for the low-carbon low-alloy steel bit leg bearing casting according to claim 1, characterized in that: the low-carbon low-alloy steel bit leg bearing is made of ZG20CrNiMo alloy and comprises the following components in percentage by weight: 0.17% -0.21% of C; 0.9% -1.1% of Cr; 0.6% -0.9% of Ni; 0.25% -0.35% of Mo; 0.60-0.90% Mn; 0.17% -0.37% of Si; less than or equal to 0.025 percent of S; p is less than or equal to 0.025 percent; cu less than or equal to 0.20 percent, and the balance being Fe.
9. The heat treatment method for the low-carbon low-alloy steel bit leg bearing casting according to claim 1, characterized in that: and (3) spraying water at 20-50 ℃ from the rear side of the induction coil, and synchronously and uninterruptedly spraying and quenching the heated part on the bearing of the bit leg until the surface induction quenching is finished.
10. A low-carbon low-alloy steel bit leg bearing is characterized in that: the cast product is prepared by the heat treatment method of the low-carbon low-alloy steel bit leg bearing casting part as claimed in any one of claims 1 to 9.
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| KR20040043324A (en) * | 2002-11-18 | 2004-05-24 | 에프에이지베어링코리아유한회사 | steel for bearing and heat treatment method thereof |
| US20050257860A1 (en) * | 2004-05-24 | 2005-11-24 | Takemori Takayama | Rolling member and producing method thereof |
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| CN108118283A (en) * | 2017-12-25 | 2018-06-05 | 南京工程学院 | A kind of surface peening heat treatment method for improving hardness gradient |
| CN108588388A (en) * | 2018-05-22 | 2018-09-28 | 武汉钢铁重工集团有限公司 | A kind of heat treatment method for gear wheel |
| CN110564922A (en) * | 2019-09-19 | 2019-12-13 | 北京科技大学 | Improved quenching process for steel for gear wheel |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20040043324A (en) * | 2002-11-18 | 2004-05-24 | 에프에이지베어링코리아유한회사 | steel for bearing and heat treatment method thereof |
| US20050257860A1 (en) * | 2004-05-24 | 2005-11-24 | Takemori Takayama | Rolling member and producing method thereof |
| CN103352111A (en) * | 2013-06-24 | 2013-10-16 | 湖北鸣利来冶金机械科技有限公司 | Heat treatment method for tricone bit claw |
| CN108118283A (en) * | 2017-12-25 | 2018-06-05 | 南京工程学院 | A kind of surface peening heat treatment method for improving hardness gradient |
| CN108588388A (en) * | 2018-05-22 | 2018-09-28 | 武汉钢铁重工集团有限公司 | A kind of heat treatment method for gear wheel |
| CN110564922A (en) * | 2019-09-19 | 2019-12-13 | 北京科技大学 | Improved quenching process for steel for gear wheel |
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