US3158514A - Carbonitriding process - Google Patents
Carbonitriding process Download PDFInfo
- Publication number
- US3158514A US3158514A US186377A US18637762A US3158514A US 3158514 A US3158514 A US 3158514A US 186377 A US186377 A US 186377A US 18637762 A US18637762 A US 18637762A US 3158514 A US3158514 A US 3158514A
- Authority
- US
- United States
- Prior art keywords
- carbonitriding
- temperature
- iron
- nodular iron
- metal
- 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 - Lifetime
Links
Images
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
- C23C8/28—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases more than one element being applied in one step
- C23C8/30—Carbo-nitriding
- C23C8/32—Carbo-nitriding of ferrous surfaces
Definitions
- This invention relates to a process for heat treating ferrous products and more particularly to a process for carbonitriding nodular iron and gray iron.
- Carbonitriding is a process employed to produce an intensely hard case upon ferrous objects and involves essentially the exposure of such a ferrous article to a temperature of at least 1000 F. in an atmosphere containing carburizing gas and a source of combined nitrogen such as ammonia.
- a very clear description of this process in detail is contained in the American Society for Metals Handbook, 1948 edition, at pages 696-697.
- This invention is especially directed to a process for applying this carbonitriding process to articles formed of nodular iron or gray iron whereby a hard surface is produced over a core which also has the maximum possible hardness.
- a typical nodular iron composition suitable for the practice of this invention is tabulated below:
- This invention is also applicable to any conventional gray iron composition.
- This drawing is a graphical representation of hardness obtained in nodular iron specimens when quenched from an austenitizing temperature after having been held for varying lengths of time at supercritical temperatures.
- the gray iron or nodular iron object is heated sufliciently high to completely austenitize the object. It is then cooled to a temperature just above 1500 F. and exposed at this temperature to a carbonitriding atmosphere. The object is then quenched and, if necessary, tempered to the desired value.
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Description
Nov. 24, 1964 J. B. SAXTON 3,153,514
CARBONITRIDING PROCESS Filed April 10, 1962 60 DIRECT OUENCHED FROM I650F //v /0 4/100500:
f NACL sou/flog; m/zmq/Z/Z/m z/z/lz/jzfl/jjzz/jm/ jg;
T T WI/50F 1 \l 4 30 9: I 20 3 E Q i /0 E t U a m 3 Q 0 HOURS HELD AT /ND/CA TED TEMPERATURES AFTER 545T COOL ING FROM AUS TEN/T/Z/NG TEMPERATURE OF I650? JOHN B. SAX TON INVENTOR ATTORN EYS United States Patent 3,158,514 CARBGNII'EGDING PRSCESS John B. Sexton, Detroit, Mich, assignor to Ford Motor Company, Dearhorn, Mich, a corporation oi Delaware Filed Apr. 10, 1962, Ser. No. 186,377 1 Ciairn. (Cl. 148-165) This invention relates to a process for heat treating ferrous products and more particularly to a process for carbonitriding nodular iron and gray iron. Carbonitriding is a process employed to produce an intensely hard case upon ferrous objects and involves essentially the exposure of such a ferrous article to a temperature of at least 1000 F. in an atmosphere containing carburizing gas and a source of combined nitrogen such as ammonia. A very clear description of this process in detail is contained in the American Society for Metals Handbook, 1948 edition, at pages 696-697.
This invention is especially directed to a process for applying this carbonitriding process to articles formed of nodular iron or gray iron whereby a hard surface is produced over a core which also has the maximum possible hardness. A typical nodular iron composition suitable for the practice of this invention is tabulated below:
This invention is also applicable to any conventional gray iron composition.
To aid in understanding this invention, a single figure of drawing has been presented. This drawing is a graphical representation of hardness obtained in nodular iron specimens when quenched from an austenitizing temperature after having been held for varying lengths of time at supercritical temperatures.
The data depicted by this drawing was obtained by fully austenitizing identical samples of nodular iron and bringing these samples to a uniform temperature of 1650 F. One sample was cooled to 1550 F. and held for four hours and quenched. A second sample was cooled to 1500" F., held for four hours and quenched. A third sample was similarly treated at 1450 F. This drawing demonstrates that at quenching temperatures at least as high as 1500" F. there is obtained essentially the same hardness as that obtained from a quenching temperature of 1650 F. Contrariwise, the specimen permitted to remain at 1450 F. gave a decidedly inferior hardness.
This inferior hardness is due to the premature and unwanted decomposition of austenite into the soft constituent ferrite at 1450 F.
This work clearly indicated a course to be taken to enable a nodular iron or gray iron object to be carbonitrided and simultaneously maintain a veryhard center. Carbonitriding at very high temperatures is impractical because of the very rapid thermal decomposition of the nitrogenous portions of the carbonitriding gas. Carbonitriding of nodular iron or gray iron substantially below 1500" F. produces inferior results by virtue of the premature decomposition of austenite into ferrite. These facts determine that a suitable carbonitriding range is just above 1500 F. and below the temperatures at which very rapid decomposition of the nitrogen compounds in the carbonitriding atmosphere takes place.
Accordingly, to accomplish such carbonitriding, the gray iron or nodular iron object is heated sufliciently high to completely austenitize the object. It is then cooled to a temperature just above 1500 F. and exposed at this temperature to a carbonitriding atmosphere. The object is then quenched and, if necessary, tempered to the desired value.
I claim as my invention:
A process for carbonitriding a metal chosen from the group consisting of nodular iron and gray iron comprising completely austenitizing the metal, cooling the austenitized metal from the austenitizing temperature to a selected temperature which selected temperature is high enough to insure substantially complete stability of the austenitic structure during the carbonitriding cycle, which selected temperature is low enough to insure substantial stability of the carbonitriding atmosphere and which selected temperature is not substantially lower than 1500" F., carbonitriding the metal at the selected temperature to produce a very hard case, and quenching the carbonitrided metal to produce a hard core.
References Cited in the file of this patent UNITED STATES PATENTS 946,360 Hodgkinson Ian. 11, 1910 1,065,697 Machlet June 24, 1913 1,092,925 Machlet Apr. 14, 1914 1,748,623 Sergeson Feb. 25, 1930 2,025,134 Stammberger Dec. 24, 1935 2,151,190 Cowan Mar. 21, 1939 2,188,226 Machlet Jan. 23, 1940 2,472,320 Vennerholm June 7, 1949 FOREIGN PATENTS 696,688 Great Britain Sept. 9, 1953 OTHER REFERENCES W. H. Holcroft: Carbonitriding in Present Practice," Metal Progress, vol. 58, No. 6, December 1950, pp. 843- 846.
G. W. Rengstorif et al.: The Carbonitriding Process of Case Hardening Steel, ASM preprint, 1950, No. 1, 27 pp.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US186377A US3158514A (en) | 1962-04-10 | 1962-04-10 | Carbonitriding process |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US186377A US3158514A (en) | 1962-04-10 | 1962-04-10 | Carbonitriding process |
Publications (1)
Publication Number | Publication Date |
---|---|
US3158514A true US3158514A (en) | 1964-11-24 |
Family
ID=22684708
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US186377A Expired - Lifetime US3158514A (en) | 1962-04-10 | 1962-04-10 | Carbonitriding process |
Country Status (1)
Country | Link |
---|---|
US (1) | US3158514A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3895923A (en) * | 1969-12-30 | 1975-07-22 | Texas Instruments Inc | High strength metal carbonitrided composite article |
US4776901A (en) * | 1987-03-30 | 1988-10-11 | Teledyne Industries, Inc. | Nitrocarburizing and nitriding process for hardening ferrous surfaces |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US946360A (en) * | 1907-08-29 | 1910-01-11 | William Richard Hodgkinson | Treatment of iron or steel. |
US1065697A (en) * | 1906-05-25 | 1913-06-24 | Adolph W Machlet | Annealing process, &c. |
US1092925A (en) * | 1907-07-12 | 1914-04-14 | Adolph W Machlet | Hardening or treatment of steel, iron, &c. |
US1748623A (en) * | 1929-03-28 | 1930-02-25 | Central Alloy Steel Corp | Method of nitriding steel articles |
US2025134A (en) * | 1932-03-15 | 1935-12-24 | Leeds & Northrup Co | Program control of nitriding |
US2151190A (en) * | 1938-12-31 | 1939-03-21 | Surface Combustion Corp | Method of producing a composite carbide and nitride case on steel articles |
US2188226A (en) * | 1938-02-24 | 1940-01-23 | Adolph W Machlet | Method of casing ferrous articles |
US2472320A (en) * | 1941-02-05 | 1949-06-07 | Ford Motor Co | Method of heat-treating steel |
GB696688A (en) * | 1949-11-16 | 1953-09-09 | Renault | Improved method for surface hardening by carbonitriding at low temperatures |
-
1962
- 1962-04-10 US US186377A patent/US3158514A/en not_active Expired - Lifetime
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1065697A (en) * | 1906-05-25 | 1913-06-24 | Adolph W Machlet | Annealing process, &c. |
US1092925A (en) * | 1907-07-12 | 1914-04-14 | Adolph W Machlet | Hardening or treatment of steel, iron, &c. |
US946360A (en) * | 1907-08-29 | 1910-01-11 | William Richard Hodgkinson | Treatment of iron or steel. |
US1748623A (en) * | 1929-03-28 | 1930-02-25 | Central Alloy Steel Corp | Method of nitriding steel articles |
US2025134A (en) * | 1932-03-15 | 1935-12-24 | Leeds & Northrup Co | Program control of nitriding |
US2188226A (en) * | 1938-02-24 | 1940-01-23 | Adolph W Machlet | Method of casing ferrous articles |
US2151190A (en) * | 1938-12-31 | 1939-03-21 | Surface Combustion Corp | Method of producing a composite carbide and nitride case on steel articles |
US2472320A (en) * | 1941-02-05 | 1949-06-07 | Ford Motor Co | Method of heat-treating steel |
GB696688A (en) * | 1949-11-16 | 1953-09-09 | Renault | Improved method for surface hardening by carbonitriding at low temperatures |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3895923A (en) * | 1969-12-30 | 1975-07-22 | Texas Instruments Inc | High strength metal carbonitrided composite article |
US4776901A (en) * | 1987-03-30 | 1988-10-11 | Teledyne Industries, Inc. | Nitrocarburizing and nitriding process for hardening ferrous surfaces |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US3117041A (en) | Heat treated steel article | |
US4202710A (en) | Carburization of ferrous alloys | |
US3870572A (en) | Process for nitriding unalloyed or low-alloy steel | |
US3337376A (en) | Method of hardening hypereutectoid steels | |
US3131097A (en) | Heat treatment of bearing steel to eliminate retained austenite | |
ATE16118T1 (en) | PROCESS FOR HEAT TREATMENT OF METAL WORKPIECES BY CARBURIZING. | |
US3158514A (en) | Carbonitriding process | |
US3216869A (en) | Method of heat treating steel | |
US2664369A (en) | Method of softening low-carbon medium-alloy steel | |
US2458655A (en) | Process of case-hardening metals | |
US3826694A (en) | Thermal treatment of steel | |
US1961520A (en) | Method of case hardening steel | |
US3513038A (en) | Method for producing fragmenting steel | |
US20140216608A1 (en) | Method for cooling metal parts having undergone a nitriding/nitrocarburising treatment in a molten salt bath, unit for implementing said method and the treated metal parts | |
GB1034157A (en) | Case hardening ferrous articles | |
US3795551A (en) | Case hardening steel | |
US3892597A (en) | Method of nitriding | |
US2779698A (en) | Method of improving machinability of steel | |
US2563672A (en) | Machinability of quench-hardened alloy steels containing retained austenite | |
GB851346A (en) | Process of nitriding hardenable steel | |
US3526552A (en) | Metal treating | |
US3009843A (en) | Steel products and method for producing same | |
US2426773A (en) | Tempering process for steel objects | |
US1808355A (en) | Method of nitrification | |
US2829996A (en) | Process for improving the machining qualities of steel |