CN114574683B - 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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- CN114574683B CN114574683B CN202210178176.0A CN202210178176A CN114574683B CN 114574683 B CN114574683 B CN 114574683B CN 202210178176 A CN202210178176 A CN 202210178176A CN 114574683 B CN114574683 B CN 114574683B
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- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 58
- 238000010438 heat treatment Methods 0.000 title claims abstract description 49
- 238000000034 method Methods 0.000 title claims abstract description 36
- 238000005266 casting Methods 0.000 title claims abstract description 32
- 229910000851 Alloy steel Inorganic materials 0.000 title claims abstract description 23
- 238000010791 quenching Methods 0.000 claims abstract description 70
- 230000000171 quenching effect Effects 0.000 claims abstract description 65
- 238000005496 tempering Methods 0.000 claims abstract description 54
- 230000006698 induction Effects 0.000 claims abstract description 50
- 238000005255 carburizing Methods 0.000 claims abstract description 40
- 239000000956 alloy Substances 0.000 claims abstract description 6
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 42
- 238000001816 cooling Methods 0.000 claims description 38
- 238000007599 discharging Methods 0.000 claims description 27
- 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
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 230000001681 protective effect Effects 0.000 claims description 4
- 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
- 229910052804 chromium Inorganic materials 0.000 claims description 3
- 238000009792 diffusion process Methods 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 229910052750 molybdenum Inorganic materials 0.000 claims description 3
- 229910052759 nickel Inorganic materials 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
- 239000007921 spray Substances 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 2
- 238000005507 spraying Methods 0.000 claims description 2
- 239000011159 matrix material Substances 0.000 abstract description 8
- 239000010410 layer Substances 0.000 description 27
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 25
- 230000000052 comparative effect Effects 0.000 description 16
- 239000000463 material Substances 0.000 description 13
- 229910052757 nitrogen Inorganic materials 0.000 description 13
- 238000005096 rolling process Methods 0.000 description 6
- 238000005242 forging Methods 0.000 description 5
- 230000008595 infiltration Effects 0.000 description 5
- 238000001764 infiltration Methods 0.000 description 5
- 238000004321 preservation Methods 0.000 description 5
- 238000005553 drilling Methods 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 compound 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
- 238000010586 diagram Methods 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 229910001339 C alloy Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 125000004432 carbon atom Chemical group C* 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
- 238000005552 hardfacing Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 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
- 238000005457 optimization Methods 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- 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
-
- 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
-
- 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
-
- 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
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
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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: carrying out overall quenching after carburizing treatment on an as-cast bit leg bearing, carrying out high-temperature tempering at 570-590 ℃, and then placing the bit leg bearing subjected to high-temperature tempering on high-frequency induction quenching equipment, wherein the bit leg bearing and an induction coil move at a relative speed of 2-4mm/s under the power of 5-7KHz so as to ensure that the depth of an induction hardening layer of the induction hardening layer is higher than that of a carburized layer; finally, tempering at 180-200 ℃, the method solves the problem that the low-carbon low-alloy bit leg bearing casting cannot achieve both the plastic toughness and the surface wear resistance of the matrix, ensures the plastic property and the toughness of the cast low-carbon low-alloy bit leg bearing matrix, ensures better service performance when being acted by complex impact load, obviously improves the hardness and the depth of a hardening 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 very wide drilling tool for petroleum drilling, and the bit leg bearing is made of a low-carbon alloy forging material conventionally and manufactured by using a quenching and low-temperature tempering heat treatment process after carburization, so that the high hardness, high wear resistance and high matrix toughness of the surface of the bit leg bearing are ensured. For some special-structure bit leg bearings, a casting process can be used when the design structure cannot be realized by forging or the cost is too high. However, the casting material has no rolling and forging compression process compared with the forging material, and too coarse grains and structures lead to larger brittleness of the material.
At present, the material for the bearing of the bit leg is mainly low-carbon low-alloy steel, the representative mark is ZG20CrNiMo, and the main component is C:0.17-0.21%; cr:0.9-1.1%; ni:0.6-0.9%; mo:0.25-0.35%; mn:0.60-0.90%; si:0.17-0.37%. S is less than or equal to 0.025 percent; p less than or equal to 0.025%; less than or equal to 0.20 percent of Cu and the balance of Fe. When the material is used for a bit leg bearing, the conventional low-temperature tempering heat treatment process for carburizing and quenching the forging material is adopted, so that the toughness of the bit leg bearing matrix is too low to meet the performance requirement of SY/T5164 tricone bit on cast bit legs. In the prior art, a tempering heat treatment process is generally adopted to improve the plasticity and toughness of a casting material matrix, but the depth and hardness of a hardening layer on the surface of a bit leg bearing can not meet the performance requirements of products when the tempering process is adopted, namely, the requirements of cast bit leg products on the plastic toughness and the performance of the hardening layer on the surface of the core of the bit leg bearing can not be met at the same time 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 traditional low-carbon low-alloy steel bit leg bearing casting cannot be considered, the invention provides a composite heat treatment process capable of effectively improving the hardness of a hardening layer on the surface of the low-carbon low-alloy steel bit leg bearing casting, the depth of the hardening layer and the plasticity and 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, comprising the following steps:
and (3) integral quenching: after carburizing the cast-state bit leg bearing, placing the cast-state bit leg bearing in a quenching furnace, heating to 870-890 ℃ under a carburizing atmosphere with the carbon concentration of 0.4% -0.6%, preserving heat, discharging, immersing in quenching oil, and cooling for 20-30 minutes;
high temperature tempering: placing the bearing leg bearing subjected to integral quenching in a tempering furnace, heating to 570-590 ℃ under a protective atmosphere, preserving heat, discharging, and air-cooling to room temperature;
surface induction hardening: placing the high-temperature tempered bit leg bearing on high-frequency induction quenching equipment, and moving the bit leg 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 hardening layer is higher than that of a carburized layer;
low temperature tempering: and (3) placing the bearing leg bearing with the surface induction quenching in a tempering furnace, heating to 180-200 ℃, preserving heat, discharging, and air-cooling to room temperature.
As a preferable mode of the above-mentioned technical scheme, the temperature of the whole quenching is 880 ℃.
Preferably, the temperature of the first tempering is 580 ℃.
As a preferable mode of the above technical scheme, the low-temperature tempering temperature is 190 ℃.
As a preferable aspect of the above-described aspect, the carburizing treatment includes:
a. carrying out strong permeation treatment on the bearing of the bit leg under the carburizing atmosphere with the carbon concentration of 1.20% -1.30% and the temperature of 920-940 ℃;
b. c, performing diffusion treatment on the bearing leg treated in the step a under the carburizing atmosphere with the carbon concentration of 0.90% -1.10% and the temperature of 890-910 ℃;
c. and d, cooling the bearing leg treated in the step b to below 300 ℃ under the protective atmosphere, discharging, and then cooling to room temperature in an air way.
As the preferable technical scheme, the carburizing agent adopted in the carburizing atmosphere is one or more of methanol, ethane, propane, ethanol, propanol and ethyl acetate.
As the optimization of the technical scheme, a cleaning step is further arranged between the integral quenching step and the high-temperature tempering step, the cleaning liquid adopted in the cleaning step is 100+/-10 ℃, and the cleaning time is 0.5-1.5 hours.
As the preferable material of the technical scheme, the low-carbon low-alloy steel bit leg bearing is ZG20CrNiMo alloy, and comprises the following components in percentage by weight: 0.17% -0.21% of C;0.9% -1.1% Cr;0.6% -0.9% Ni;0.25% -0.35% Mo;0.60% -0.90% Mn;0.17% -0.37% Si; s is less than or equal to 0.025 percent; p less than or equal to 0.025%; less than or equal to 0.20 percent of Cu and the balance of Fe.
As the preferable scheme, the coil sprays water with the temperature of 20-50 ℃ on the rear side of the induction coil, and continuously spray-quenching is synchronously carried out on the heated part until the surface induction quenching is completed.
Preferably, the protective atmosphere is nitrogen.
In a second aspect, the invention provides a low carbon low alloy steel 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 casting of the low-carbon low-alloy steel bit leg bearing cannot consider both the plasticity and the toughness of the matrix and the surface wear resistance, and ensures the plasticity and the toughness of the matrix of the casting of the low-carbon low-alloy bit leg bearing, so that the casting has better service performance when being acted by complex impact load. In addition, the hardness and depth of the hard layer on the surface of the bit leg bearing are obviously improved, and the wear resistance of the bit leg bearing is greatly improved. In addition, the high-frequency induction quenching of the surface of the bit leg bearing can lead the surface of the bit leg bearing to form larger residual compressive stress, thereby improving the fatigue resistance of the bit leg bearing. In one aspect, for a rolling bit leg bearing, surface residual compressive stress can increase rolling bit leg bearing surface contact fatigue strength. On the other hand, for a sliding bit leg bearing, the surface residual compressive stress can reduce the detrimental effects of the sliding adhesion notch on fatigue performance. The usability of the bit leg bearing is greatly improved.
Drawings
FIG. 1 is a graph showing the microhardness gradients of the hardened layers of leg bearings prepared in accordance with examples of the present invention and comparative examples 1-3.
Fig. 2 is a schematic diagram of an arrangement of bit leg bearings during surface induction hardening according to an embodiment of the present invention.
Fig. 3 is a phase diagram of a hard facing layer of a bit leg bearing made in accordance with an embodiment of the present invention.
Fig. 4 is a diagram of the core metal phase of a bit leg bearing made in accordance with an embodiment of the present invention.
Detailed Description
For a better understanding of the present invention, the following examples are further illustrative of the present invention, but the contents of the present invention are not limited to the following examples only.
The as-cast bit leg bearings carburized in the examples and comparative examples of the present invention were cast by a conventional casting process and machined to a material grade ZG20CrNiMo, with typical compositions in weight percent: 0.17-0.21% C;0.9-1.1% Cr;0.6-0.9% Ni;0.25-0.35% Mo;0.60-0.90% Mn;0.17-0.37% Si; s is less than or equal to 0.025 percent; p less than or equal to 0.025%; less than or equal to 0.20 percent of Cu and the balance of Fe. However, the material of the bit leg bearing in the present invention is not limited thereto, and other low carbon and low alloy materials may be used.
The method for carrying out heat treatment on the bit leg bearing casting with the material grade of ZG20CrNiMo comprises the following steps:
carburizing: placing the cast-state bit leg bearing in a carburizing furnace, and performing carburizing treatment under a carburizing atmosphere with the carbon concentration of 0.90-1.30%;
and (3) integral quenching: placing the carburized bit leg bearing in a quenching furnace with controllable atmosphere, heating to 870-890 ℃ in the atmosphere with the carbon concentration of 0.4-0.6%, preserving heat, immediately immersing in quenching oil after discharging from the furnace, and cooling for 20-30 minutes;
high temperature tempering: placing the integrally quenched bit leg bearing in a tempering furnace, heating to 570-590 ℃ under the protection of nitrogen, preserving heat, discharging, and air-cooling to room temperature;
surface induction hardening: and (3) placing the high-temperature tempered bit leg bearing on induction quenching equipment, and enabling the bit leg bearing and an induction coil to move at a relative speed of 2-4mm/s under the power of 5-7KHz, and synchronously spraying water to cool the coil until surface quenching is finished. The adoption of 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 bearing leg bearing with the surface induction quenching in a tempering furnace, heating to 180-200 ℃, preserving heat, discharging, and air-cooling to room temperature.
According to the technical scheme provided by the embodiment of the invention, the carburization treatment process for the as-cast bit leg bearing with the material brand ZG20CrNiMo comprises the following steps:
a. placing the cast-state bit leg bearing in a carburizing furnace, and performing strong carburizing treatment under the carburizing atmosphere with the carbon concentration of 1.20-1.30% and the temperature of 920-940 ℃;
b. c, performing diffusion treatment on the bearing leg treated in the step a under the carburizing atmosphere with the carbon concentration of 0.90-1.10% and the temperature of 890-910 ℃;
c. b, cooling the bearing leg treated in the step b to below 300 ℃ in a nitrogen protection atmosphere, discharging the bearing leg, and cooling to room temperature in an air way;
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%. In the step c, nitrogen with the purity of 99.8% is filled in a cooling device to cool the bit leg bearing. 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 infiltration process, wherein carbon atoms can be fully diffused to the surface of the bit leg bearing, so that a carburized layer with a certain depth is formed on the surface; step b, reducing the carbon concentration in the carburizing atmosphere, so that the carbon gradient of the carburized layer of the bit leg bearing is more gentle, 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 microcrack formation on the near surface of the bit leg bearing 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 carburization, the bit leg bearing is subjected to integral quenching: and (3) placing the carburized bit leg bearing in a quenching furnace, heating to 870-890 ℃, keeping the temperature, discharging, immersing in quenching oil, and cooling for 20-30 minutes, wherein the stirring speed of the quenching oil is 800-900 revolutions per minute. The carbon concentration is maintained when the quenching and the heat preservation are ensured, and the decarburization in the quenching and the heat preservation process of the carburized surface can be reduced.
After the integral quenching, the bearing of the bit leg is subjected to high-temperature tempering treatment, and is put into a box tempering furnace to be tempered at high temperature under the protection of nitrogen. The high-temperature tempering heat preservation temperature is 570-590 ℃, and the high-temperature tempering heat preservation is finished, and the furnace outlet air cooling is finished. The integral quenching and high temperature tempering treatment improves the plasticity and toughness of the core part of the bit leg. At the moment, the core metallographic phase of the bit leg bearing mainly comprises tempered sorbite and ferrite tissues, the metallographic phase of the carburized layer mainly comprises tempered sorbite, and a certain amount of residual austenite exists.
After high-temperature tempering, the bit leg bearing is subjected to high-frequency induction quenching on the carburized layer surface layer. The induction coil is 3-5mm away from the outer circle surface of the bit leg bearing, the heating frequency is 5-7KHz, and the coil and the bit leg bearing relatively move at the speed of 2-4 mm/s. Meanwhile, tap water at 20-50 ℃ is sprayed from the coil at the rear side of the induction coil, and the heated part on the bit leg bearing is subjected to uninterrupted spray quenching synchronously until the surface induction quenching heating is completed. The depth of the surface induction quenching hardening layer is ensured to be higher than that of the carburized layer by controlling the power and the moving speed, so that the hardness of the hardening layer changes in a gradient way along with the gradient change of carbon.
And after the surface induction quenching is finished, carrying out low-temperature tempering on the bit leg bearing. The low-temperature tempering and heat preserving temperature is 180-190 ℃, and the heat preserving is finished and the furnace outlet air cooling is carried out.
In the carburizing treatment process, the carburizing heat-preserving time and the carbon concentration can be adjusted according to the requirement. The whole quenching, high temperature tempering and low temperature tempering heat preservation time can be determined according to the size of the bit leg bearing and the charging amount, and belongs to the conventional technical means of the person skilled in the art.
The effects of the present invention will be described below with reference to specific examples, but the scope of the present invention is not limited by the following examples.
Examples:
the embodiment provides a heat treatment method for a bit leg bearing casting 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 strong infiltration for 14.5 hours at the temperature of 930 ℃ under the atmosphere of which the carbon concentration is 1.25%;
b. c, diffusing the bearing leg treated in the step a for 3 hours at 900 ℃ in an atmosphere with the carbon concentration of 0.94%;
c. b, cooling the bearing leg treated in the step b to below 300 ℃ under the protection of nitrogen, and discharging and air cooling;
(2) Integral quenching treatment
Placing the carburized bit leg bearing in a quenching furnace with controllable atmosphere, heating to 880 ℃ in the atmosphere with the carbon concentration of 0.5%, preserving heat for 3 hours, discharging, immersing in quenching oil, and cooling for 30 minutes;
(3) High temperature tempering
Placing the integrally quenched bit leg bearing 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 leg bearing after the high temperature tempering is placed on the rotating shaft of the induction hardening apparatus, and the induction coil is disposed along the outer surface of the leg bearing and is stationary. The induction coil heating frequency was set to 6KHz and the rotational shaft rotational speed was set so that the bit leg bearing surface rotated relative to the induction coil at a speed of 3 mm/s. In the heating process, tap water at 20-30 ℃ is sprayed 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 leg bearing with the surface induction quenching in a tempering furnace, heating to 190 ℃, preserving heat for 4 hours, discharging and air cooling.
Comparative example 1
Unlike the examples, this comparative example was subjected to only the entire quenching treatment and the low-temperature tempering treatment after the carburizing treatment.
The heat treatment method of the bit leg 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 strong infiltration for 14.5 hours at the temperature of 930 ℃ under the atmosphere of which the carbon concentration is 1.25%;
b. c, diffusing the bearing leg treated in the step a for 3 hours at 900 ℃ in an atmosphere with the carbon concentration of 0.94%;
c. b, cooling the bearing leg treated in the step b to below 300 ℃ under the protection of nitrogen, and discharging and air cooling;
(2) Integral quenching treatment
Placing the carburized bit leg bearing in a quenching furnace with controllable atmosphere, heating to 880 ℃ in the atmosphere with the carbon concentration of 0.5%, preserving heat for 3 hours, discharging, immersing in quenching oil, and cooling for 30 minutes;
(3) Low temperature tempering
And (3) placing the bearing leg bearing subjected to integral quenching treatment in a tempering furnace, heating to 190 ℃, preserving heat for 4 hours, discharging and air cooling.
Comparative example 2
Unlike the examples, this comparative example was subjected to only the entire quenching treatment and the high-temperature tempering treatment after the carburizing treatment.
The heat treatment method of the bit leg 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 strong infiltration for 14.5 hours at the temperature of 930 ℃ under the atmosphere of which the carbon concentration is 1.25%;
b. c, diffusing the bearing leg treated in the step a for 3 hours at 900 ℃ in an atmosphere with the carbon concentration of 0.94%;
c. b, cooling the bearing leg treated in the step b to below 300 ℃ under the protection of nitrogen, and discharging and air cooling;
(2) Integral quenching treatment
Placing the carburized bit leg bearing in a quenching furnace with controllable atmosphere, heating to 880 ℃ in the atmosphere with the carbon concentration of 0.5%, preserving heat for 3 hours, discharging, immersing in quenching oil, and cooling for 30 minutes;
(3) High temperature tempering
And (3) placing the integrally quenched bit leg bearing in a tempering furnace, heating to 580 ℃ under the protection of nitrogen, preserving heat for 4 hours, discharging and air cooling.
Comparative example 3
Unlike the examples, the induction heating frequency of this comparative example was 15KHz.
The heat treatment method of the bit leg 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 strong infiltration for 14.5 hours at the temperature of 930 ℃ under the atmosphere of which the carbon concentration is 1.25%;
b. c, diffusing the bearing leg treated in the step a for 3 hours at 900 ℃ in an atmosphere with the carbon concentration of 0.94%;
c. b, cooling the bearing leg treated in the step b to below 300 ℃ under the protection of nitrogen, and discharging and air cooling;
(2) Integral quenching treatment
Placing the carburized bit leg bearing in a quenching furnace with controllable atmosphere, heating to 880 ℃ in the atmosphere with the carbon concentration of 0.5%, preserving heat for 3 hours, discharging, immersing in quenching oil, and cooling for 30 minutes;
(3) High temperature tempering
Placing the integrally quenched bit leg bearing 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 leg bearing after the high temperature tempering is placed on the rotating shaft of the induction hardening apparatus, and the induction coil is disposed along the outer surface of the leg bearing and is stationary. The induction coil heating frequency was set at 15KHz and the rotational shaft rotational speed was set so that the bit leg bearing surface rotated relative to the induction coil at a speed of 3 mm/s. In the heating process, tap water at 20-30 ℃ is sprayed 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 leg bearing with the surface induction quenching in a tempering furnace, heating to 190 ℃, preserving heat for 4 hours, discharging and air cooling.
Sample testing was performed on the heat treated leg bearings of examples and comparative examples 1-3, with specific sample results shown in Table 1.
TABLE 1 plasticity and toughness of bit leg bearing substrates after heat treatment of examples and comparative examples of the present invention
The results of fig. 1 show that the hardness and depth of the hardened layer of an as-cast bit leg bearing is higher than the bit leg bearing surface of a conventional bit leg bearing carburization + bulk quench + low temperature tempering process (comparative example 1). Referring to table 1 in fig. 1, after the heat treatment of carburization, integral quenching and high temperature tempering, the base of the bit leg bearing in comparative example 2 has plasticity and toughness comparable to those of the example, but the hardness of the hardened layer of the bit leg bearing surface is too low, which greatly reduces the wear resistance of the bit leg bearing. In addition, fig. 1 also shows that, when the induction hardening layer cannot completely cover the carburized layer (comparative example 3) during the surface induction hardening process after carburization, integral quenching and high temperature tempering, a steep drop in hardness occurs at the induction hardening layer and non-induction hardening interface, and when the hardness is distributed on the bearing surface of the bit leg, early cracking and flaking occur on the bearing surface of the bit leg during use. Particularly when applied to rolling bit leg bearings, rolling fatigue failure of the bit leg bearing can be easily caused if the interface occurs at the maximum dynamic shear stress used by the rolling bearing. That is, by adopting the heat treatment process, the problem of insufficient toughness of the base body of the bit leg bearing casting is solved, and meanwhile, the depth and the hardness of a hardening layer on the surface of the bit leg bearing casting can be remarkably improved, and the wear resistance and the fatigue resistance of the bit leg bearing are further improved.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (10)
1. The heat treatment method of the low-carbon low-alloy steel bit leg bearing casting is characterized by comprising the following steps of:
and (3) integral quenching: after carburizing the cast-state bit leg bearing, placing the cast-state bit leg bearing in a quenching furnace, heating to 870-890 ℃ under a carburizing atmosphere with the carbon concentration of 0.4% -0.6%, preserving heat, discharging, immersing in quenching oil, and cooling for 20-30 minutes;
high temperature tempering: placing the bearing of the bit leg subjected to integral quenching in a tempering furnace, heating to 570-590 ℃ under the protection of gas, preserving heat, discharging, and air-cooling to room temperature;
surface induction hardening: placing the high-temperature tempered bit leg bearing on high-frequency induction quenching equipment, and moving the bit leg 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 hardening layer is higher than that of a carburized layer;
low temperature tempering: and (3) placing the bearing leg bearing with the surface induction quenching in a tempering furnace, heating to 180-200 ℃, preserving heat, discharging, and air-cooling to room temperature.
2. The method for heat treating a low carbon low alloy steel bit leg bearing casting of claim 1, wherein: the overall quench temperature was 880 ℃.
3. The method for heat treating a low carbon low alloy steel bit leg bearing casting of claim 1, wherein: the temperature of the first tempering was 580 ℃.
4. The method for heat treating a low carbon low alloy steel bit leg bearing casting of claim 1, wherein: the low temperature tempering temperature was 190 ℃.
5. The method for heat treating a low carbon low alloy steel bit leg bearing casting of claim 1, wherein: the carburizing treatment includes:
a. carrying out strong permeation treatment on the bearing of the bit leg under the carburizing atmosphere with the carbon concentration of 1.20% -1.30% and the temperature of 920-940 ℃;
b. c, performing diffusion treatment on the bearing leg treated in the step a under the carburizing atmosphere with the carbon concentration of 0.90% -1.10% and the temperature of 890-910 ℃;
c. and d, cooling the bearing leg treated in the step b to below 300 ℃ under the protective atmosphere, discharging, and then cooling to room temperature in an air way.
6. The method for heat treating a low carbon low alloy steel bit leg bearing casting according to claim 1 or 5, characterized by: the carburizing agent adopted in the carburizing atmosphere is any one or more of methanol, ethane, propane, ethanol, propanol and ethyl acetate.
7. The method for heat treating a low carbon low alloy steel bit leg bearing casting of claim 1, wherein: a cleaning step is further arranged between the integral quenching step and the high-temperature tempering step, wherein the cleaning liquid adopted in the cleaning step is 100+/-10 ℃, and the cleaning time is 0.5-1.5 hours.
8. The method for heat treating a low carbon low alloy steel bit leg bearing casting of claim 1, wherein: 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% Cr;0.6% -0.9% Ni;0.25% -0.35% Mo;0.60% -0.90% Mn;0.17% -0.37% Si; s is less than or equal to 0.025 percent; p less than or equal to 0.025%; less than or equal to 0.20 percent of Cu and the balance of Fe.
9. The method for heat treating a low carbon low alloy steel bit leg bearing casting of claim 1, wherein: and spraying water at 20-50 ℃ to the rear side of the induction coil, and synchronously carrying out uninterrupted spray quenching on the heated part of the bit leg bearing until the surface induction quenching is completed.
10. The utility model provides a low carbon low alloy steel leg bearing which characterized in that: prepared by the heat treatment method of the low carbon low alloy steel leg bearing castings according to 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 |
| 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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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP5319866B2 (en) * | 2004-05-24 | 2013-10-16 | 株式会社小松製作所 | Rolling member and manufacturing method thereof |
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| 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 |
| 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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