CN110592524A - Three-stage type carbon-nitrogen-boron ternary gas deep layer co-cementation method for low carbon nickel-molybdenum steel - Google Patents

Three-stage type carbon-nitrogen-boron ternary gas deep layer co-cementation method for low carbon nickel-molybdenum steel Download PDF

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CN110592524A
CN110592524A CN201910978299.0A CN201910978299A CN110592524A CN 110592524 A CN110592524 A CN 110592524A CN 201910978299 A CN201910978299 A CN 201910978299A CN 110592524 A CN110592524 A CN 110592524A
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permeation
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CN110592524B (en
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付甲
魏胜利
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Xian Shiyou University
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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
    • C23C8/40—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 liquids, e.g. salt baths, liquid suspensions
    • C23C8/42—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 liquids, e.g. salt baths, liquid suspensions only one element being applied
    • 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
    • C23C8/40—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 liquids, e.g. salt baths, liquid suspensions
    • C23C8/42—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 liquids, e.g. salt baths, liquid suspensions only one element being applied
    • C23C8/44—Carburising
    • C23C8/46—Carburising of ferrous surfaces
    • 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
    • C23C8/40—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 liquids, e.g. salt baths, liquid suspensions
    • C23C8/52—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 liquids, e.g. salt baths, liquid suspensions more than one element being applied in one step
    • C23C8/54—Carbo-nitriding
    • C23C8/56—Carbo-nitriding of ferrous surfaces
    • 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
    • C23C8/40—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 liquids, e.g. salt baths, liquid suspensions
    • C23C8/58—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 liquids, e.g. salt baths, liquid suspensions more than one element being applied in more than one step

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Abstract

The three-stage C-N-B ternary gas deep layer co-cementation method of low carbon Ni-Mo steel is characterized by that the low carbon Ni-Mo steel is respectively placed in carburizing furnace, and the co-cementation agent formed from kerosene, anhydrous methanol, liquid ammonia gas, boric acid and lanthanum oxide is added, and under the action of catalyst of lanthanum oxide, etc. by means of chemical heat treatment method and adopting three-stage ternary gas co-cementation process, the fine needle-like martensite, nitride and boride on the surface can be finally obtained, so that the hardness and wear resistance of the component can be greatly raised; the method has low cost and simple and controllable process, and provides technical support for producing the high-strength and high-wear-resistance surface modified drill bit, thereby having wide application prospect in the fields of precision machining, national defense industry, oil drilling and the like.

Description

Three-stage type carbon-nitrogen-boron ternary gas deep layer co-cementation method for low carbon nickel-molybdenum steel
Technical Field
The invention relates to the field of new materials, in particular to a three-stage carbon-nitrogen-boron ternary gas deep layer co-cementation method for low-carbon nickel-molybdenum steel.
Background
The drill bit is an important tool for petroleum drilling, the drill bit for petroleum drilling plays a role in impacting, crushing and shearing and breaking stratum rocks when rotating, the quality of the working performance of the drill bit directly influences the drilling quality, the drilling efficiency and the drilling cost, and the traditional carburization process can not be met gradually.
In recent years, researchers have done a lot of work on the synthesis and preparation of boron-carbon-nitrogen materials, and the ternary co-cementation has been the basis of related research. For example, China with publication number CN1442504AThe patent application CN02109879.4 discloses that solid boron-supplying agent is placed in a carburizing furnace and separated from a workpiece, and simultaneously carbon and nitrogen co-permeation liquid is respectively dripped into the carburizing furnace to form boron, carbon and nitrogen ternary gas phase co-permeation, the co-permeation temperature is 750-870 ℃, the co-permeation speed is 0.15-0.2 mm/h, and the furnace is taken out and oil cooling or water cooling is carried out. The patented technology only considers that the thickness of a carburized layer is only 0.3mm in a low-temperature co-carburization lower shallow layer co-carburization technology, mainly carburization (C) and nitridation (N), and the infiltration amount of boron (B) is seriously insufficient at low temperature, so that the impact toughness performance index is influenced, and the use requirements of high-hardness high-wear resistance and high-impact resistance working condition parts such as oil drilling bits and the like cannot be met. The low-carbon nickel-molybdenum steel (such as 20 Ni) which can be searched can be browsed at present3Mo，20Ni4Mo, etc.) the thickness of the co-cementation layer which can only be obtained by the carbonitriding and boronizing technology is less than 0.7mm, and compared with the deep layer N-cementation technology (the total depth is about 1 mm) in Europe and America, the deep layer N-cementation or the co-cementation technology in China is insufficient.
Disclosure of Invention
Aiming at the current situation of the prior art, the invention aims to provide a three-stage carbon-nitrogen-boron ternary gas deep layer co-cementation method, which is used for obtaining a deep layer co-cementation layer by adopting a three-stage ternary co-cementation method for controlling temperature and time in stages aiming at low-carbon nickel-molybdenum steel, wherein the thickness of a N-cementation layer can reach 0.75-1.2 mm, so that the fatigue life and the impact toughness of the low-carbon nickel-molybdenum steel are remarkably improved, and the requirements of deep layer N-cementation of parts such as oil drill bits and the like can be met.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the three-stage type carbon-nitrogen-boron ternary gas deep layer co-cementation method of the low-carbon nickel-molybdenum steel comprises the following steps of:
(1) preparing a boron donor, uniformly mixing, bonding and drying 2-3% of lanthanum oxide rare earth, 5-15% of boron carbide, 15% of potassium fluoborate and the balance of silicon carbide into solid blocks according to weight percentage; in addition, preparing a carbonitriding solution, wherein the carbonitriding solution consists of 50% of carbamide, 40% of sodium carbonate and 10% of sodium chloride in percentage by mass;
(2) placing a low-carbon nickel-molybdenum steel drill bit workpiece to be treated in a drop-controlled carburizing furnace, heating to 860 ℃, and exhausting for 1 hour;
(3) three-stage co-permeation process for gas ternary deep layer co-permeation
3.1, in the first stage, carburizing is mainly carried out, and the carburization is carried out after heat preservation is carried out for 2 hours at the initial heating temperature of 860 ℃, wherein 40 drops/minute of methanol, 160 drops/minute of kerosene and 120 materials, the content of sulfur in the kerosene is less than 0.04 percent, the furnace pressure is 25-35mm Hg, the time of the strong infiltration period is 5-8 hours, the diffusion period is 3-6 hours, and the infiltration speed is 0.18-0.25 mm/hour;
3.2, simultaneously carrying out carburizing and boronizing on the basis of the carburizing in the first stage, adding the solid boron donor prepared in the first stage and sodium fluoride with the mass fraction of 40% into the furnace atmosphere to carry out carborundum co-permeation, wherein the adding amount is as follows: 30g/h of sodium fluoride and 40g/h of boron supply agent, and dripping 10% of boric acid by mass at a dripping speed of 40 drops/min; or adding 50g-60g of boric acid solution into each liter of methanol mixed solution in the first stage, controlling the using amount of boric acid to be 0.83g/min-1g/min, controlling the carborundum co-permeation period to be 1h, then continuously heating to 920 ℃ on the basis of the original 860 ℃, and preserving heat for 10 h;
3.3, the third stage is mainly carburizing and nitriding, the temperature is reduced from 920 ℃ to 870-880 ℃ from the second stage, the temperature is kept for 6h, the carbonitriding liquid prepared in the first stage is introduced into the furnace atmosphere of the second stage, the dropping speed is 4-6 ml/min, and in addition, 0.03m of carbonitriding liquid is introduced3H pure nitrogen N2So as to improve the depth of the co-nitriding layer, or liquid ammonia is dripped into the co-nitriding layer at the dripping speed of 0.09 to 0.12 liter/h to improve the nitriding efficiency and the thickness of the co-nitriding layer;
(4) and cooling the co-permeation piece with the furnace or air cooling.
Compared with the prior art, the invention has the advantages that:
the thickness of the obtained carbonitriding layer is about 0.75-1.2 mm, and the obtained carbonitriding piece has good hardness, wear resistance and fatigue resistance.
According to the invention, through a three-stage ternary co-cementation process, in the first stage, carburization is mainly used (the mass percent of carbon content is 0.8-1.6%), and a carbide network is prevented from appearing; in the second stage, carburizing and boronizing are mainly carried out (wherein the mass percentage of boron content is 0.02-0.04%), so that the impact toughness and the bending fatigue resistance are greatly improved; in the third stage, carburizing and nitriding are mainly performed (wherein the mass percent of nitrogen content is 0.3-0.5%), and the red hardness is greatly improved. The method is suitable for low-carbon nickel-molybdenum steel wear-resistant parts or cutter parts with high requirements on wear resistance and impact toughness of a hardness meter, the hardness, wear resistance and fatigue life of the workpiece are obviously improved, the penetrant is simple to prepare, and the equipment and process are simple.
By adopting the three-section ternary co-cementation method, the fatigue life of the low-carbon nickel-molybdenum steel can be greatly prolonged, compared with the traditional carburization process, the service life is prolonged by more than 2 times, the hardness is improved by more than 3HRC, and the impact toughness is also improved by more than 1 time. The drill bit after surface modification by the three-stage co-permeation method has wide application prospect in the fields of precision machining, national defense industry, oil drilling and the like.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Example one
The embodiment comprises the following steps:
(1) preparing a boron supply agent, namely uniformly mixing, bonding and drying 2% of lanthanum oxide rare earth, 5% of boron carbide, 15% of potassium fluoborate and the balance of silicon carbide into solid blocks according to the weight percentage; in addition, preparing a carbonitriding solution, wherein the carbonitriding solution consists of 50% of carbamide, 40% of sodium carbonate and 10% of sodium chloride in percentage by mass;
(2) 20Ni to be treated4Placing the Mo steel drill bit workpiece in a drop-controlled carburizing furnace, heating to 860 ℃, and exhausting for 1 hour;
(3) three-stage co-permeation process for gas ternary deep layer co-permeation
3.1, the first stage is mainly carburization, and the carburization is carried out after the heat preservation is carried out for 2 hours at the initial heating temperature of 860 ℃, wherein the methanol is 40 drops/min, the kerosene is 120 drops/min, and the sulfur content of the kerosene is<0.04% to ensure carburization quality, 25mm Hg furnace pressure, and 20Ni with diameter less than 200mm4Mo Steel bit workpiece, Strong penetration time (t)1) 5-6 hours, diffusion period (t)1) 3-4 hours (see table 1 for details), the penetration rate is 0.18 mm/hour;
3.2, simultaneously carrying out carburizing and boronizing on the basis of the carburizing in the first stage, adding the solid boron donor prepared in the first stage and sodium fluoride with the mass fraction of 40% into the furnace atmosphere to carry out carborundum co-permeation, wherein the adding amount is as follows: 30g/h of sodium fluoride and 40g/h of boron supply agent, dripping 10% of boric acid by mass fraction at the dripping speed of 40 drops/min for 1h, continuously heating to 920 ℃ on the basis of 860 ℃, and preserving heat for 10 h;
3.3, the third stage is mainly carburizing and nitriding, the temperature is reduced from 920 ℃ to 870 ℃ in the second stage, and the temperature is preserved (t)3) Introducing the carbonitriding solution prepared in the first step into the second-stage furnace atmosphere for 6h, wherein the dropping speed is 4 ml/min, and 0.03m is introduced3H pure nitrogen N2The depth of the co-nitriding layer is improved, and the dropping speed is 0.09 liter/h to improve the nitriding efficiency and the thickness of the co-nitriding layer;
(4) and cooling the co-permeation piece with the furnace or air cooling.
The parameters selected in the steps are selected to be lower values within the range of application parameters, the temperature of the third-stage co-permeation is 870 ℃, a deeper ternary co-permeation layer with the carbon content of 0.81%, the nitrogen content of 0.177% and the boron content of 0.034% is obtained, and the thickness of the ternary co-permeation layer is about 0.95-1.15 mm. The hardness of the lower surface layer in the process is measured to be 1000-1150HV, the hardness of the carburized layer is still as high as 950HV when the thickness is 1mm, the wear resistance is improved by about 2.8-3 times compared with the carburization in the first stage, and the dispersion degree of carbide is higher at the moment. In addition, a ternary co-permeation layer with higher thickness is obtained, the nitride and the boride are dispersed and distributed, the thickness of the nitride layer is increased to 1.06mm, the fatigue life is prolonged by 18-20 times, and the comprehensive performance is greatly improved.
TABLE 1
And (3) filling, wherein a vent channel with the diameter of 80mm is reserved in the center of the basket material under the charging quantity.
Example two
The embodiment comprises the following steps:
(1) preparing a boron supply agent, namely uniformly mixing, bonding and drying 2% of lanthanum oxide rare earth, 5% of boron carbide, 15% of potassium fluoborate and the balance of silicon carbide into solid blocks according to the weight percentage; in addition, preparing a carbonitriding solution, wherein the carbonitriding solution consists of 50% of carbamide, 40% of sodium carbonate and 10% of sodium chloride in percentage by mass;
(2) 20Ni to be treated4Placing the Mo steel drill bit workpiece in a drop-controlled carburizing furnace, heating to 860 ℃, and exhausting for 1 hour;
(3) three-stage co-permeation process for gas ternary deep layer co-permeation
3.1, the first stage is mainly carburization, and the carburization is carried out after the heat preservation is carried out for 2 hours at the initial heating temperature of 860 ℃, wherein the methanol is 40 drops/min, the kerosene is 120 drops/min, and the sulfur content of the kerosene is<0.04% to ensure carburization quality, 25mm Hg furnace pressure, and 20Ni with diameter less than 200mm4Mo Steel bit workpiece, Strong penetration period (t)1) The time is 5-6 hours, and the diffusion period (t)1) 3-4 hours (see table 2 for details), the penetration rate is 0.18 mm/hour;
3.2, simultaneously carrying out carburizing and boronizing on the basis of the carburizing in the first stage, adding the solid boron donor prepared in the first stage and sodium fluoride with the mass fraction of 40% into the furnace atmosphere to carry out carborundum co-permeation, wherein the adding amount is as follows: 30g/h of sodium fluoride and 40g/h of boron supply agent are consumed and placed; in addition, in the first stage, 50g of boric acid solution is added into each liter of methanol mixed solution to control the boric acid dosage of 0.83g/min, the carborundum co-permeation period is 1h, then the temperature is continuously increased to 920 ℃ on the basis of the original 860 ℃, and the temperature is kept for 10 h;
3.3, the third stage is mainly carburizing and nitriding, the temperature is reduced from 920 ℃ to 870 ℃ in the second stage, and the temperature is preserved (t)3)6h, introducing the carbonitriding solution prepared in the first step into the atmosphere in the second-stage furnace, wherein the dropping speed is 4 ml/min, and liquid ammonia gas is added at the dropping speed of 0.09L/h, so as to improve the nitriding efficiency and the thickness of the carbonitriding layer;
(4) and cooling the co-permeation piece with the furnace or air cooling.
The parameters selected in the steps are selected to be lower values within the range of application parameters, the co-permeation temperature of the third stage is 870 ℃, a deeper ternary co-permeation layer with the carbon content of 0.80%, the nitrogen content of 0.175% and the boron content of 0.03% is obtained, and the thickness of the ternary co-permeation layer is about 0.75-1.1 mm. The hardness of the lower surface layer in the process is measured to be 1000-1100HV, the hardness of the carburized layer is still as high as 925HV when the thickness is 1mm, the wear resistance is improved by about 2.5-3 times compared with the carburization in the first stage, and the dispersion degree of carbide is higher at the moment. In addition, a ternary co-permeation layer with higher thickness is obtained, the nitride and the boride are dispersed and distributed, the thickness of the nitride layer is increased to 1.05mm, the fatigue life is prolonged by 17-20 times, and the comprehensive performance is greatly improved.
TABLE 2
And (3) filling, wherein a vent channel with the diameter of 80mm is reserved in the center of the basket material under the charging quantity.
EXAMPLE III
The embodiment comprises the following steps:
(1) preparing a boron donor, wherein the lanthanum oxide rare earth accounts for 2.5 percent, the boron carbide accounts for 10 percent, the potassium fluoborate accounts for 15 percent and the balance is silicon carbide, and the boron donor and the silicon carbide are uniformly mixed, bonded and dried into solid blocks; in addition, preparing a carbonitriding solution, wherein the carbonitriding solution consists of 50% of carbamide, 40% of sodium carbonate and 10% of sodium chloride in percentage by mass;
(2) 20Ni to be treated4Placing the Mo steel drill bit workpiece in a drop-controlled carburizing furnace, heating to 860 ℃, and exhausting for 1 hour;
(3) three-stage co-permeation process for gas ternary deep layer co-permeation
3.1, the first stage is mainly carburization, and the carburization is carried out after the heat preservation is carried out for 2 hours at the initial heating temperature of 860 ℃, wherein the methanol is 40 drops/minute, the kerosene is 140 drops/minute, and the sulfur content of the kerosene is<0.04% to ensure carburization quality, furnace pressure 30mm Hg, 20Ni with diameter less than 200mm4Mo Steel bit workpiece, Strong penetration period (t)1) The time is 5-6 hours, and the diffusion period (t)2) 3-4 hours (see Table 3 for details), the permeation rate is 0.21 mm/hour;
3.2, simultaneously carrying out carburizing and boronizing on the basis of the carburizing in the first stage, adding the solid boron donor prepared in the first stage and sodium fluoride with the mass fraction of 40% into the furnace atmosphere to carry out carborundum co-permeation, wherein the adding amount is as follows: 30g/h of sodium fluoride and 40g/h of boron supply agent, dripping 10% of boric acid by mass fraction at the dripping speed of 40 drops/min for 1h, continuously heating to 920 ℃ on the basis of the original 860 ℃, and preserving heat for 10 h;
3.3, the third stage is mainly carburizing and nitriding, the temperature is reduced to 875 ℃ from 920 ℃ in the second stage, and the temperature is kept (t)3)6h, introducing the carbonitriding solution prepared in the first step into the atmosphere in the second-stage furnace, wherein the dropping speed is 5 ml/min, and liquid ammonia gas is added at the dropping speed of 0.105 l/h so as to improve the nitriding efficiency and the thickness of the carbonitriding layer;
(4) and cooling the co-permeation piece with the furnace or air cooling.
Selecting an intermediate value within the range of the application parameters according to the parameters selected in the step, and obtaining a deeper ternary co-permeation layer with the carbon content of 0.81%, the nitrogen content of 0.178% and the boron content of 0.034% by adopting the co-permeation temperature of 875 ℃ in the third stage, wherein the thickness of the ternary co-permeation layer is about 1.0-1.2 mm by the method. The hardness of the lower surface layer in the process is measured to be 1000-1150HV, the hardness of the carburized layer is still as high as 965HV when the thickness is 1mm, the wear resistance is improved by about 2.5-3 times compared with the carburization in the first stage, and the dispersion degree of carbide is higher at the moment. In addition, a ternary co-permeation layer with higher thickness is obtained, the nitride and the boride are dispersed and distributed, the thickness of the nitride layer is increased to 1.06mm, the fatigue life is prolonged by 18-20 times, and the comprehensive performance is greatly improved.
TABLE 3
And (3) filling, wherein a vent channel with the diameter of 80mm is reserved in the center of the basket material under the charging quantity.
Example four
The embodiment comprises the following steps:
(1) preparing a boron supply agent, namely uniformly mixing 3% of lanthanum oxide rare earth, 15% of boron carbide, 15% of potassium fluoborate and the balance of silicon carbide, bonding and drying into solid blocks; in addition, preparing a carbonitriding solution, wherein the carbonitriding solution consists of 50% of carbamide, 40% of sodium carbonate and 10% of sodium chloride in percentage by mass;
(2) 20Ni to be treated4Placing the Mo steel drill bit workpiece in a drop-controlled carburizing furnace, heating to 860 ℃, and exhausting for 1 hour;
(3) three-stage co-permeation process for gas ternary deep layer co-permeation
3.1, the first stage is mainly carburization, and the carburization is carried out after the heat preservation is carried out for 2 hours at the initial heating temperature of 860 ℃, wherein the methanol is 40 drops/minute, the kerosene is 160 drops/minute, and the sulfur content of the kerosene is<0.04% to ensure carburization quality, furnace pressure 35mm Hg, 20Ni with diameter of 200mm-300mm4Mo Steel bit workpiece, Strong penetration period (t)1) Time 8 hours, diffusion period (t)2) 5-6 hours (see table 4 for details), the penetration rate is 0.25 mm/hour;
3.2, simultaneously carrying out carburizing and boronizing on the basis of the carburizing in the first stage, adding the solid boron donor prepared in the first stage and sodium fluoride with the mass fraction of 40% into the furnace atmosphere to carry out carborundum co-permeation, wherein the adding amount is as follows: 30g/h of sodium fluoride and 40g/h of boron supply agent, in addition, 60g of boric acid solution is added into each liter of methanol mixed liquor in the first stage to control the boric acid dosage of 1g/min, the carborundum co-permeation period is 1h, then the temperature is continuously increased to 920 ℃ on the basis of the original 860 ℃, and the temperature is kept for 10 h;
3.3, the third stage is mainly carburizing and nitriding, the temperature is reduced to 880 ℃ from 920 ℃ in the second stage, and the temperature is kept (t)3) Introducing the carbonitriding solution prepared in the first step into the second-stage furnace atmosphere for 6h, wherein the dropping speed is 5 ml/min, and 0.03m is introduced3H pure nitrogen N2The depth of the co-nitriding layer is increased, and the dropping speed is 0.12 liter/h to improve the nitriding efficiency and the thickness of the co-nitriding layer;
(4) and cooling the co-permeation piece with the furnace or air cooling.
The highest value in the application parameter range is selected according to the parameters selected in the steps, the co-permeation temperature of the third stage is 880 ℃, the deeper ternary co-permeation layer with the carbon content of 0.80%, the nitrogen content of 0.177% and the boron content of 0.033% is obtained, and the thickness of the ternary co-permeation layer is about 0.9-1.1 mm. The hardness of the lower surface layer in the process is measured to be 1000-1150HV, the hardness of the carburized layer is still as high as 965HV when the thickness is 1mm, the wear resistance is improved by about 2.5-3 times compared with the carburization in the first stage, and the dispersion degree of carbide is higher at the moment. In addition, a ternary co-permeation layer with higher thickness is obtained, the nitride and the boride are dispersed and distributed, the thickness of the nitride layer is increased to 1.05mm, the fatigue life is prolonged by 18-20 times, and the comprehensive performance is greatly improved.
TABLE 4
And (3) filling, wherein a vent channel with the diameter of 80mm is reserved in the center of the basket material under the charging quantity.
Comparative example:
this comparative example comprises the following steps:
(1) placing a 20Ni4Mo steel drill bit workpiece with the diameter of phi 100 mm-200 mm and a 20Ni3Mo steel drill bit workpiece with the diameter of phi 200mm-300mm to be processed into a dripping control carburizing furnace, heating to 860 ℃, and exhausting for 1 hour;
(2) will consist of kerosene (C)nH2nEtc.), anhydrous methanol (CH)3OH), liquid ammonia (NH)3) Isocomponent co-permeation agent (kerosene sulfur content in it)<0.04% to ensure the carburizing quality), continuously dripping into a carburizing furnace, charging and carburizing the surface layer of the drill bit, wherein carbon active atoms generated by decomposition due to heating reach certain atomic concentration;
(3) only mainly carburizing, and carrying out heat preservation for 2h at the initial heating temperature of 860 ℃ and then carburizing, wherein: methanol 40 drops/min, kerosene 140 drops/min (kerosene sulfur content)<0.04% to ensure carburization quality), a furnace pressure of 30mm Hg, 20Ni4Strong penetration period (t) of Mo bit1) 5-6 hours, diffusion period (t)2) Is 3-4 hours, 20Ni3Strong penetration period (t) of Mo bit1) 8 hours, diffusion period (t)2) 5-6 hours (see Table 5 for details), the penetration rate is 0.21 mm/hour;
(4) and after the steps are finished, cooling the co-permeation piece along with the furnace or air cooling.
After the steps are finished, the carbon content of the co-carburized layer is about 1.2%, and the thickness of the carburized layer is about 1.2-2.1 mm. The hardness of the surface layer in the step is only 880-890HV, the hardness of the carburized layer is about 600HV when the thickness of the carburized layer is 0.5mm away from the surface, the hardness of the carburized layer is about 400HV when the thickness of the carburized layer is 1mm away from the surface, the wear resistance is improved by about 1 time after carburization, and carbides are distributed in a net shape.
TABLE 5
And (3) filling, wherein a vent channel with the diameter of 80mm is reserved in the center of the basket material under the charging quantity.
Therefore, compared with the comparative example, the embodiment of the invention has the advantages that:
the thickness of the obtained carbonitriding layer is about 0.75-1.2 mm, and the obtained carbonitriding piece has good hardness, wear resistance and fatigue resistance.

Claims (1)

1. The three-stage type carbon-nitrogen-boron ternary gas deep layer co-cementation method of the low-carbon nickel-molybdenum steel is characterized by comprising the following steps of:
(1) preparing a boron donor, uniformly mixing, bonding and drying 2-3% of lanthanum oxide rare earth, 5-15% of boron carbide, 15% of potassium fluoborate and the balance of silicon carbide into solid blocks according to weight percentage; in addition, preparing a carbonitriding solution, wherein the carbonitriding solution consists of 50% of carbamide, 40% of sodium carbonate and 10% of sodium chloride in percentage by mass;
(2) placing a low-carbon nickel-molybdenum steel drill bit workpiece to be treated in a drop-controlled carburizing furnace, heating to 860 ℃, and exhausting for 1 hour;
(3) three-stage co-permeation process for gas ternary deep layer co-permeation
3.1, in the first stage, carburizing is mainly carried out, and the carburization is carried out after heat preservation is carried out for 2 hours at the initial heating temperature of 860 ℃, wherein 40 drops/minute of methanol, 160 drops/minute of kerosene and 120 materials, the content of sulfur in the kerosene is less than 0.04 percent, the furnace pressure is 25-35mm Hg, the time of the strong infiltration period is 5-8 hours, the diffusion period is 3-6 hours, and the infiltration speed is 0.18-0.25 mm/hour;
3.2, simultaneously carrying out carburizing and boronizing on the basis of the carburizing in the first stage, adding the solid boron donor prepared in the first stage and sodium fluoride with the mass fraction of 40% into the furnace atmosphere to carry out carborundum co-permeation, wherein the adding amount is as follows: 30g/h of sodium fluoride and 40g/h of boron supply agent, and dripping 10% of boric acid by mass at a dripping speed of 40 drops/min; or adding 50g-60g of boric acid solution into each liter of methanol mixed solution in the first stage, controlling the using amount of boric acid to be 0.83g/min-1g/min, controlling the carborundum co-permeation period to be 1h, then continuously heating to 920 ℃ on the basis of the original 860 ℃, and preserving heat for 10 h;
3.3, the third stage is mainly carburizing and nitriding, the temperature is reduced from 920 ℃ to 870-880 ℃ from the second stage, the temperature is kept for 6h, the carbonitriding liquid prepared in the first stage is introduced into the furnace atmosphere of the second stage, the dropping speed is 4-6 ml/min, and in addition, 0.03m of carbonitriding liquid is introduced3H pure nitrogen N2So as to improve the depth of the co-nitriding layer, or liquid ammonia is dripped into the co-nitriding layer at the dripping speed of 0.09 to 0.12 liter/h to improve the nitriding efficiency and the thickness of the co-nitriding layer;
(4) and cooling the co-permeation piece with the furnace or air cooling.
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JP2502405B2 (en) * 1990-07-31 1996-05-29 川崎製鉄株式会社 Continuous annealing furnace
CN1077231A (en) * 1992-04-07 1993-10-13 上海工程技术大学 Quick liquid carburizing compound of no cyanogen and carburization process
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