WO2003104516A1 - Procede de cementation gazeuse - Google Patents

Procede de cementation gazeuse Download PDF

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Publication number
WO2003104516A1
WO2003104516A1 PCT/JP2003/005422 JP0305422W WO03104516A1 WO 2003104516 A1 WO2003104516 A1 WO 2003104516A1 JP 0305422 W JP0305422 W JP 0305422W WO 03104516 A1 WO03104516 A1 WO 03104516A1
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WIPO (PCT)
Prior art keywords
carburizing
gas
temperature
treated
partial pressure
Prior art date
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PCT/JP2003/005422
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English (en)
Japanese (ja)
Inventor
暁華 立里
Original Assignee
光洋サーモシステム株式会社
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Publication date
Priority claimed from PCT/JP2002/005767 external-priority patent/WO2003104515A1/fr
Application filed by 光洋サーモシステム株式会社 filed Critical 光洋サーモシステム株式会社
Priority to AU2003235955A priority Critical patent/AU2003235955A1/en
Priority to EP03723223A priority patent/EP1598440B1/fr
Priority to JP2004511572A priority patent/JP3696614B2/ja
Priority to US10/487,398 priority patent/US7416614B2/en
Priority to KR1020047002043A priority patent/KR100592757B1/ko
Priority to DE60333039T priority patent/DE60333039D1/de
Publication of WO2003104516A1 publication Critical patent/WO2003104516A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/20—Carburising
    • C23C8/22—Carburising of ferrous surfaces

Definitions

  • the present invention relates to a method for gas carburizing steel parts used, for example, in the automotive and mechanical industries. Background art
  • the carburizing time can be shortened by increasing the carburizing temperature.
  • the conventional carburizing temperature is the eutectic point temperature at which the liquid phase transforms to iron and cementite (in the equilibrium diagram of iron and carbon shown in Fig. 1, the C point temperature is 114). Less than 7, typically less than 150 ° C
  • the carburizing process is performed until the carbon concentration in the surface layer of the object to be treated becomes higher than the final target value, and then the carbon concentration is lower than the carburizing atmosphere.
  • the carbon concentration in the surface layer was reduced to the final target value (see Japanese Patent Publication No. 6-458886).
  • the carburizing temperature is limited to less than the eutectic point temperature, the diffusion rate of carbon atoms in the object to be treated is restricted, so that the carburizing time cannot be significantly reduced. In other words, there is a problem that productivity is reduced because the diffusion treatment takes a long time.
  • An object of the present invention is to provide a gas carburizing method that can solve such a conventional problem. Disclosure of the invention
  • the carburization temperature is not higher than the peritectic point temperature at which ⁇ iron and a liquid phase are transformed to iron and the temperature is not less than the eutectic point temperature at which the liquid phase is transformed to iron and cementite.
  • the carburizing time can be reduced by heating the object to be treated to as high a temperature as possible and performing gas carburizing in an austenitized state.
  • the concentration of carburizing gas in the carburizing atmosphere it is possible to prevent the hardened layer on the object to be processed from becoming shallow, and to obtain a hardened layer having a sufficient thickness in a short time.
  • the object to be treated turns to austenite when heated to a temperature above the GS and ES lines in the equilibrium diagram of iron and carbon shown in Fig. 1. If the carbon concentration in the surface layer of the object exceeds the J-line, melting starts in that surface layer.
  • the present inventor has determined that, for carburizing conditions such as carburizing temperature and carburizing time, there is an upper limit of the carburizing gas partial pressure at which the surface layer of the object to be treated does not melt, and the upper limit is that the carburizing temperature is higher. And that the shorter the carburizing time, the higher.
  • the carburizing temperature range in the gas carburizing method according to the present invention is lower than the peritectic point temperature (1494 ° C) and higher than the eutectic point temperature (1147 ° C), the carburizing time can be greatly increased. Can be shortened. Moreover, by setting the partial pressure of the carburizing gas at or below the previously determined upper limit, carburization at a high temperature can be performed without melting the surface layer of the object to be treated. As a result, energy consumption can be significantly reduced and energy can be saved. In addition, the gas carburizing step can be performed in succession with other steps, for example, a machining step or a different heat treatment step.
  • the limit carburizing conditions include the upper limit of the carburizing temperature and the upper limit of the carburizing time at which the surface layer of the sample is austenitized without melting, and the upper limit of the carburizing gas partial pressure.
  • the relationship between the upper limit of the carburizing temperature and the upper limit of the carburizing time is determined in advance, and the carburizing gas is set so that the carburizing condition of the object to be treated does not violate the limit carburizing condition that satisfies the obtained relationship. It is preferable to set the partial pressure, carburizing temperature and carburizing time.
  • the upper limit of carburizing gas partial pressure, the upper limit of carburizing temperature and the upper limit of carburizing time as the limiting carburizing conditions are related to each other, and two of carburizing gas partial pressure, carburizing temperature and carburizing time are fixed. By doing so, the remaining upper limit can be obtained. This makes it easy to set the carburizing conditions as fast as possible within a range where the surface layer of the object to be treated does not melt.
  • Another feature of the gas carburizing method of the present invention is that, when performing gas carburizing of a steel object to be treated, the carburizing temperature is changed to the peritectic point temperature at which ⁇ iron and the liquid phase are transformed into iron.
  • the eutectic point temperature is below J 1 419 1) at the J point temperature, and the liquid phase transforms into iron and cementite (in the case of Fig. 1, the temperature at the C point is 1 147 ° C)
  • the target value of the surface carbon concentration of the object to be treated is set to a value that does not cause the surface of the object to be treated to melt at the set carburizing temperature, and the partial pressure of the carburizing gas in the carburizing atmosphere is set in advance.
  • the point is that the surface carbon concentration of the object to be treated is set to a value that can reach the set target value by gas carburizing for the set time.
  • the carburizing temperature is set to be lower than the peritectic point temperature and higher than the eutectic point temperature, and the target value of the surface carbon concentration of the steel object is set. If the carburizing gas partial pressure in the carburizing atmosphere is set to an appropriate value, the surface carbon concentration of the object to be treated will reach the set target value due to gas carburizing, and the carburizing depth will be sufficient. It is based on the discovery that it can be obtained. Carburization at high temperature allows carbon atoms to move faster during carburization than in the past, making it possible to reach the oxidized layer depth in a short time, which previously required several hours to reach. And the surface carbon concentration does not become excessively high.
  • the carburizing time can be significantly reduced by increasing the carburizing temperature.
  • the carbon concentration in the surface layer of the processing object does not exceed the set target value, the carbon diffusion processing step is not required. Thereby, productivity can be improved.
  • the gas carburizing process can be performed continuously with other heat treatment processes. Therefore, It is preferable to cool the object to be treated without performing the diffusion treatment after performing the gas carburizing of the above. After the cooling, the object to be processed is preferably reheated. This reheating is performed by, for example, high frequency heating. It is preferable to perform a filling treatment of the reheated processing object.
  • the cooling for the quenching process is performed by oil cooling or gas cooling, for example.
  • the carburizing temperature is 120 Ot: or more from the viewpoint of shortening the carburizing time.
  • ⁇ 5 peritectic transformation from iron and liquid phase to iron At a carburizing temperature below the eutectic point, below the eutectic point where the liquid phase transforms to iron and cementite from the liquid phase, the surface layer of the sample of steel to be treated in the carburizing atmosphere is not austenite
  • the limit carburizing conditions should include the upper limit of carburizing gas partial pressure in the carburizing atmosphere where the surface layer of the sample is austenitized without melting.
  • the object to be treated becomes austenite when heated to a temperature above the GS and ES lines in the iron-carbon equilibrium diagram shown in Fig. 1. If the carbon concentration in the surface layer of the object exceeds the JE line, melting starts in that surface layer.
  • carburizing conditions such as carburizing temperature and carburizing time
  • the limit carburizing conditions including the upper limit of the carburizing gas partial pressure, setting of the carburizing gas partial pressure and carburizing time becomes easy.
  • the total pressure of the carburizing atmosphere may be normal pressure, may be reduced from normal pressure, or may be pressurized.
  • the entire carburizing atmosphere may be a carburizing gas, or a mixed gas of a carburizing gas and a diluting gas may be a carburizing atmosphere.
  • a diluent gas it is preferable to dilute with an inert gas such as nitrogen gas or argon gas.
  • the steel type of the object to be treated to which the gas carburizing method of the present invention is applied is not particularly limited, as long as the steel is austenitized at a temperature lower than the peritectic point temperature and higher than the eutectic point temperature. It can be applied not only to steel but also to alloy steel.
  • the object to be treated and the sample are preferably heated by means capable of heating the surface layer at a high speed.
  • induction heating or laser heating preferable.
  • the heating efficiency of the carburizing target can be improved.
  • the carburizing process is simple, quality control becomes easy. That is, since there are few factors that affect the quality, it is easy to find the cause even if a quality problem such as spots, distortion, or cracks occurs in the object to be treated.
  • the wall covering the carburizing treatment space can be made a cold wall, and the exhaust gas combustion device is not required, so the working environment is not impaired, initial investment can be reduced, small-lot production of single items can be handled, and production lines can be used. Easy to assemble, for example, one-line inline processing is also possible. Since a conventional carburizing furnace equipped with heat insulating walls is not required, heating and seasoning of the furnace are not required, and running costs can be reduced.
  • the gas carburizing it is preferable to carry out the gas carburizing while flowing a carburizing atmosphere containing a carburizing gas at a constant partial pressure.
  • the carburizing gas partial pressure can be kept constant and the quality of the object to be treated can be made uniform.
  • productivity can be greatly improved.
  • Figure 1 is an equilibrium diagram of iron and carbon
  • FIG. 2 is a diagram showing a state in which a sample to be treated is heated by a gas carburizing apparatus according to an embodiment of the present invention.
  • Figure 3 shows an example of the relationship of the upper limit of carburizing gas partial pressure to different carburizing temperatures and carburizing times.
  • FIG. 4 is a diagram showing a state in which an object to be treated is heated by the gas carburizing apparatus according to the embodiment of the present invention.
  • Figure 5 shows the relationship between the carburizing time, the carburizing gas partial pressure, and the surface carbon concentration until the surface of the object starts melting at a carburizing temperature of 1573 K.
  • Figure 6 shows the relationship between carburizing time, carburizing gas partial pressure, and surface carbon concentration until the surface of the object to be treated starts melting at a carburizing temperature of 1623 K.
  • FIG. 7 shows that the carburizing was performed at a carburizing temperature of 125 ° C. and a carburizing time of 1 minute in the example of the present invention.
  • FIG. 8 is a diagram showing the relationship between the distance from the surface of the object to be treated carburized at a carburizing temperature of 1300 ° (the carburizing time of 1 minute and the hardness in the example of the present invention and the hardness.
  • FIG. 9 is a diagram showing the relationship between the distance from the surface of the object to be treated carburized at a carburizing temperature of 125 ° C. and a carburizing time of 10 minutes and the hardness in the example of the present invention.
  • FIG. 10 is a diagram showing the relationship between the distance from the surface of the object to be carburized at a carburizing temperature of 130 ° C. and a carburizing time of 10 minutes and the hardness in the embodiment of the present invention.
  • Fig. 11 shows the metal structure of the surface layer of the gas carburized object before quenching.
  • Fig. 12 shows the metal structure after quenching in the surface layer of the gas carburized object.
  • FIG. 13 is a diagram showing the relationship between the distance from the surface of the object to be treated and the carbon concentration obtained according to the embodiment of the present invention.
  • FIG. 14 is a diagram showing an example of the relationship among the carburizing time, the diffusion time, and the carbon concentration in the object to be treated by the conventional carburizing method.
  • the gas carburizing apparatus includes a vacuum vessel 1, a heating device 2, a vacuum pump 3 for reducing the pressure in the vacuum vessel 1, and a carburizing atmosphere in the vacuum vessel 1.
  • the heating device 2 performs induction heating in the vacuum vessel 1 by a coil 2 a connected to a power supply 7.
  • the output from the power supply 7 to the coil 2a is variable.
  • a thermocouple 6 is welded to the surface layer of the sample 5 ′ set in the heating device 2 as a temperature detection sensor in order to perform gas carburization of the sample 5 ′ of the steel processing object.
  • the air in the vacuum vessel 1 is evacuated by the vacuum pump 3 to reduce the pressure in the vacuum vessel 1. At this point, it is preferable to reduce the internal pressure of the vacuum vessel 1 to about 27 Pa or less.
  • the temperature detecting means is not limited to a thermocouple.
  • a carburizing atmosphere gas is introduced into the vacuum vessel 1 from the gas source 4. Thereby, the inside of the vacuum vessel 1 is filled with the carburizing atmosphere, and the total pressure of the carburizing atmosphere is increased.
  • the pressure of the carburizing atmosphere in the vacuum vessel 1 is increased to about 80 kPa.
  • the carburizing atmosphere is composed of a carburizing gas and a diluting gas.
  • the type of carburizing gas and dilution gas is not particularly limited.
  • the carburizing gas is methane gas
  • the diluting gas is nitrogen gas.
  • Non-oxidative carburization can be realized by using hydrocarbon gas as the carburizing gas.
  • the carburizing gas is not limited to a hydrocarbon-based gas.
  • the carburizing atmosphere may consist only of carburizing gas. In order to keep the total pressure of the carburizing atmosphere in the vacuum vessel 1 constant, a carburizing atmosphere gas is supplied from the gas source 4 into the vacuum vessel 1 at a constant flow rate, and the carburizing atmosphere gas is supplied at a constant flow rate by the vacuum pump 3. Exhaust.
  • the carburizing atmosphere gas flows at a constant flow rate of, for example, 0.5 L / min in the vacuum vessel 1, and the total pressure of the carburizing atmosphere is maintained at, for example, about 80 kPa. That is, the carburizing atmosphere containing the carburizing gas at a constant partial pressure flows in the vacuum vessel 1.
  • the partial pressure of the carburizing gas is a value obtained by multiplying the total pressure of the carburizing atmosphere in the vacuum vessel 1 by the molar fraction or volume% of the carburizing gas. Therefore, the set value of the carburizing gas partial pressure can be adjusted by changing the total pressure of the carburizing atmosphere in the vacuum vessel 1 or changing the flow ratio of the carburizing gas and the dilution gas.
  • the heating device 2 heats the sample 5 ′ to the set carburizing temperature.
  • the carburization temperature is set to be lower than the peritectic point temperature at which ⁇ iron and liquid phase transform to r-iron and higher than the eutectic point temperature at which liquid phase transforms to iron and cementite.
  • the set value of the carburizing temperature can be adjusted by changing the output to the coil 2a of the heating device 2. Under the set carburizing gas partial pressure and the set carburizing temperature, whether the surface layer of sample 5 'melts when gas carburizing is performed by holding sample 5' for the set carburizing time Check if.
  • set value of carburizing gas partial pressure Carburize sample 5 'with increasing pressure. If the surface layer of sample 5 'is molten, reduce the set value of the carburizing gas partial pressure to perform carburization of sample 5'.
  • the upper limit value of the partial pressure of the carburizing gas is determined in advance as the limit carburizing condition at which the surface layer of sample 5 'is austenitized without melting.
  • the present invention is not limited to this, and may be appropriately modified without departing from the spirit of the present invention. May be used. That is, the upper limit of the carburizing time may be obtained by keeping the carburizing gas partial pressure and the carburizing temperature constant, or the upper limit of the carburizing temperature may be obtained by keeping the carburizing gas partial pressure and the carburizing time constant.
  • FIG. 3 shows an example of the relationship between the upper limit of the carburizing gas partial pressure, the upper limit of the carburizing temperature, and the upper limit of the carburizing time, which was obtained in advance as described above. Although the ordinate in FIG.
  • the carburizing gas partial pressure is equal to the total pressure of the carburizing atmosphere, and the methane flow can be used to represent the carburizing gas partial pressure.
  • the upper limit of the partial pressure of the carburizing gas in the carburizing atmosphere decreases as the carburizing temperature increases, and increases as the carburizing time decreases.
  • the relationship shown in FIG. 3 is merely an example, and the relationship is, for example, the arrangement of the components of the heating device 2, the material and arrangement of the sample 5 'in the heating device 2, the type of the heating device 2, the type and the flow rate of the carburizing gas. Different if they are different. Thereafter, using the above-described gas carburizing apparatus, gas carburizing of the steel workpiece 5 is performed under the carburizing conditions set so as not to go against the limit carburizing conditions that satisfy the relation obtained in advance. The carburizing of the object 5 can be performed in the same manner as the carburizing of the sample 5 '. 5422 1 91
  • the object 5 to be treated is set in the heating device 2, the air in the vacuum vessel 1 is evacuated by the vacuum pump 3, and the gas for the carburizing atmosphere is introduced into the vacuum vessel 1 from the gas source 4.
  • the pressure of the carburizing atmosphere is increased to the set pressure, and the gas for the carburizing atmosphere is supplied into the vacuum vessel 1 from the gas source 4 at a constant flow rate, and the gas for the carburizing atmosphere is exhausted at a constant flow rate by the vacuum pump 3.
  • the partial pressure of the carburizing gas in the carburizing atmosphere in the vacuum vessel 1 is set to be equal to or less than the upper limit previously determined as the limit carburizing condition.
  • the object to be treated 5 is heated by the heating device 2 to the carburizing temperature.
  • the carburizing temperature is set at a temperature below the peritectic point temperature and above the eutectic point temperature.
  • the carburizing temperature at the time of heating the sample 5 ′ can be reproduced by controlling the heating device 2 in the same manner as when heating the sample 5 ′. No need to weld to 5.
  • gas carburizing is performed by holding the object 5 to be processed for the set carburizing time.
  • the carburization temperature is lower than the peritectic point temperature at which d iron and liquid phase transform to T iron, and the liquid phase transforms to r iron and cementite.
  • the target value of the surface carbon concentration of the processing object 5 is set to a value that does not cause the surface of the processing object 5 to melt at the set carburizing temperature.
  • the partial pressure of the carburizing gas in the carburizing atmosphere is set to a value at which the surface carbon concentration of the object to be treated can reach the set target value by the gas carburizing for a preset time.
  • the set value of the carburizing gas partial pressure with respect to the carburizing time may be obtained in advance by an experiment.
  • the setting of the carburizing time and the partial pressure of the carburizing gas can be made by obtaining the above upper limits in advance. It will be easier.
  • Fig. 5 shows the relationship between the carburizing time, the carburizing gas partial pressure, and the surface carbon concentration until the surface of the object 5 starts melting at K.
  • the carburizing time is 1 minute. If the methane concentration in the carbon atmosphere is 10 o It can be seen that the methane concentration in the carbon atmosphere should be set to less than 3 V o 1% if the carburizing time is less than 1% and the carburizing time is 10 minutes.
  • the carburizing temperature is 1623 K
  • the surface of the object 5 starts melting when the carbon concentration is about 0.9% by weight. Therefore, from the relationship shown in FIG.
  • the relationship between the carburizing time, the carburizing gas partial pressure and the surface carbon concentration until the surface of the object 5 starts melting at 3 K is shown in FIG.
  • the carburizing time is 1 minute
  • the methane concentration in the carbon atmosphere should be set to less than 1.8 V ⁇ 1% and the carburization time should be set to less than 0.8 ⁇ 1% if the carburization time is 10 minutes.
  • gas carburizing is performed by holding the object 5 to be treated for the set carburizing time. After the set carburizing time has elapsed, the carburizing is stopped by stopping the supply of the carburizing gas or by canceling the heating by the heating device 2.
  • the carburizing temperature range is lower than the peritectic point temperature and higher than the eutectic point temperature, so that the carburizing time can be greatly reduced.
  • the partial pressure of the carburizing gas to be equal to or less than the upper limit obtained in advance, carburization at a high temperature can be performed without melting the surface layer of the object 5 to be treated.
  • a 5 mm 2 sec, 1 3 0 0 Sometimes 1 0-fold or more 4 3 X 10- s mm 2 / sec.
  • the moving speed of carbon atoms is more than 10 times faster at 1300 ° C than at 100 ° C. Therefore, the time required to obtain a desired carburizing depth can be greatly reduced, and a normal carburizing depth can be obtained with a carburizing time of about 1 to 10 minutes.
  • the carbon diffusion processing step becomes unnecessary.
  • the carburizing time can be significantly reduced and productivity can be improved.
  • the gas carburizing process can be performed continuously with other heat treatment processes. Setting the carburizing temperature above 1200 ° C shortens the carburizing time. The temperature may be set to 130 ° C. or more.
  • gas carburizing is performed while flowing a carburizing atmosphere containing a carburizing gas at a constant partial pressure in the vacuum vessel 1, the carburizing gas partial pressure can be kept constant and the quality of the object 5 to be treated can be made uniform! ? ! Further, in the carburizing treatment performed in the present invention, no soot was generated at all, and in this respect, a very favorable result was obtained as compared with the conventional vacuum carburizing.
  • the object 5 After performing the gas carburizing, the object 5 is cooled without performing the diffusion process.
  • the cooling method is not particularly limited, and may be natural cooling or various forced cooling. Further, it is preferable to quench the gas-carburized object 5 by reheating it after cooling and then rapidly cooling it. Secondary quenching may be performed by rapidly cooling the primary cooling.
  • the atmosphere in which the quenching is performed is preferably a neutral protective atmosphere, that is, an atmosphere in which the material to be treated is not carburized or decarburized at that temperature, but may be an atmosphere of another inert gas or the like.
  • the reheating temperature for quenching is higher than the temperature at which at least the surface layer of the processing object 5 becomes austenite beyond the GS line or ES line in the equilibrium diagram shown in FIG. Example 1
  • the limit carburizing conditions were determined in advance by the gas carburizing method of the embodiment of the present invention, and gas carburizing was performed under the carburizing conditions set so as not to go against the limit carburizing conditions.
  • the object 5 to be treated is made of nickel-chromium-molybdenum steel (Japanese Industrial Standard SNCM420) and has a cylindrical shape with a diameter of 1 Omm and a length of 52 mm.
  • the carburized object 5 is naturally cooled in a vacuum vessel 1, quenched, polished, and finished with a diamond paste having a particle diameter of 3 zim, and then subjected to hardness measurement and The tissue was observed. Before carburizing, the inside of the vacuum vessel 1 was purged.
  • Carburizing gas is methane gas and diluent gas is nitrogen gas.
  • a gas for carburizing atmosphere was flowed into the vacuum vessel 1 at a constant flow rate of 0.5 L / min.
  • the quenching was performed by holding the object 5 in a quartz tube furnace at 860 ° C. in a nitrogen gas atmosphere for 10 minutes and then cooling it with oil.
  • Fig. 7 shows the results of the carburizing condition of 1 to 50 ° C, carburizing time of 1 minute, and carburizing conditions of the gas carburizing under the carburizing conditions of 40 V o 1% corresponding to the partial pressure of carburizing gas methane.
  • the relationship between the distance from the surface (mm) and the hardness (Hv) is shown.
  • the target value of the surface carbon concentration of the object 5 was set to 1.4% by weight.
  • Figure 8 shows the distance from the surface of the object to be carburized under the conditions of carburizing temperature of 1300 ° C, carburizing time of 1 minute, carburizing gas methane concentration of 10 V o 1% and carburizing conditions (mm). It shows the relationship between hardness and hardness (Hv). In this case, the target value of the surface carbon concentration of the treatment object 5 was 1.1.5% by weight.
  • Fig. 9 shows the surface of the object 5 to be carburized under a carburizing condition of 1250 ° C, a carburizing time of 10 minutes, and a carburizing gas concentration of 10 V o 1% corresponding to the partial pressure of methane as the carburizing gas. It shows the relationship between the distance (mm) from hardness and the hardness (Hv). In this case, the target value of the surface carbon concentration of the treatment object 5 was set to 1.4% by weight.
  • Figure 10 shows the distance (mm) and hardness from the surface of the gas-carburized object under carburizing conditions of 1300 ° C, carburizing time of 10 minutes, and carburizing gas methane concentration of 3 vo 1%. (Hv).
  • the target value of the surface carbon concentration of the object 5 was 1.15% by weight.
  • the carburizing time is 1 to 10 minutes and that a carburized layer with a sufficient effective carburizing depth can be obtained.
  • the partial pressure of methane which is the carburizing gas, is a value obtained by multiplying the total pressure of the carburizing atmosphere by the concentration of methane. In the examples shown in Figs. 7 to 10, the total pressure of the carburizing atmosphere was about 80 kPa.
  • a carburizing temperature of 130 O: and a metal structure before quenching of the surface layer of the object 5 subjected to gas carburizing at a carburizing time of 1 minute are shown in FIG. 11, and a metal structure after quenching is shown in FIG. 12. .
  • the coarse structure existing before quenching does not exist after quenching, and it can be confirmed that the coarse structure is refined by quenching.
  • the gas carburizing was performed under the carburizing conditions set by the gas carburizing method according to the embodiment of the present invention.
  • the processing object 5 is made of the same nickel-chromium-molybdenum steel (Japanese Industrial Standard SNCM420) as in the above embodiment, and has a cylindrical shape with a diameter of 10 mm and a length of 52 mm. Have.
  • the object 5 was naturally cooled in the vacuum vessel 1 without going through the diffusion process, quenched, polished, and finished with a diamond paste having a particle size of 3 jtim. Before carburizing, the inside of the vacuum vessel 1 was purged.
  • Carburizing gas is methane gas
  • diluent gas is nitrogen gas.
  • the quenching was performed by holding the object to be treated 5 in a quartz tube furnace at 860 under a nitrogen gas atmosphere for 10 minutes and then oil-cooling.
  • Carburizing temperature is 1300 ° C
  • carburizing time is 1 minute
  • the concentration corresponding to the partial pressure of methane, which is the carburizing gas in the carburizing atmosphere is 10 V o 1%
  • the target surface carbon concentration of the treatment object 5 The value was 0.74% by weight
  • the total pressure of the carburizing atmosphere was 8 OkPa
  • the gas for the carburizing atmosphere was flown into the vacuum vessel 1 at a constant flow rate of 0.5 L Zmin during carburizing.
  • the surface carbon concentration of the object 5 to be treated can be set to the target value without passing through the diffusion treatment step, and a sufficient carburizing depth can be obtained.
  • the carburizing time can be significantly reduced by increasing the carburizing temperature, and the carbon concentration in the surface layer of the object 5 does not exceed the set target value, so that the carbon diffusion process is unnecessary. Therefore, productivity can be improved.
  • the present invention is not limited to the above embodiments and examples, and various modifications can be made within the scope of the present invention.

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  • Engineering & Computer Science (AREA)
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  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)

Abstract

L'invention porte sur un procédé de cémentation gazeuse dans lequel la cémentation est réalisée à une température non supérieure à un point péritectique provoquant une transformation du fer delta et de la phase liquide en fer gamma, mais pas inférieure à un point eutectique provoquant une transformation de la phase liquide en fer gamma et en cémentite. En particulier, le procédé consiste à déterminer à l'avance des conditions de cémentation critiques telles que la couche superficielle d'un échantillon en acier d'un objet de traitement dans une atmosphère de cémentation soit austénitisée sans fusion. Le procédé comprend aussi une étape de cémentation gazeuse de l'objet de traitement, dans des conditions de cémentation définies de façon à être conformes aux conditions de cémentation critiques, à une température de cémentation non supérieure au point péritectique, mais pas inférieure au point eutectique. Les conditions de cémentation critiques prennent en compte la valeur limite supérieure de la pression partielle du gaz de cémentation dans laquelle la couche superficielle de l'échantillon est austénitisée sans fusion.
PCT/JP2003/005422 2002-06-11 2003-04-28 Procede de cementation gazeuse WO2003104516A1 (fr)

Priority Applications (6)

Application Number Priority Date Filing Date Title
AU2003235955A AU2003235955A1 (en) 2002-06-11 2003-04-28 Method of gas carburizing
EP03723223A EP1598440B1 (fr) 2002-06-11 2003-04-28 Procede de cementation gazeuse
JP2004511572A JP3696614B2 (ja) 2002-06-11 2003-04-28 ガス浸炭方法
US10/487,398 US7416614B2 (en) 2002-06-11 2003-04-28 Method of gas carburizing
KR1020047002043A KR100592757B1 (ko) 2002-06-11 2003-04-28 가스 침탄 방법
DE60333039T DE60333039D1 (de) 2002-06-11 2003-04-28 Gasaufkohlungsverfahren

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
PCT/JP2002/005767 WO2003104515A1 (fr) 2002-06-11 2002-06-11 Procede de cementation gazeuse
JPPCT/JP02/05767 2002-06-11
JP2002342505 2002-11-26
JP2002-342505 2002-11-26

Publications (1)

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WO2003104516A1 true WO2003104516A1 (fr) 2003-12-18

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PCT/JP2003/005422 WO2003104516A1 (fr) 2002-06-11 2003-04-28 Procede de cementation gazeuse

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EP (1) EP1598440B1 (fr)
JP (1) JP3696614B2 (fr)
KR (1) KR100592757B1 (fr)
CN (1) CN1257305C (fr)
AU (1) AU2003235955A1 (fr)
DE (1) DE60333039D1 (fr)
WO (1) WO2003104516A1 (fr)

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EP1493829A1 (fr) * 2003-07-03 2005-01-05 Koyo Thermo Systems Co., Ltd. Procédé de carburation gazeux
JP2005350729A (ja) * 2004-06-10 2005-12-22 Ishikawajima Harima Heavy Ind Co Ltd 真空浸炭方法
JP2021088748A (ja) * 2019-12-05 2021-06-10 株式会社日本テクノ ガス浸炭方法およびガス浸炭装置

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CN1304624C (zh) * 2005-03-29 2007-03-14 大连华锐股份有限公司 机械零件表面补碳的工艺方法
US8123872B2 (en) * 2006-02-22 2012-02-28 General Electric Company Carburization process for stabilizing nickel-based superalloys
CN113385763B (zh) * 2021-07-14 2022-08-26 成都共益缘真空设备有限公司 一种真空回流焊正负压结合焊接工艺

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Publication number Priority date Publication date Assignee Title
EP1493829A1 (fr) * 2003-07-03 2005-01-05 Koyo Thermo Systems Co., Ltd. Procédé de carburation gazeux
US7029540B2 (en) 2003-07-03 2006-04-18 Koyo Thermo Systems Co., Ltd. Method of gas carburizing
JP2005350729A (ja) * 2004-06-10 2005-12-22 Ishikawajima Harima Heavy Ind Co Ltd 真空浸炭方法
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JP2021088748A (ja) * 2019-12-05 2021-06-10 株式会社日本テクノ ガス浸炭方法およびガス浸炭装置
JP7189115B2 (ja) 2019-12-05 2022-12-13 株式会社日本テクノ ガス浸炭方法およびガス浸炭装置

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KR100592757B1 (ko) 2006-06-26
AU2003235955A1 (en) 2003-12-22
KR20040106279A (ko) 2004-12-17
EP1598440B1 (fr) 2010-06-16
JPWO2003104516A1 (ja) 2005-10-06
EP1598440A1 (fr) 2005-11-23
CN1257305C (zh) 2006-05-24
EP1598440A4 (fr) 2008-06-18
CN1545566A (zh) 2004-11-10
DE60333039D1 (de) 2010-07-29
JP3696614B2 (ja) 2005-09-21

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