CA1258609A - Shallow case hardening process - Google Patents
Shallow case hardening processInfo
- Publication number
- CA1258609A CA1258609A CA000489938A CA489938A CA1258609A CA 1258609 A CA1258609 A CA 1258609A CA 000489938 A CA000489938 A CA 000489938A CA 489938 A CA489938 A CA 489938A CA 1258609 A CA1258609 A CA 1258609A
- Authority
- CA
- Canada
- Prior art keywords
- order
- magnitude
- preferred
- furnace
- workpieces
- 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.)
- Expired
Links
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
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/34—Methods of heating
- C21D1/53—Heating in fluidised beds
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Abstract
SHALLOW CASE HARDENING PROCESS
Abstract of Disclosure A shallow case hardening process comprising passing selected mixtures of gases for proscribed times through sand in which workpieces are imbedded at temperatures substantially different from recommended levels in normal nitriding.
Abstract of Disclosure A shallow case hardening process comprising passing selected mixtures of gases for proscribed times through sand in which workpieces are imbedded at temperatures substantially different from recommended levels in normal nitriding.
Description
Specifications In the past, it has been a common practice in hea-t trea-ting of metal workpieces to utilize f]uid beds, such as -those made by Procedyne 10 Corporation of New Brunswick, New Jersey. An example of these ~fluidized beds is designated 1~3502048HT, standing respectively for: 1850 degrees Fahrenheit, 20 inch diameter, 4~3 inch depth.
These are, essentially, Furnaces that have a sand-like bed, where the sand is made of aluminum oxide. Diffusion plates are 15 underneath the sand, in the sense that the top of a coffee perco]ator has ]itt]e holes in it for dif-fusing water, except that the holes in this case are filled wi-th small screws that are countersunk but not entirely screwed in, and they are oversized holes with respect to the shafts of the countersunk screws, so tha-t a small 20 passageway is created for flow of gasses -through the diffusion plate underneath the bed of aluminum oxide.
These fluidized beds are utilized to facili-tate carborizing, ni trocarborizing, carbonitriding, and nitro-hardening . In the case of nitro-hardening, temperatures of approximately 1500 degrees 25 Fahrenheit are -utilized, in an Austenitizing type process, to provide core-hardening as opposed to case-hardening of parts. As to carborizing, temperatures of approximately 1750 degrees $~
.
Fahrenheit are utilized to provide case-hardening at a high temperature with high carbon content. Nitrocarborizing refers to providing case-hardening with a relatively larger n;trogen con-tent at temperatures of approximately 1050 degrees Fahrenheit.
5 Carbonitriding is provided at -tempera-tures oE approximately 1600 degrees Fahrenheit for a higher carbon conten-t of the mixture of carbon and nitrogen in providing the case-hardening for high Rockwells at surface. Nitrocarborizing is a light case process a-t low -temperature, high surface hardnesses, and not a lot of depth;
10 the opposite is -true of carbonitriding, wi-th a higher -temperature, and a deeper case hardening. Carborizing is 60 thousandths deep, carbonitriding is 15 to 20 thousandths deep, and nitrocarborizing is 3 to 5 thousandths deep.
Another process for finishing metal is -the Quench-Polish-Quench (or 15 Q . P . Q . ) Process for applying corrosion resistance . The Q . P . Q .
Process, is in part inadequate, because, while it provides excellent corrosion characteristics, it destroys -the hardening charac teristics required, and this has dramatic results affecting tool life and possible failure.
20 Past experience with the Procedyne Process in the way it has been utilized provides excellen-t increases in Rockwell and case-hardening, as opposed to core-hardening. Prior to the subject inven-tion, it had not been considered using processes analogous -to -the Procedyne Process for achieving not only case-hardening but, 25 simultaneously, corrosion resistance.
Accordingly, it is an object of this invention to combine the -two objectives and manipulate and change parame-ters involving gas Elow and tempera-ture, for ob-taining simul taneously -the appropriate corrosion resis-tance and case-hardening for -the particular product.
- ::
6~
Previous to this time, a blanket rule of thumb had been recommended by procedyne, and u-tilized throughout the industry, which was a s-tandard half-hour sa-tura-tion in the bed at fluid Elows of approximately, or a leas-t not exceeding 800 cubic feet per hour.
5 This cookbook was a s-tandard flow, standard diffusion at the end of the cycle, standard temperature, and standard -time within the furnace prior to diffusion: -two hours in a ni-trocarborizing atmosphere, one half hour diffusion time, 800 cubic feet per hour to-tal gas flows---its various components are as follows: 35%
ammonia, 45% natural 0as, 10% ni-trogen.
It is another object of this invention -to achieve case hardening and corrosion resis-tance in an integral heat--treating process in an uncomplicated, inexpensive, readily utilizable manner.
These and other objects of -this inven-tion may be more readily 15 understood from the following specifications and claims.
This invention relates generally to nitrocarborizing, carborizing and the like, and more par-ticularly, i-t relates -to case-hardening with corrosion resistance characteristics achieved by passing gas through a bed of sand a-t specified ra-tes of flow, type of gas, time 20 prior to diffusion, and diffusion time, and tempera-ture.
For example, in making parts, specifically a chain for a front-wheel drive, the time is 3 hours in ni-trogen and other gas atmosphere.
800 pounds of workpieces will be dropped into the furnace. I~ will -take about a hal-f hour for -the furnace to res-tore its initial 25 temperature of 980 degrees Fahrenhei-t. The preferred gas atmosphere is then introduced. I-t comprises -the following: at the ra-te of 250 cubic feet of nitrogen per hour, 700 cubic fee-t of ammonia per hour, 350 cubic fee-t of natural gas per hour; held at .~5~
temperature at those atmospheres for 3 hours. This phase is followed by an hour and a half of humidified nitrogen.
E~umidified nitrogen is obtained by passing dry nitrogen through a humidifier, in a manner well known in the humidifying art.
5 Nitrogen, being hygroscopic, absorbing moisture through a humidifier, then is passed through the bed a-t 300 cubic feet an hour, humidified -to approximately 10 to 20 percent. This forms an oxidized layer on top of the previous ni-trocarborized layer. The oxide layer is highly porous, which allows for its lubrication 10 properties, and underneath it is the nitrocarbide layer, which is extremely non-porous. The depth of the oxide layer is approximately 5 tenths of a thousandth of an inch. White layer is between one and one-and-one-half thousandths pure nitrogen.
Below that is six thousandths of diffused nitrogen zone.
15 This contrasts with the Procedyne process described above, where there would be no oxide layer, white layer would be one to two-tenths of a thousandths of an inch, nitride layer would be two to -three thousandths.
This invention provides an extraordinarily deep loading of fifty to a 20 hundred times what it would ordinarily be of -the case-hardened depth, which gives significantly grea-ter hardening and corrosion resistant properties.
In an alternative embodiment of this invention, the parame ters would change for a cutting-type tool, such as an end mill, in which 25 temperature would be lowered (950 degrees Fahrenheit), atmosphere total flows woulà be the same, time in the atmosphere would be 30 minu-tes (a 30 minu-te diffuse on humidified nitrogen), i-t would give an oxide depth of 5 -tenths of a -thousandth, the white layer would ... . .
~%5~
be one to two ~enths of a thousandth, and a nitride layer of 5 to 7 tenths of a tho~lsandth. The oxide layer cuts down the welding effect of chips on the c-ltting edge.
These are, essentially, Furnaces that have a sand-like bed, where the sand is made of aluminum oxide. Diffusion plates are 15 underneath the sand, in the sense that the top of a coffee perco]ator has ]itt]e holes in it for dif-fusing water, except that the holes in this case are filled wi-th small screws that are countersunk but not entirely screwed in, and they are oversized holes with respect to the shafts of the countersunk screws, so tha-t a small 20 passageway is created for flow of gasses -through the diffusion plate underneath the bed of aluminum oxide.
These fluidized beds are utilized to facili-tate carborizing, ni trocarborizing, carbonitriding, and nitro-hardening . In the case of nitro-hardening, temperatures of approximately 1500 degrees 25 Fahrenheit are -utilized, in an Austenitizing type process, to provide core-hardening as opposed to case-hardening of parts. As to carborizing, temperatures of approximately 1750 degrees $~
.
Fahrenheit are utilized to provide case-hardening at a high temperature with high carbon content. Nitrocarborizing refers to providing case-hardening with a relatively larger n;trogen con-tent at temperatures of approximately 1050 degrees Fahrenheit.
5 Carbonitriding is provided at -tempera-tures oE approximately 1600 degrees Fahrenheit for a higher carbon conten-t of the mixture of carbon and nitrogen in providing the case-hardening for high Rockwells at surface. Nitrocarborizing is a light case process a-t low -temperature, high surface hardnesses, and not a lot of depth;
10 the opposite is -true of carbonitriding, wi-th a higher -temperature, and a deeper case hardening. Carborizing is 60 thousandths deep, carbonitriding is 15 to 20 thousandths deep, and nitrocarborizing is 3 to 5 thousandths deep.
Another process for finishing metal is -the Quench-Polish-Quench (or 15 Q . P . Q . ) Process for applying corrosion resistance . The Q . P . Q .
Process, is in part inadequate, because, while it provides excellent corrosion characteristics, it destroys -the hardening charac teristics required, and this has dramatic results affecting tool life and possible failure.
20 Past experience with the Procedyne Process in the way it has been utilized provides excellen-t increases in Rockwell and case-hardening, as opposed to core-hardening. Prior to the subject inven-tion, it had not been considered using processes analogous -to -the Procedyne Process for achieving not only case-hardening but, 25 simultaneously, corrosion resistance.
Accordingly, it is an object of this invention to combine the -two objectives and manipulate and change parame-ters involving gas Elow and tempera-ture, for ob-taining simul taneously -the appropriate corrosion resis-tance and case-hardening for -the particular product.
- ::
6~
Previous to this time, a blanket rule of thumb had been recommended by procedyne, and u-tilized throughout the industry, which was a s-tandard half-hour sa-tura-tion in the bed at fluid Elows of approximately, or a leas-t not exceeding 800 cubic feet per hour.
5 This cookbook was a s-tandard flow, standard diffusion at the end of the cycle, standard temperature, and standard -time within the furnace prior to diffusion: -two hours in a ni-trocarborizing atmosphere, one half hour diffusion time, 800 cubic feet per hour to-tal gas flows---its various components are as follows: 35%
ammonia, 45% natural 0as, 10% ni-trogen.
It is another object of this invention -to achieve case hardening and corrosion resis-tance in an integral heat--treating process in an uncomplicated, inexpensive, readily utilizable manner.
These and other objects of -this inven-tion may be more readily 15 understood from the following specifications and claims.
This invention relates generally to nitrocarborizing, carborizing and the like, and more par-ticularly, i-t relates -to case-hardening with corrosion resistance characteristics achieved by passing gas through a bed of sand a-t specified ra-tes of flow, type of gas, time 20 prior to diffusion, and diffusion time, and tempera-ture.
For example, in making parts, specifically a chain for a front-wheel drive, the time is 3 hours in ni-trogen and other gas atmosphere.
800 pounds of workpieces will be dropped into the furnace. I~ will -take about a hal-f hour for -the furnace to res-tore its initial 25 temperature of 980 degrees Fahrenhei-t. The preferred gas atmosphere is then introduced. I-t comprises -the following: at the ra-te of 250 cubic feet of nitrogen per hour, 700 cubic fee-t of ammonia per hour, 350 cubic fee-t of natural gas per hour; held at .~5~
temperature at those atmospheres for 3 hours. This phase is followed by an hour and a half of humidified nitrogen.
E~umidified nitrogen is obtained by passing dry nitrogen through a humidifier, in a manner well known in the humidifying art.
5 Nitrogen, being hygroscopic, absorbing moisture through a humidifier, then is passed through the bed a-t 300 cubic feet an hour, humidified -to approximately 10 to 20 percent. This forms an oxidized layer on top of the previous ni-trocarborized layer. The oxide layer is highly porous, which allows for its lubrication 10 properties, and underneath it is the nitrocarbide layer, which is extremely non-porous. The depth of the oxide layer is approximately 5 tenths of a thousandth of an inch. White layer is between one and one-and-one-half thousandths pure nitrogen.
Below that is six thousandths of diffused nitrogen zone.
15 This contrasts with the Procedyne process described above, where there would be no oxide layer, white layer would be one to two-tenths of a thousandths of an inch, nitride layer would be two to -three thousandths.
This invention provides an extraordinarily deep loading of fifty to a 20 hundred times what it would ordinarily be of -the case-hardened depth, which gives significantly grea-ter hardening and corrosion resistant properties.
In an alternative embodiment of this invention, the parame ters would change for a cutting-type tool, such as an end mill, in which 25 temperature would be lowered (950 degrees Fahrenheit), atmosphere total flows woulà be the same, time in the atmosphere would be 30 minu-tes (a 30 minu-te diffuse on humidified nitrogen), i-t would give an oxide depth of 5 -tenths of a -thousandth, the white layer would ... . .
~%5~
be one to two ~enths of a thousandth, and a nitride layer of 5 to 7 tenths of a tho~lsandth. The oxide layer cuts down the welding effect of chips on the c-ltting edge.
Claims (5)
1. In a heat treating method for surface treating metal workpieces utilizing gaseous entities flowing through a fluidized bed at temperatures substantially above the boiling point of moisture and substantially below the freezing point of the metal workpieces, the improvements comprising:
heating a fluidized bed furnace to a first temperature;
introducing workpieces into said furnace;
allowing the combined mass of the workpieces and the furnace to recover to said first temperature;
after said temperature recovery, introducing a first preferred atmosphere into said furnace; said first preferred atmosphere comprising ammonia; nitrogen; and natural gas;
maintaining said first preferred atmosphere in said furnace at said first temperature with said mass of workpieces for a first preferred period of time;
contacting said workpieces with a second preferred atmosphere in a fluidized bed furnace, said second preferred atmosphere comprising a humidified nitrogen mixture being introduced into said furnace;
and maintaining said second preferred atmosphere in said furnace with said mass of workpieces for a second preferred period of time.
2. The method of claim 1, wherein said first preferred period of time is of an order of magnitude corresponding about one to five hours and said second preferred period of time corresponds to an order of magnitude in the range of one-half to one and one half hours.
3. The method of Claim 1 wherein said first preferred period of time is of an order of magnitude corresponding about one to five hours and said second preferred period of time corresponds to an order of magnitude in the range of one-half to one and one half hours, and whereby each treated workpiece has an outer layer that is substantially porous and operable to hold a coating in measurable amounts and having a coefficient of friction substantially lower than the outer surface of said workpiece prior to subjection to said method.
4. The method of Claim 1 wherein said first preferred period of time is of an order of magnitude corresponding about one to five hours and said second preferred period of time corresponds to an order of magnitude in the range of one to one and one half hours, and whereby each treated workpiece has an outer layer that is substantially porous and operable to hold a coating in measurable amounts and having a coefficient of friction substantially lower than the outer surface of said workpiece prior subjection to said method; and a second layer adjacent said outer layer being substantially nonporous.
5. The method of Claim 1 wherein said first preferred period of time is of an order of magnitude corresponding to about one to five hours and said second preferred period of time corresponds to an order of magnitude in the range of one-half to one and one half hours, and whereby each treated workpiece has an outer layer that is substantially porous and operable to hold petroleum product in measurable amount and having a coefficient of friction substantially lower than the outer surface of said workpiece prior subjection to said method;
a second layer adjacent said outer layer being substantially nonporous and a third interior from and adjacent to said second layer, and having a substantial amount of diffused nitrogen therein.
6. The method of Claim 1 wherein said first preferred period of time is of an order of magnitude corresponding to about one to five hours and said second preferred period of time corresponds to an order of magnitude in the range of one-half to one and one half hours, and whereby each treated workpiece has an outer layer that has oxide portions substantially uniformly distributed therein and is substantially porous and operable to hold petroleum product in measurable amounts and having a coefficient of friction substantially lower than the outer surface of said workpiece prior subjection to said method;
a second layer adjacent said outer layer being substantially nonporous and a third layer interior from and adjacent to said second layer, and having a substantial amount of diffused nitrogen therein; and said outer layer having a thickness of an order of magnitude of five ten thousandths of an inch; said second layer having a thickness of an order of magnitude of one and one-half thousandths of an inch; and said third layer having thickness of an order of magnitude of six thousandths of an inch.
7. The method of Claim 1 wherein said first preferred period of time is of an order of magnitude corresponding to about one to five hours and said second preferred period of time corresponds to an order of magnitude in the range of one-half to one and one half hours, and whereby each treated workpiece has an outer layer that has oxide portions substantially uniformly distributed therein and is substantially porous and operable to hold petroleum product in measurable amounts and having a coefficient of friction substantially lower than the outer surface of said workpiece prior subjection to said method;
a second layer adjacent said outer layer being substantially nonporous, and a third layer interior from an adjacent to said second layer, and having a substantial amount of diffused nitrogen throughout therein; and the surface of said outer layer having a substantially greater hardness as measured by Rockwell test than the surface of said workpiece prior to subjection to said method.
8. In apparatus for heat treating metal workpieces, the improvements comprising:
a fluidizable sand bed furnace;
means holding metal workpieces within the sand of said furnace;
means conducting gas through said sand and said workpieces;
a source of gas flow;
means for humidifying said gas flow; and means transmitting said humidified gas flow to said conducting means.
9. In the apparatus of claim 8, said gas flow being nitrogen flow, and said humidifying means operable to humidify said gas flow with 10 per cent to 20 percent moisture, and said metal workpieces being made of ferrous metal.
10. In the method of claim 1 the improvements comprising:
said first temperature being substantially above 300 degrees Fahrenheit;
said workpieces having a mass on the order of magnitude exceeding one quarter ton, when said furnace has an interior diameter of the order of magnitude of 20 inches and a depth of the order of magnitude of 48 inches;
said first preferred atmosphere comprising a total flow exceeding the order of magnitude of 1200 cubic feet per hour;
said first preferred atmosphere comprising ammonia flowing at an order of magnitude corresponding to 700 cubic feet per hour;
said first preferred atmosphere comprising nitrogen flowing at an order of magnitude corresponding to 250 cubic feet per hour.
11. In the method of Claim 1, the improvements comprising:
said first temperature being measurably below 1000 degrees Fahrenheit and substantially above 900 degrees Fahrenheit;
said workpieces having a mass on the order of magnitude exceeding one quarter ton, when said furnace has an interior diameter of the order of magnitude of 20 inches and a depth of the order of magnitude of 48 inches;
said first preferred atmosphere comprising a total flow exceeding the order of magnitude of 1200 cubic feet per hour;
said first preferred atmosphere comprising ammonia flowing at an order of magnitude corresponding to 700 cubic feet per hour;
said first preferred atmosphere comprising nitrogen flowing at an order of magnitude corresponding to 250 cubic feet per hour;
said first preferred atmosphere comprising natural gas flowing at an order of magnitude corresponding to 350 cubic feet per hour;
passing nitrogen through a humidifier in such a manner as to obtain a resultant mixture of nitrogen humidified in the range of 10 percent to 20 percent;
said second preferred atmosphere comprising said humidified nitrogen mixture being introduced into said furnace at a rate having an order of magnitude of 300 cubic feet per hour;
and maintaining said second preferred atmosphere in said furnace with said mass of workpieces for a second preferred period of time;
said first period of time having an order of magnitude of 3 hours;
said second period of time having an order of magnitude in the range of one hour to one and one half hours.
12. In a heat treating method for case hardening metal workpieces utilizing gaseous entities flowing through a fluidized sand bed at temperatures substantially above the boiling point of moisture and substantially below the freezing point of the metal workpieces, the improvements comprising:
heating a fluidizable sand bed furnace to a first temperature, said first temperature being measurably below 1000 degrees Fahrenheit and substantially above 900 degrees Fahrenheit;
introducing workpieces into said furnace;
allowing the combined mass of the workpieces and the furnace to recover to said first temperature;
said workpieces having a mass on the order of magnitude exceeding one quarter ton, when said furnace has an interior diameter of the order of magnitude of 20 inches and a depth of the order of magnitude of 48 inches;
after said temperature recovery, introducing a first preferred atmosphere into said furnace;
said first preferred atmosphere comprising a total flow exceeding the order of magnitude of 1200 cubic feet per hour;
said first preferred atmosphere comprising ammonia flowing at an order of magnitude corresponding to 700 cubic feet per hour;
said first preferred atmosphere comprising nitrogen flowing at an order of magnitude corresponding to 250 cubic feet per hour;
said first preferred atmosphere comprising natural gas flowing at an order of magnitude corresponding to 350 cubic feet per hour;
maintaining said first preferred atmosphere in said furnace at said first temperature with said mass of workpieces for a first preferred period of time;
passing nitrogen through a humidifier in such a manner as to obtain a resultant mixture of nitrogen humidified in the range of 10 percent to 20 percent;
replacing said first preferred atmosphere with a second preferred atmosphere;
said second preferred atmosphere comprising said humidified nitrogen mixture being introduced into said furnace at a rate having an order of magnitude of 300 cubic feet per hour; and maintaining said second preferred atmosphere in said furnace with said mass of workpieces for a second preferred period of time.
13. A method for improving the wear characteristics and corrosion resistance of the surface of a metal comprising the steps of:
A. case-hardening the surface of pieces of the metal, the case hardening step comprising:
1. immersing the metal pieces in a fluidized bed of particulate material at a temperature between about 750 and about 1200°F;
2. introducing a first gaseous atmosphere into the bed, the first gaseous atmosphere selected from the group consisting of ammonia, nitrogen and natural gas while maintaining the temperature between about 750 and about 1200°F;
3. maintaining the metal pieces in contact with the first gaseous atmosphere for a time period between about 1 and about 5 hours;
4. contacting the metal pieces with a second gaseous atmosphere containing nitrogen and water while said pieces are immersed in a fluidized bed of particulate material at a temperature between about 750 and about 1200°F; and
5. maintaining the metal piece in contact with the second gaseous atmosphere for a time period between about 30 minutes and about 90 minutes; and B. subsequent to the case-hardening step, contacting the case-hardened metal piece with a coating composition.
C. allowing the coating composition retained on the metal piece to cure.
C. allowing the coating composition retained on the metal piece to cure.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US64656484A | 1984-09-04 | 1984-09-04 | |
| US646,564 | 1984-09-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1258609A true CA1258609A (en) | 1989-08-22 |
Family
ID=24593539
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000489938A Expired CA1258609A (en) | 1984-09-04 | 1985-09-03 | Shallow case hardening process |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0192745A1 (en) |
| AU (1) | AU4780085A (en) |
| CA (1) | CA1258609A (en) |
| WO (1) | WO1986001541A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3718240C1 (en) * | 1987-05-30 | 1988-01-14 | Ewald Schwing | Process for the heat treatment of metallic workpieces in a gas-flowed fluidized bed |
| US5316594A (en) * | 1990-01-18 | 1994-05-31 | Fike Corporation | Process for surface hardening of refractory metal workpieces |
| JP4977700B2 (en) * | 2005-07-21 | 2012-07-18 | ハード テクノロジーズ プロプライエタリー リミテッド | Composite surface treatment of metal objects |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1600086A (en) * | 1968-12-30 | 1970-07-20 | ||
| US4249889A (en) * | 1979-06-05 | 1981-02-10 | Kemp Willard E | Method and apparatus for preheating, positioning and holding objects |
| US4410373A (en) * | 1981-09-30 | 1983-10-18 | Kemp Willard E | Process for heat treatment of a metal workpiece |
-
1985
- 1985-09-03 CA CA000489938A patent/CA1258609A/en not_active Expired
- 1985-09-04 AU AU47800/85A patent/AU4780085A/en not_active Abandoned
- 1985-09-04 WO PCT/US1985/001687 patent/WO1986001541A1/en unknown
- 1985-09-04 EP EP19850904552 patent/EP0192745A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| AU4780085A (en) | 1986-03-24 |
| EP0192745A1 (en) | 1986-09-03 |
| WO1986001541A1 (en) | 1986-03-13 |
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