EP3802904A1 - Procédé de cémentation basse pression d'une pièce comprenant de l'acier - Google Patents
Procédé de cémentation basse pression d'une pièce comprenant de l'acierInfo
- Publication number
- EP3802904A1 EP3802904A1 EP19735366.7A EP19735366A EP3802904A1 EP 3802904 A1 EP3802904 A1 EP 3802904A1 EP 19735366 A EP19735366 A EP 19735366A EP 3802904 A1 EP3802904 A1 EP 3802904A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- carbon
- gas
- carburizing
- steel
- bar
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 42
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 30
- 239000010959 steel Substances 0.000 title claims abstract description 30
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 70
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 69
- 238000002347 injection Methods 0.000 claims abstract description 21
- 239000007924 injection Substances 0.000 claims abstract description 21
- 230000007423 decrease Effects 0.000 claims abstract description 4
- 239000007789 gas Substances 0.000 claims description 57
- 238000005255 carburizing Methods 0.000 claims description 42
- 238000009792 diffusion process Methods 0.000 claims description 32
- 230000007935 neutral effect Effects 0.000 claims description 29
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 24
- 239000011651 chromium Substances 0.000 claims description 16
- 238000001816 cooling Methods 0.000 claims description 14
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 10
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 8
- 229910052804 chromium Inorganic materials 0.000 claims description 8
- 238000010790 dilution Methods 0.000 claims description 8
- 239000012895 dilution Substances 0.000 claims description 8
- 229910052759 nickel Inorganic materials 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 6
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 claims description 6
- 239000010941 cobalt Substances 0.000 claims description 6
- 229910017052 cobalt Inorganic materials 0.000 claims description 6
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 5
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 4
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 claims description 3
- 239000001294 propane Substances 0.000 claims description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 13
- 229910001566 austenite Inorganic materials 0.000 description 8
- 229910000767 Tm alloy Inorganic materials 0.000 description 6
- 229910052742 iron Inorganic materials 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 5
- 229910052750 molybdenum Inorganic materials 0.000 description 5
- 239000011733 molybdenum Substances 0.000 description 5
- 238000010926 purge Methods 0.000 description 5
- 238000011282 treatment Methods 0.000 description 5
- 230000008030 elimination Effects 0.000 description 3
- 238000003379 elimination reaction Methods 0.000 description 3
- 229930195733 hydrocarbon Natural products 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- GQPLMRYTRLFLPF-UHFFFAOYSA-N nitrous oxide Inorganic materials [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- -1 C2H2 hydrocarbon Chemical class 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000001721 carbon Chemical class 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000005294 ferromagnetic effect Effects 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
Classifications
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
-
- 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
- C23C8/80—After-treatment
Definitions
- the present invention relates to a low-pressure carburizing process of a workpiece comprising steel.
- carburizing means a conventional process in the field of metallurgy. It is a thermochemical treatment consisting in the superficial penetration of carbon (C) into a steel piece in order to transform it, on the surface, into a highly carburized steel.
- a steel alloy is a metal alloy consisting mainly of iron (Fe) and carbon (ranging, for carbon (C), from a mass ratio close to 0%, corresponding to minute traces, up to a rate of 2% ).
- the carbon content has a considerable influence on the properties of the steel. Below 0.008% carbon (C), for example, steel is rather malleable and is called "iron".
- the carbon content (C) in particular profoundly modifies the melting point and the mechanical properties of the steel.
- Increasing the carbon content of a steel improves the hardness (a surface resistance to penetration of a tip) of the steel and decreases its elongation at break. Increasing the surface carbon content thus makes it possible to increase the surface mechanical properties of the part, and to increase its resistance to wear and its endurance.
- CBP low pressure gas carburizing
- low pressure carburizing is meant a carburization process carried out in a vacuum furnace with cold walls, which uses gaseous hydrocarbons at low pressure: 2 to 20 mbar absolute, for example 10 mbar, and at elevated temperature.
- Infracarb® process of ECM Technologies is the patented process used in our Modular Facility for Cementation and Treatments.
- Infracarb® consists of an alternating injection of C2H2 hydrocarbon, to create a surface enrichment by cracking molecules at high temperature and a neutral gas N2 for diffusion.
- the difficulty of CBP carburizing lies in the limitation of the carbon diffusion depth, especially during the cementation of materials very sensitive to the presence of carbon, such as Ferrium ® C61 TM and Ferrium ® C64 TM alloys. marketed by the company Questek, and for which it is not necessary to exceed a rate of 0.5% carbon (C) on the surface.
- Ferrium® C61 TM and C64 TM alloys differ from conventional compositions (for example compositions comprising 0.16% carbon (C), 3% nickel (Ni), less than 1% chromium ( Cr) and traces of molybdenum (Mo) by higher levels of carbon (C) and gammagens: for example, rates of the order of 0.2% carbon (C), 9% nickel (Ni) ), 3.5% chromium (Cr) and 1% molybdenum (Mo).
- conventional compositions for example compositions comprising 0.16% carbon (C), 3% nickel (Ni), less than 1% chromium ( Cr) and traces of molybdenum (Mo) by higher levels of carbon (C) and gammagens: for example, rates of the order of 0.2% carbon (C), 9% nickel (Ni) ), 3.5% chromium (Cr) and 1% molybdenum (Mo).
- the gamma-containing elements including cobalt (Co), nickel (Ni), nitrogen (N) and copper (Cu), are addition elements that increase the stability range of a particular iron allotrope: austenite.
- Austenite allows a high solubility of carbon.
- the vast majority of so-called stainless steels are austenitic and they combine good corrosion resistance with high mechanical properties.
- Ferrium® C61 TM and Ferrium® C64 TM alloys also have a higher level of alphagenic elements, such as molybdenum (Mo) and chromium (Cr).
- the alphagenes elements tend, for their part, to destabilize austenite, in favor of ferrite.
- Ferrite is an allotrope of steel that dissolves carbon poorly (C) and has ferromagnetic properties at low temperatures.
- C carbon poorly
- these ferric precipitates take the form of carbides forming networks that locally strengthen the hardness of the room but weaken the room as a whole.
- the desired properties are particularly dependent on variations in the metallographic structure and the surface carbon content (C). These two characteristics depend directly on the thermochemical treatments put in place during the cementation processes. Obtaining a structure having the characteristics necessary for the proper use of the part therefore depends directly on the parameters defined during the cementation.
- the invention aims to achieve this goal. It thus proposes a low-pressure carburizing process adapted to steel parts comprising alphagenes and gamma-gen elements. STATEMENT OF THE INVENTION
- the invention thus relates to a low-pressure carburizing process of a part comprising, especially at the surface, steel, said steel comprising, in percentage by weight:
- Ni nickel
- a cementing gas injection step referred to herein as a "carburizing step", in the carburizing chamber, so as to enrich the surface of the part with carbon and to increase the surface carbon content of the the piece up to a predetermined upper surface area, the cementing gas being injected into the chamber at a flow rate of between 1000 Nl / h and 3000 Nl / h, the temperature of the chamber being between 950 ° C and 1050 ° C, and for a period of between 30 and 250s, and
- a step of injecting a neutral gas into the carburizing chamber so as to diffuse the carbon from the surface towards the interior of the room, and to decrease the surface carbon content of the room up to at a predetermined lower surface area
- the neutral gas injection stage comprising a first neutral gas injection phase, at a flow rate of between 1000 and 10,000 Nl / h, and for a period of between 5 and 60 seconds, followed by a second neutral gas injection phase, at a flow rate of between 500 Nl / h and 3000 Nl / h, and for a period of between 10 and 2000s.
- This allows a carburizing under an inert atmosphere, particularly under partial pressure of neutral gas (eg nitrous (N2)) and no longer under vacuum.
- the diffusion is thus carried out under partial pressure of neutral gas after a purge phase using a high flow rate of neutral gas). In this way, healthy structures are obtained which are free of intergranular precipitates forming networks and having an acceptable residual austenite content.
- the injection step therefore allows carbon enrichment (C), and the diffusion step allows dilution and diffusion of this carbon enrichment (C) in the austenite so as to reach the desired depth.
- This diffusion thus avoids supersaturation on the surface and the precipitation of carbon (C) which can eventually lead to soot deposits harmful to the enrichment of steel.
- the method according to the invention may comprise one or more of the features or steps below, taken separately from one another or in combination with each other:
- the predetermined upper surface carbon content is the same for all the cycles
- the cementing gas is chosen from propane (C 3 H 8 ) and acetylene (C 2 H 2 ),
- the cementing gas has a dilution ratio of between 0 and 75%, a very low dilution rate being preferred for the high depths of carburizing and while a very high dilution rate is preferred for the (very) weak depths of carburizing, the cementing gas is injected at a pressure of between 0.1 bar and 3 bar, taking care to respect a corresponding enclosure pressure,
- the neutral gas is chosen from dinitrogen (N 2 ) and argon (Ar),
- the neutral gas is injected at a pressure of between 0.1 and 7 bar and
- the process comprises a final diffusion step followed by a cooling step during which the cooling rate is between 7 ° C./min and 200 ° C./min,
- the cooling step following the final diffusion step is carried out outside the carburizing chamber, in a dedicated cooling cell.
- the mass of carbon (C) surface, at the end of the cooling step, is between [0.4] and [0.6]%.
- the pressure in the carburising enclosure of between 0.002 bar and 0.025 bar, the pressure increase aimed at improving the cementation of confined zones;
- the piece is made of said steel.
- FIG. 1 is a diagram of a low pressure carburizing chamber in which is deposited a part to be cemented according to the method of the present invention
- FIG. 2 is a schematic diagram of the mass ratio of carbon (C) present on the surface of a part subjected to a low pressure carburizing process according to the invention, as a function of time,
- FIG. 3 is a graphical representation of the mass ratio of carbon (C) present in the part as a function of the distance of the surface to the core of said piece, and at different stages of a cycle of the method according to the invention, for a sample of pure iron.
- a part 1 comprising or consisting of a steel comprising alphagenes and gammagenes elements, said steel comprising, for example, in percent by weight:
- Ni nickel
- the method preferably applies to a part 1 comprising or consisting of an alloy of Ferrium® C61 TM and Ferrium® C64 TM type.
- Ferrium® C61 TM alloy is a steel of composition:
- the Ferrium® C64 TM alloy is a steel of composition:
- the test alloy is pure iron.
- the method according to the invention consists of one or more successive cycles. In the example illustrated in FIG. 2, it implements a succession of four cycles C1, C2, C3, C4.
- Each cycle C1, C2, C3, C4 comprises a step 10 for injecting a carburizing gas, for example propane (C 3 H 8) or acetylene (C2H2), followed by a step 12 of injection a neutral gas, for example argon (Ar) or dinitrogen (N 2 ).
- a neutral gas for example argon (Ar) or dinitrogen (N 2 ).
- This is a step 12 of diffusion under partial pressure of a neutral gas.
- each step of injection of the cementing gas is directly followed by the step 12 of injecting neutral gas.
- the method firstly comprises a step of placing the workpiece 1 in a carburizing chamber 2, as shown in FIG. 1.
- This carburizing chamber 2 comprises in particular a gas inlet 3 and an outlet of gas 4 and can be closed tightly and isothermally.
- the first step of each cycle C1, C2, C3, C4 is a cementing gas injection step 10 (also called a carbon enrichment step) in the enclosure of This enrichment step has a duration ti of between 30 and 250 seconds, preferably between 50 and 150 seconds.
- the duration ti of the enrichment step 10 is a function of a predetermined surface carbon (C), which is ultimately aimed at (that is to say, a temperature intended for be reached at the end of the process) on the surface of the piece 1.
- surface here means a depth substantially zero, preferably zero. Under optimal conditions, this higher surface level may correspond to the carbon solubility limit (C) in the austenite at the given carburizing temperature.
- This surface rate upper 14 is typically greater than the initial carbon (C) level 16 of the part 1 to be treated.
- the cementing gas is injected into the carburizing chamber 2 at a flow rate of between 1000 Nl / h and 3000 Nl / h (preferably between 1300 and 1700 Nl / h), the carburizing temperature being between 950 ° C and 1050 ° C (and preferably equal to 1000 ° C ⁇ 10 ° C).
- the unit Nl / h is a normo liter per hour.
- Normo liter is derived from normo cubic meter.
- the normo cubic meter, of symbol Nm3 or sometimes m3 (n), is a unit of measure of quantity of gas which corresponds to the contents of a volume of one cubic meter, for a gas being in the normal conditions of temperature and humidity. pressure (0 or 15 or rarely 20 ° C according to the standards and 1 atm, 101 325 Pa).
- the dilution ratio of the cementing gas injected is between 0 and 75%, preferably between 0 and 25%, and the cementing gas is injected at a pressure of between 0.1 bar and 3 bar, preferably equal to 230 ⁇ 50 mbar.
- concentration ratio is meant here a dilution of the cementing gas in a neutral gas, typically the neutral gas argon (Ar) or nitrous (N2).
- the enrichment step 10 there is a partial or total saturation of the austenite on the surface of the steel piece.
- the desired maximum carbon (C) content at the end of the enrichment step depends on the grade of steel as well as the temperature at which the carburizing is carried out.
- FIG. 3 represents the carbon profile of a part 1 subjected to the process according to the invention, that is to say the mass ratio of carbon present in the part 1 as a function of the distance of the surface towards the core of said piece 1, that is to say the depth of the piece 1.
- Figure 3 illustrates both a carbon (C) 18 (dashed) at the end of step 10 enrichment, before the start of the diffusion step 12, and a carbon content (C) (solid line) at the end of the diffusion step 12.
- the degree of carbon (C) 18 as a function of the depth at the end of the enrichment stage exhibits a substantially exponential decay: at the surface of the part, the carbon (C) 18 and very high, while at a depth of 0.2 mm, this rate 18 is equal to a value close to 0 (in the case of the pure iron sample used for the measurements shown in FIG. 3).
- the second step of each cycle C1, C2, C3, C4 is a diffusion step 12.
- This diffusion step 12 takes place under a neutral atmosphere and thus requires, as indicated above, the injection of a neutral gas such as dinitrogen (N 2 ) or argon (Ar) in the carburizing chamber 2.
- a neutral gas such as dinitrogen (N 2 ) or argon (Ar) in the carburizing chamber 2.
- N 2 dinitrogen
- Ar argon
- the diffusion step 12 consists of two phases: a purge phase of the cementing gas with a duration t 2 of between 5 and 60s (preferably 10 ⁇ 5s), and a diffusion phase of strictly speaking, of a duration t 3 of between 10 and 2000s (preferably 30 to 2000s).
- the duration of the diffusion step 12 is therefore, as can be seen in FIG. 2, from (t 2 + t 3 ).
- the values t 1, 2 2 h were taken to be identical for simplification. In fact, depending on the fineness of treatment desired, they are often called to be modified (adjusted) from one cycle C1, C2, C3, C4 to another.
- the difference between the two phases of the diffusion step 12 lies in the injection rate of the neutral gas.
- the neutral gas is injected into the carburizing chamber 2 at a flow rate of between 1000 and 10,000 Nl / h, preferably equal to 6000 ⁇ 500 Nl / h, at a gas pressure.
- neutral in the chamber 2 between 0.1 and 7 bar, preferably equal to 230 ⁇ 50 mbar.
- the neutral gas is injected at a flow rate of between 500 Nl / h and 3000 Nl / h, preferably equal to 1800 ⁇ 500 Nl / h, the pressure in the carburizing chamber 2 being between 2 and 25 mbar, preferably between 7 and 13 mbar.
- the carbon content (C) as a function of the depth of the piece 1 substantially has a plateau, for a depth from 0 to 0.1 mm, before decreasing to a level equal to a value close to 0 (for the pure iron sample whose values are shown in FIG. 3) for a depth of 0.2 mm.
- the predetermined lower surface carbon concentration (C) 22 at the end of the diffusion step 12 (comprising a purge phase and a diffusion phase) is lower than the higher carbon (C) surface 14 which had been obtained at the end of the enrichment step 10.
- This predetermined lower surface area may, however, be greater than the initial surface area.
- the lower surface area corresponds neither to physical value, nor to a characteristic of the material, nor to a fixed or controlled value.
- the value of this lower surface rate 22 is obtained downstream from the setting modalities.
- a change in the number of cycles impacts the maximum carbon level (C) 14 desired and the predetermined lower surface area 22, as well as the total diffused depth and the final carbon profile.
- a final diffusion step 24 and then a cooling step are carried out.
- the cooling can be performed outside the carburizing chamber 2, in a dedicated cooling cell (not shown). Cooling gradually reduces the temperature of the workpiece 1 from its carburizing temperature to a temperature specific to the handling of the workpiece 1.
- the cooling rate of the carburizing enclosure 2 or the dedicated enclosure is included between 7 ° C / min and 200 ° C / min, preferably 120 ⁇ 50 ° C / min.
- the final surface carbon (C) content 26 is lower than the lower carbon (C) level 22 obtained at the end of diffusion step 12, but it may be greater than the rate 16 as shown in Figure 2.
- the final surface carbon (C) content 26 aims to be as close as possible to the theoretical optimum surface area (0.5% by weight for Ferrium steels).
- the target surface 22 and higher target surface rates 14 and 14 result from the physical parameters of the component 1 to be cemented and those of the carburizing enclosure 2 used.
- thermochemical treatments of the treated part 1 make it possible to obtain different thermochemical treatments of the treated part 1. These differences relate in particular to the cemented depth and the type of cemented structure obtained.
- the shape of the cemented part 1 (for example parts having teeth) must also be taken into account when adjusting the parameters of the carburizing process.
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1854876A FR3081884B1 (fr) | 2018-06-05 | 2018-06-05 | Procede de cementation basse pression d'une piece comprenant de l'acier |
PCT/FR2019/051338 WO2019234352A1 (fr) | 2018-06-05 | 2019-06-05 | Procédé de cémentation basse pression d'une pièce comprenant de l'acier |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3802904A1 true EP3802904A1 (fr) | 2021-04-14 |
Family
ID=63896272
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19735366.7A Pending EP3802904A1 (fr) | 2018-06-05 | 2019-06-05 | Procédé de cémentation basse pression d'une pièce comprenant de l'acier |
Country Status (5)
Country | Link |
---|---|
US (1) | US11293087B2 (fr) |
EP (1) | EP3802904A1 (fr) |
CN (1) | CN112218970A (fr) |
FR (1) | FR3081884B1 (fr) |
WO (1) | WO2019234352A1 (fr) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN113502449A (zh) * | 2021-06-04 | 2021-10-15 | 中航力源液压股份有限公司 | 一种15Cr14Co12Mo5Ni2VW高强度不锈钢低压渗碳热处理方法 |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4306919A (en) * | 1980-09-04 | 1981-12-22 | Union Carbide Corporation | Process for carburizing steel |
FR2678287B1 (fr) * | 1991-06-26 | 1993-10-29 | Etudes Constructions Mecaniques | Procede et four de cementation a basse pression. |
FR2801059B1 (fr) | 1999-11-17 | 2002-01-25 | Etudes Const Mecaniques | Procede de trempe apres cementation a basse pression |
US6547888B1 (en) * | 2000-01-28 | 2003-04-15 | Swagelok Company | Modified low temperature case hardening processes |
FR2821362B1 (fr) * | 2001-02-23 | 2003-06-13 | Etudes Const Mecaniques | Procede de cementation basse pression |
DE10254846B4 (de) * | 2002-11-25 | 2011-06-16 | Robert Bosch Gmbh | Verfahren zum Einsatzhärten von Bauteilen aus Warmarbeitsstählen mittels Unterdruckaufkohlung |
US7208052B2 (en) * | 2003-12-23 | 2007-04-24 | Rolls-Royce Corporation | Method for carburizing steel components |
FR2884523B1 (fr) * | 2005-04-19 | 2008-01-11 | Const Mecaniques Sa Et | Procede et four de carbonitruration a basse pression |
US8696830B2 (en) * | 2010-07-21 | 2014-04-15 | Kenneth H. Moyer | Stainless steel carburization process |
FR3029938B1 (fr) * | 2014-12-11 | 2019-04-26 | Ecm Technologies | Procede et four de carbonitruration a basse pression |
EP3277857B1 (fr) * | 2015-04-02 | 2021-05-05 | Sikorsky Aircraft Corporation | Cémentation de composants d'acier |
-
2018
- 2018-06-05 FR FR1854876A patent/FR3081884B1/fr active Active
-
2019
- 2019-06-05 EP EP19735366.7A patent/EP3802904A1/fr active Pending
- 2019-06-05 CN CN201980037596.3A patent/CN112218970A/zh active Pending
- 2019-06-05 WO PCT/FR2019/051338 patent/WO2019234352A1/fr unknown
- 2019-06-05 US US15/734,542 patent/US11293087B2/en active Active
Also Published As
Publication number | Publication date |
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CN112218970A (zh) | 2021-01-12 |
WO2019234352A1 (fr) | 2019-12-12 |
FR3081884A1 (fr) | 2019-12-06 |
US11293087B2 (en) | 2022-04-05 |
US20210230732A1 (en) | 2021-07-29 |
FR3081884B1 (fr) | 2021-05-21 |
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