CN112301308A - Carbonitriding heat treatment method and alloy part prepared by same - Google Patents
Carbonitriding heat treatment method and alloy part prepared by same Download PDFInfo
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- 238000010438 heat treatment Methods 0.000 title claims abstract description 126
- 238000000034 method Methods 0.000 title claims abstract description 100
- 238000005256 carbonitriding Methods 0.000 title claims abstract description 65
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 28
- 239000000956 alloy Substances 0.000 title claims abstract description 28
- 239000007789 gas Substances 0.000 claims abstract description 69
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 48
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 48
- 239000012159 carrier gas Substances 0.000 claims abstract description 13
- 238000010521 absorption reaction Methods 0.000 claims abstract description 12
- 238000010791 quenching Methods 0.000 claims description 40
- 230000000171 quenching effect Effects 0.000 claims description 40
- 238000006243 chemical reaction Methods 0.000 claims description 34
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 28
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 25
- 238000004140 cleaning Methods 0.000 claims description 21
- 238000005496 tempering Methods 0.000 claims description 21
- 230000003647 oxidation Effects 0.000 claims description 14
- 238000007254 oxidation reaction Methods 0.000 claims description 14
- 239000001294 propane Substances 0.000 claims description 14
- 238000001816 cooling Methods 0.000 claims description 10
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 6
- 239000003350 kerosene Substances 0.000 claims description 3
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims description 3
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 claims description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 abstract description 15
- 229910000734 martensite Inorganic materials 0.000 abstract description 13
- 230000015572 biosynthetic process Effects 0.000 abstract description 8
- 238000012545 processing Methods 0.000 abstract description 3
- 239000012495 reaction gas Substances 0.000 abstract description 3
- 238000005336 cracking Methods 0.000 abstract 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 11
- 229910002091 carbon monoxide Inorganic materials 0.000 description 7
- 238000005255 carburizing Methods 0.000 description 6
- 239000003345 natural gas Substances 0.000 description 6
- 239000003921 oil Substances 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 229910001566 austenite Inorganic materials 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 239000004215 Carbon black (E152) Substances 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 4
- 229930195733 hydrocarbon Natural products 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 239000002737 fuel gas Substances 0.000 description 3
- 230000008595 infiltration Effects 0.000 description 3
- 238000001764 infiltration Methods 0.000 description 3
- 238000005457 optimization Methods 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- -1 hydrocarbon hydrogen chloride Chemical class 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 2
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 238000010407 vacuum cleaning Methods 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- LBPGGVGNNLPHBO-UHFFFAOYSA-N [N].OC Chemical compound [N].OC LBPGGVGNNLPHBO-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 238000006757 chemical reactions by type Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000000779 depleting effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000002156 mixing Methods 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
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/28—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 more than one element being applied in one step
- C23C8/30—Carbo-nitriding
- C23C8/32—Carbo-nitriding of ferrous surfaces
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
The invention provides a carbonitriding heat treatment method and an alloy part prepared by the carbonitriding heat treatment method, and relates to the technical field of heat treatment processing, wherein the heat treatment method uses RX heat absorption type gas as carrier gas to load enriched gas and air so as to adjust the carbon potential of a heat treatment atmosphere; the RX endothermic gas comprises the following gases in percentage by volume: 20.5% of CO and H241％、N238.5 percent. The RX heat absorption type gas is used as reaction gas, so that the formation of non-martensite structures and oxides on the surface of the part in the heat treatment process can be effectively reduced, and the surface hardness, the wear resistance and the fatigue resistance of the part are improved; meanwhile, compared with the existing carbonitriding heat treatment method which takes methanol instillation cracking gas as carrier gas and adds enriching gas and balance air, the heat treatment method has better economical efficiency.
Description
Technical Field
The invention relates to the technical field of heat treatment processing, in particular to a carbonitriding heat treatment method and an alloy part prepared by the carbonitriding heat treatment method.
Background
During the carburizing heat treatment (carbonitriding), when the O in the carburizing furnace gas2、H2O、CO2When the content of the oxidizing gas is high or the surface of the part has a severe scale, an oxide is formed on the outermost surface during the carburizing heat treatment. Then, while oxygen diffuses along the grain boundaries, Cr, Si, and Mn in the grains diffuse into the oxygen in the grain boundaries, and an oxide is formed on the grain boundaries (generally, the intra-grain oxidation and the grain boundaries oxidationCollectively referred to as internal oxidation) while depleting the matrix in the vicinity of the oxides of carbon and alloying elements and reducing the hardenability in the vicinity of the layer, thereby forming a troostite-type structure having primary ferrite, primary troostite (connected together as a black band and not connected as a black net), and bainite in some steel types, all referred to as non-martensitic structures.
The generation of the non-martensite structure can reduce the surface hardness and the wear resistance of the part subjected to the carburizing heat treatment or the carbonitriding heat treatment, reduce the beneficial residual compressive stress on the surface of the part, even form the residual tensile stress on the surface, reduce the fatigue strength of the part and reduce the service life.
Therefore, it is necessary and urgent to develop a carburizing heat treatment process to reduce the formation of oxides on the surface of the part during the carburizing heat treatment and to improve the surface hardness, wear resistance and fatigue resistance of the part.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The first purpose of the invention is to provide a carbonitriding heat treatment method which can effectively reduce the formation of non-martensite structures and oxides on the surface of a part in the heat treatment process and improve the surface hardness, wear resistance and fatigue resistance of the part.
The second purpose of the invention is to provide an alloy part prepared by the carbonitriding heat treatment method.
The invention provides a carbonitriding heat treatment method, which uses RX heat absorption gas as carrier gas to load enriched gas and air to adjust the carbon potential of heat treatment atmosphere;
the RX endothermic gas comprises the following gases in percentage by volume: 20.5% of CO and H2 41％、N238.5％。
Further, the enriching gas comprises one of methane, propane, kerosene, acetone and propylene, and is preferably propane.
Further, the flow speed of the enriched gas in the heat treatment process is 2-5L/min;
the flow velocity of air in the heat treatment process is 2-5L/min;
the flow rate of RX heat absorption type gas in the heat treatment process is 10-15 m3H, preferably 13m3/h。
Further, the method comprises the following steps:
providing a part to be treated, placing the part to be treated in a heat treatment furnace, heating to 920-940 ℃ for carbonitriding to obtain a carbonitrided part;
the carbonitriding includes a stage a and a stage B performed in this order, wherein: the carbon potential of the heat treatment atmosphere in the stage A is 1.1-1.2%, and the treatment time is 245-255 min; the carbon potential of the heat treatment atmosphere in the stage B is 0.75%, and the treatment time is 225-235 min.
Further, the heat treatment method further comprises the steps of quenching and tempering.
Further, the quenching step comprises: quenching the carbonitrided part for 25-35 min at 830-850 ℃ under the condition that the carbon potential of the heat treatment atmosphere is 0.75% to obtain a quenched part;
preferably, the quenching medium is quenching oil at 50-70 ℃, and is preferably shangkishi brand 2080 type fast oil;
preferably, the time from the end of carbonitriding to the oil quenching of the carbonitrided part is 35-38 seconds.
Further, the tempering step is as follows: cleaning the quenched part, directly tempering, keeping the temperature at 160-180 ℃ for 175-185 min, and cooling to 20-25 ℃ to obtain the part.
Further, the method comprises the following steps:
(a) and carbonitriding: providing a part to be treated, placing the part to be treated in a heat treatment furnace, and sequentially carrying out stage A and stage B treatment to obtain a carbonitrided part;
wherein: the treatment temperature of the stage A is 920-940 ℃, the carbon potential of the reaction atmosphere is 1.1%, and the treatment time is 245-255 min;
the treatment temperature of the stage B is 920-940 ℃, the carbon potential of the reaction atmosphere is 0.75%, and the treatment time is 245-255 min;
(b) and quenching: quenching the part subjected to carbonitriding in the step (a) for 25-35 min at 830-850 ℃ under the condition that the carbon potential of the reaction atmosphere is 0.75% to obtain a quenched part;
(c) and tempering: cleaning the quenched part, then preserving heat at 160-180 ℃ for 175-185 min, and cooling to 20-25 ℃ to obtain a heat-treated part;
the carbon potential of the reaction atmosphere of the step (a) and the step (b) is adjusted by taking RX endothermic gas as carrier gas to carry enriching gas and air, wherein:
the flow rate of the enriched gas in the heat treatment process is 2-5L/min; the flow velocity of air in the heat treatment process is 2-5L/min; the flow rate of the RX endothermic gas in the heat treatment process is 10-15 m3/h, preferably 13m 3/h.
The alloy part provided by the invention is mainly prepared by the carbonitriding heat treatment method;
preferably, the alloy part is an automobile gearbox part.
Further, the grain boundary oxidation depth of the alloy part is 10-20 microns;
the surface hardness of the alloy part is the hardness at the position of 0.1mm of the conical surface: 698 to 705HV 1; hardness of the center of the conical surface: 36.0 HRC; taper-a 1 effective hardened layer: CHD550HV1 ═ 1.250 mm.
The metallographic structure of the infiltration layer of the alloy part is a surface martensite structure grade 3, and the residual austenite structure: grade 3, carbide grade 1, and standard 'carburization quenching tempering metallographic examination of steel parts GB/T25744-2010'.
Compared with the prior art, the invention has the beneficial effects that:
the carbonitriding heat treatment method provided by the invention is characterized in that RX endothermic gas is used as carrier gas to carry enriched gas and air so as to adjust the carbon potential of the heat treatment atmosphere; the RX endothermic gas contains nitrogen, hydrogen and carbon monoxide. The heat treatment method mixes fuel gas and natural gas with air according to a certain proportion and then introduces the gasThe generator is heated, and the RX heat absorption type gas is generated by absorbing heat under the action of the catalyst, and is used as the reaction gas, so that the formation of non-martensite structures and oxides on the surface of the part in the heat treatment process can be effectively reduced, and the surface hardness, the wear resistance and the fatigue resistance of the part are improved; meanwhile, compared with the existing carbonitriding heat treatment method for dripping methanol, the heat treatment method has better economical efficiency and 20m3the/L can be used for 7 1-ton devices.
The alloy part provided by the invention is mainly prepared by the carbonitriding heat treatment method, and has the advantages of high surface hardness, and strong wear resistance and fatigue resistance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a graph of grain boundary oxidation of a heat-treated part before process optimization in example 4 provided in Experimental example 1 of the present invention;
FIG. 2 is a graph of the interface oxidation of the part after the heat treatment process of example 4 provided in Experimental example 1 of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
According to an aspect of the present invention, a carbonitriding heat treatment method using an RX endothermic gas as a carrier gas to carry a enriching gas and air to adjust a carbon potential of a heat treatment atmosphere;
the RX endothermic gas contains nitrogen, hydrogen and carbon monoxide.
The carbonitriding heat treatment method provided by the invention is characterized in that RX endothermic gas is used as carrier gas to carry enriched gas and air so as to adjust the carbon potential of the heat treatment atmosphere; the RX endothermic gas contains nitrogen, hydrogen and carbon monoxide. The heat treatment method mixes the fuel gas and the natural gas with air according to a certain proportion, then introduces the mixture into the gas generator for heating, absorbs heat under the action of the catalyst to generate RX heat absorption type gas, and the RX heat absorption type gas is used as reaction gas, so that the formation of non-martensite structures and oxides on the surface of the part in the heat treatment process can be effectively reduced, and the surface hardness, the wear resistance and the fatigue resistance of the part are improved; meanwhile, compared with the existing carbonitriding heat treatment method for dripping methanol, the heat treatment method has better economical efficiency and 20m3the/L can be used for 7 1-ton devices.
The preparation method of the RX heat absorption type gas comprises the following steps that natural gas enters a mixer through a pressure reducing valve, a flowmeter and a pressure regulating valve to be mixed with air; air enters the mixer through the filter and the flowmeter, and the mixed gas of natural gas and air is pumped into the reaction tank; the pipeline is provided with a safety device, and the mixed gas is subjected to chemical reaction in the reaction tank under the action of the catalyst to generate endothermic atmosphere. At the same time, because the RX endothermic atmosphere also contains a small amount of CO2And H2O, and therefore the atmosphere of the RX endothermic generator, whose water gas reaction type can be accurately measured and controlled by the dew point method, contains nitrogen gas, hydrogen gas and carbon monoxide gas.
An exemplary preparation method of the RX endothermic gas used in the present invention is as follows:
CH4and air (21% O therein)2+79％N2) Mixing the components according to a proper proportion to generate a certain volume of RX heat absorption type atmosphere, wherein the gas comprises the following main components: 20.5% CO + 41% H2+38.5％N2；
The chemical reaction formula of methane and air is: CH (CH)4+2.38(0.21O2+0.79N2)->CO+2H2+1.88N2；
In a preferred embodiment of the present invention, the enriching gas comprises one of methane, propane, kerosene, acetone and propylene, preferably propane.
In a preferred embodiment, the enriching gas is preferably propane in order to ensure the gas exchange rate.
In a preferred embodiment of the invention, the flow rate of the enriching gas in the heat treatment process is 2-5L/min;
the flow velocity of air in the heat treatment process is 2-5L/min;
the flow rate of RX heat absorption type gas in the heat treatment process is 10-15 m3H, preferably 13m3/h。
In a preferred embodiment, the heat treatment process is preferably 13m3The volume of the furnace chamber is 3-5 times of the volume of the furnace chamber.
In a preferred embodiment of the invention, the method comprises the steps of:
providing a part to be treated, placing the part to be treated in a heat treatment furnace, heating to 920-940 ℃ for carbonitriding to obtain a carbonitrided part;
the carbonitriding includes a stage a and a stage B performed in this order, wherein: the carbon potential of the heat treatment atmosphere in the stage A is 1.1%, and the treatment time is 245-255 min; the carbon potential of the heat treatment atmosphere in the stage B is 0.75%, and the treatment time is 225-235 min.
In a preferred embodiment, the surface hardness, effective depth of hardened layer, retained austenite and carbide of the part are sufficiently ensured to satisfy the above-mentioned requirements.
In a preferred embodiment of the present invention, the heat treatment method further comprises the steps of quenching and tempering.
In a preferred embodiment of the present invention, the quenching step is: quenching the carbonitrided part for 25-35 min at 830-850 ℃ under the condition that the carbon potential of the heat treatment atmosphere is 0.75% to obtain a quenched part;
in a preferred embodiment, the quenching satisfies the requirements of surface hardness, core hardness and deformation control of the component.
Preferably, the quenching medium is quenching oil at the temperature of 50-70 ℃;
in the above preferred embodiment, the time from the end of carbonitriding to the time of quenching in oil of the carbonitrided part is 35 to 38 seconds.
In a preferred embodiment, the time from the end of carbonitriding to the time of quenching and oiling of the component after carbonitriding is 35 to 38 seconds, and the formation of a non-martensitic structure on the surface of the component due to temperature drop during the transfer process can be reduced compared to the conventional technique in which the transfer time is 45 to 50 seconds.
In a preferred embodiment of the present invention, the tempering step is: cleaning the quenched part, then preserving the heat at 160-180 ℃ for 175-185 min, and cooling to 20-25 ℃ to obtain the part.
In a preferred embodiment, the tempering temperature and the tempering time can fully eliminate the residual stress generated during quenching while ensuring the hardness of the part, prolong the service life of the part and improve the mechanical properties of the product.
In a preferred embodiment of the invention, the method comprises the steps of:
(a) and carbonitriding: providing a part to be treated, placing the part to be treated in a heat treatment furnace, and sequentially carrying out stage A and stage B treatment to obtain a carbonitrided part;
wherein: the treatment temperature of the stage A is 920-940 ℃, the carbon potential of the reaction atmosphere is 1.1%, and the treatment time is 245-255 min;
the treatment temperature of the stage B is 920-940 ℃, the carbon potential of the reaction atmosphere is 0.75%, and the treatment time is 245-255 min;
(b) and quenching: quenching the part subjected to carbonitriding in the step (a) for 25-35 min at 830-850 ℃ under the condition that the carbon potential of the reaction atmosphere is 0.75% to obtain a quenched part;
(c) and tempering: cleaning the quenched part, then preserving heat at 160-180 ℃ for 175-185 min, and cooling to 20-25 ℃ to obtain a heat-treated part;
the carbon potential of the reaction atmosphere of the step (a) and the step (b) is adjusted by taking RX endothermic gas as carrier gas to carry enriching gas and air, wherein:
the flow rate of the enriched gas in the heat treatment process is 2-5L/min; the flow velocity of air in the heat treatment process is 2-5L/min; the flow speed of the RX endothermic gas in the heat treatment process is 10-15 m3/h, preferably 13m 3/h.
Preferably, the heat treatment method further comprises a step of cleaning the part to be treated before step (a), specifically: the cleaning process adopts spray cleaning, the cleaning adopts a pure environment-friendly hydrocarbon organic solvent, the solvent has excellent solubility to metal processing and various quenching oils, and the solvent has no toxicity which is different from the toxic system containing Cl and F. The vacuum hydrocarbon solvent cleaning machine consists of a cleaning device and a regeneration device, the regeneration device can continuously distill and recover the dirty liquid after cleaning, and the cleaning device is ensured to always use a cleaning solvent.
According to one aspect of the present invention, an alloy part is mainly prepared by the carbonitriding heat treatment method described above;
the alloy part provided by the invention is mainly prepared by the carbonitriding heat treatment method, and has the advantages of high surface hardness, and strong wear resistance and fatigue resistance.
Preferably, the alloy part is an automobile gearbox part.
In a preferred embodiment of the invention, the grain boundary oxidation depth of the alloy part is 10-20 microns;
the surface hardness of the alloy part is the hardness at the position of 0.1mm of the conical surface: 698. 700, 702, 705HV 1; hardness of the center of the conical surface: 36.0 HRC; taper-a 1 effective hardened layer: CHD550HV1 ═ 1.250 mm;
the metallographic structure of the infiltration layer of the alloy part is a surface martensite structure grade 3, and the residual austenite structure: grade 3, carbide grade 1, and standard 'carburization quenching tempering metallographic examination of steel parts GB/T25744-2010'.
The technical solution of the present invention will be further described with reference to examples and comparative examples.
Example 1
A method of producing an RX endothermic gas, comprising the steps of:
the fuel gas and natural gas are mixed with air according to a certain proportion and then are fed into a gas generator for heating, and gas is generated by absorbing heat under the action of a catalyst. Since the main component of natural gas is methane (CH4), the chemical reaction formula of methane and air is: CH (CH)4+2.38(0.21O2+0.79N2)->CO+2H2+1.88N2；
The volume ratio of nitrogen, hydrogen and carbon monoxide in the RX endothermic gas prepared by the method is 20.5% CO + 41% H2+38.5％N2And contains a small amount of CO2And H2O。
Example 2
A carbonitriding heat treatment method, the method comprising the steps of:
(a) and carbonitriding: providing a part to be treated, carrying out vacuum cleaning on the part to be treated by a VCH (hydrocarbon hydrogen chloride) solvent, putting the cleaned part to be treated in a heat treatment furnace, and sequentially carrying out stage A and stage B treatment to obtain a carbonitrided part;
wherein: the treatment temperature of the stage A is 920 ℃, the carbon potential of the reaction atmosphere is 1.1 percent, and the treatment time is 245 min;
the treatment temperature of the stage B is 920 ℃, the carbon potential of the reaction atmosphere is 0.75 percent, and the treatment time is 255 min;
(b) and quenching: quenching the part subjected to carbonitriding in the step (a) for 25min at 830 ℃ under the condition that the carbon potential of the reaction atmosphere is 0.75 to obtain a quenched part;
(c) and tempering: keeping the temperature of the quenched part at 180 ℃ for 185min, and cooling to 20 ℃ to obtain a heat-treated part;
the carbon potential of the reaction atmosphere of the step (a) and the step (b) is adjusted by taking RX endothermic gas as carrier gas to carry propane and air, wherein:
the flow rate of propane in the heat treatment process is 5L/min at the early stage, and the flow rate is 2L/min after the carbon potential is adjusted; the flow velocity of air in the heat treatment process is 2-5L/min; the flow velocity of RX endothermic gas in the heat treatment process is 13m3/h。
Example 3
A carbonitriding heat treatment method, the method comprising the steps of:
(a) and carbonitriding: providing a part to be treated, cleaning the part by using a VCM water agent, placing the cleaned part to be treated in a heat treatment furnace, and sequentially carrying out stage A and stage B treatment to obtain a part subjected to carbonitriding;
wherein: the treatment temperature of the stage A is 940 ℃, the carbon potential of the reaction atmosphere is 1.1 percent, and the treatment time is 255 min;
the treatment temperature of the stage B is 940 ℃, the carbon potential of the reaction atmosphere is 0.75 percent, and the treatment time is 245 min;
(b) and quenching: quenching the part subjected to carbonitriding in the step (a) for 35min at 850 ℃ under the condition that the carbon potential of the reaction atmosphere is 0.75 to obtain a quenched part;
(c) and tempering: cleaning the quenched part, keeping the temperature at 160 ℃ for 175min, and cooling to 20 ℃ to obtain a heat-treated part;
the carbon potential of the reaction atmosphere of the step (a) and the step (b) is adjusted by taking nitrogen methanol as a carrier gas to carry propane and air, wherein:
the flow rate of propane in the heat treatment process is 5L/min at the early stage, and the flow rate is 2L/min after the carbon potential is adjusted; the flow velocity of air in the heat treatment process is 2-5L/min; the flow velocity of RX endothermic gas in the heat treatment process is 13m3/h。
Example 4
A carbonitriding heat treatment method, the method comprising the steps of:
(a) and carbonitriding: providing a part to be treated, carrying out vacuum cleaning on the part to be treated by a VCH (hydrocarbon hydrogen chloride) solvent, putting the cleaned part to be treated in a heat treatment furnace, and sequentially carrying out stage A and stage B treatment to obtain a carbonitrided part;
wherein: the treatment temperature of the stage A is 930 ℃, the carbon potential of the reaction atmosphere is 1.1 percent, and the treatment time is 250 min;
the treatment temperature of the stage B is 930 ℃, the carbon potential of the reaction atmosphere is 0.75 percent, and the treatment time is 250 min;
(b) and quenching: quenching the part subjected to carbonitriding in the step (a) for 30min at 840 ℃ under the condition that the carbon potential of the reaction atmosphere is 0.75% to obtain a quenched part;
(c) and tempering: cleaning the quenched part, keeping the temperature at 170 ℃ for 180min, and cooling to 23 ℃ to obtain a heat-treated part;
the carbon potential of the reaction atmosphere of the step (a) and the step (b) is adjusted by taking RX endothermic gas as carrier gas to carry propane and air, wherein:
the flow rate of propane in the heat treatment process is 5L/min at the early stage, and the flow rate is 2L/min after the carbon potential is adjusted; the flow velocity of air in the heat treatment process is 2-5L/min; the flow velocity of RX endothermic gas in the heat treatment process is 13m3/h。
Comparative example 1 existing conventional carbonitriding heat treatment process:
a carbonitriding heat treatment method, the method comprising the steps of:
(a) and carbonitriding: providing a part to be treated, cleaning the part by using a VCM water agent, placing the cleaned part to be treated in a heat treatment furnace, and sequentially carrying out stage A, stage B and stage C treatment to obtain a part subjected to carbonitriding;
wherein: the treatment temperature of the stage A is 940 ℃, the carbon potential of the reaction atmosphere is 1.2 percent, and the treatment time is 220 min;
the treatment temperature of the stage B is 940 ℃, the carbon potential of the reaction atmosphere is 1.05 percent, and the treatment time is 130 min;
the treatment temperature of the stage C is 930 ℃, the carbon potential of the reaction atmosphere is 0.85 percent, and the treatment time is 190 min;
(b) and quenching: quenching the part subjected to carbonitriding in the step (a) for 1min at 850 ℃ under the condition that the carbon potential of the reaction atmosphere is 0.65% to obtain a quenched part;
(c) and tempering: cleaning the quenched part, keeping the temperature at 190 ℃ for 120min, and cooling to 23 ℃ to obtain a heat-treated part;
adding a nitrogen source in the reaction atmosphere of the step (a) and the step (b) by dripping methanol, wherein the flow rate of propane in the heat treatment process is 5L/min at the early stage, and the flow rate is 2L/min after the carbon potential is adjusted; the flow velocity of air in the heat treatment process is 2-5L/min; the dropping flow rate of the methanol in the heat treatment process is 2500 ml/min.
Experimental example 1
To show that the carbonitriding heat treatment method of the present application has a good heat treatment effect, taking the part after heat treatment in example 4 as an example, taking 4% nitric acid alcohol as an etchant, and observing the oxidation depth of the grain boundary under a 500X metallographic microscope, specific results are shown in fig. 1 and fig. 2:
FIG. 1 is a graph of grain boundary oxidation of a heat treated part before process optimization;
FIG. 2 is a graph of interfacial oxidation of a part after a heat treatment process;
as can be seen from fig. 1 and 2, the oxidation depth of the grain boundary after the heat treatment of the present invention is only 19.39 micrometers, while the interface oxidation depth of the heat-treated part before the process optimization is about 41.98 micrometers. Therefore, the carbonitriding heat treatment method can effectively reduce the formation of non-martensite structures and oxides on the surface of the part in the heat treatment process, and improve the surface hardness, wear resistance and fatigue resistance of the part.
Experimental example 2
In order to show that the alloy part prepared by the carbonitriding heat treatment method can effectively reduce the formation of non-martensite structures and oxides on the surface of the part in the heat treatment process, and improve the surface hardness, wear resistance and fatigue resistance of the part, the following detection experiments are carried out on the alloy part prepared in the embodiment 1-2:
example 1: the surface hardness of the alloy part is the hardness at the position of 0.1mm of the conical surface: 689. 680, 701, 668HV 1; hardness of the center of the conical surface: 38.0 HRC; taper-a 1 effective hardened layer: CHD550HV1 is 1.320mm, grain boundary oxidation depth is 40 microns, cone run-out is 0.2, flatness is less than 0.024, roundness is 0.0342, and the run-out exceeds the customer specification by 0.15: surface martensite structure grade 5, retained austenite structure: grade 5, carbide grade 1, and standard' carburization quenching tempering metallographic examination of steel parts GB/T25744-.
Example 2: the surface hardness of the alloy part is the hardness at the position of 0.1mm of the conical surface: 698. 700, 702, 705HV 1; hardness of the center of the conical surface: 36.0 HRC; taper-a 1 effective hardened layer: the CHD550HV1 is 1.250mm, the grain boundary oxidation depth is 10-20 microns, the cone run-out is 0.054, the flatness is less than 0.02, and the roundness is 0.024, so that the requirements of customers are met. The metallographic structure of the infiltration layer of the alloy part is a surface martensite structure grade 3, and the residual austenite structure: grade 3, carbide grade 1, and standard' carburization quenching tempering metallographic examination of steel parts GB/T25744-.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A carbonitriding heat treatment method is characterized in that RX endothermic gas is used as carrier gas to carry enriched gas and balance air so as to adjust the carbon potential of the heat treatment atmosphere;
the RX endothermic gas comprises the following gases in percentage by volume: 20.5% of CO and H2 41％、N2 38.5％。
2. The carbonitriding heat treatment process according to claim 1, wherein the enriching gas comprises one of methane, propane, kerosene, acetone, and propylene, preferably propane.
3. The carbonitriding heat treatment method according to claim 1, wherein a flow rate of the enriching gas during the heat treatment is 2 to 5L/min;
the flow velocity of balance air in the heat treatment process is 2-5L/min;
the flow rate of RX heat absorption gas in the heat treatment process is 10-15 m3H, preferably 13m3/h。
4. The carbonitriding heat treatment process according to claim 1, characterized in that the process comprises the steps of:
providing a part to be treated, placing the part to be treated in a heat treatment furnace, heating to 920-940 ℃ for carbonitriding to obtain a carbonitrided part;
the carbonitriding includes a stage a and a stage B performed in this order, wherein: the carbon potential of the heat treatment atmosphere in the stage A is 1.1-1.2%, and the treatment time is 245-255 min; the carbon potential of the heat treatment atmosphere in the stage B is 0.75%, and the treatment time is 225-235 min.
5. The carbonitriding heat treatment process according to claim 1, characterized in that the heat treatment process further comprises the steps of quenching and tempering.
6. The carbonitriding heat treatment method according to claim 5, wherein the quenching step is: quenching the carbonitrided part for 25-35 min at 830-850 ℃ under the condition that the carbon potential of the heat treatment atmosphere is 0.75% to obtain a quenched part;
preferably, the quenching medium is quenching oil at 50-70 ℃;
preferably, the time from the end of carbonitriding to the oil quenching of the carbonitrided part is 35-38 seconds.
7. The carbonitriding heat treatment method according to claim 5, wherein the tempering step is: and cleaning the quenched part, directly tempering, preserving heat at 160-180 ℃ for 175-185 min, and cooling to 20-25 ℃ to obtain the part.
8. The carbonitriding heat treatment process according to claim 1, characterized in that the process comprises the steps of:
(a) and carbonitriding: providing a part to be treated, cleaning the part to be treated, placing the part to be treated in a heat treatment furnace, and sequentially carrying out stage A and stage B treatment to obtain a carbonitrided part;
wherein: the treatment temperature of the stage A is 920-940 ℃, the carbon potential of the reaction atmosphere is 1.1%, and the treatment time is 245-255 min;
the treatment temperature of the stage B is 920-940 ℃, the carbon potential of the reaction atmosphere is 0.75%, and the treatment time is 245-255 min;
(b) and quenching: quenching the part subjected to carbonitriding in the step (a) for 25-35 min at 830-850 ℃ under the condition that the carbon potential of the reaction atmosphere is 0.75% to obtain a quenched part;
(c) and tempering: cleaning the quenched part, then preserving heat at 160-180 ℃ for 175-185 min, and cooling to 20-25 ℃ to obtain a heat-treated part;
the carbon potential of the reaction atmosphere of the step (a) and the step (b) is adjusted by taking RX endothermic gas as carrier gas to carry enriching gas and air, wherein:
the flow rate of the enriched gas in the heat treatment process is 2-5L/min; the flow velocity of air in the heat treatment process is 2-5L/min; the flow velocity of RX heat absorption type gas in the heat treatment process is 10-15 m3H, preferably 13m3/h。
9. An alloy part, characterized in that the alloy part is mainly prepared by the carbonitriding heat treatment method according to any one of claims 1 to 8;
preferably, the alloy part is an automobile gearbox part.
10. The alloy part according to claim 9, wherein the alloy part has a grain boundary oxidation depth of 10 to 20 μm;
the surface hardness of the alloy part is the hardness at the position of 0.1mm of the conical surface: 698 to 705HV 1; hardness of the center of the conical surface: 36.0 HRC; taper-a 1 effective hardened layer: CHD550HV1 ═ 1.250 mm.
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| CN116536618A (en) * | 2023-05-23 | 2023-08-04 | 江苏丰东热技术有限公司 | Novel carbonitriding process for bearing product |
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