US1747549A - Hardening process - Google Patents
Hardening process Download PDFInfo
- Publication number
- US1747549A US1747549A US288816A US28881628A US1747549A US 1747549 A US1747549 A US 1747549A US 288816 A US288816 A US 288816A US 28881628 A US28881628 A US 28881628A US 1747549 A US1747549 A US 1747549A
- Authority
- US
- United States
- Prior art keywords
- case
- nitrification
- cyanide
- hardness
- hardening
- 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
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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
- C23C8/40—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 liquids, e.g. salt baths, liquid suspensions
- C23C8/42—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 liquids, e.g. salt baths, liquid suspensions only one element being applied
- C23C8/48—Nitriding
- C23C8/50—Nitriding of ferrous surfaces
Definitions
- My invention provides a new means and process for producing a harder, tougher and more ductile nitrification case upon a ferrous object in a much shorter period of time.
- I provide a molten nitrification bath as distinguished from the prior art which provided the nitrogen from a gaseous atmosphere.
- I provide preferably a molten bath of the mixed cyanides of sodium and potassium, having such a composition that a low melting point is obtained.
- I then immerse the object to be case hardened within the molten mixed cyanides, being careful to keep the temperature (below 580 C.
- the case hardening proceeds rapidly and in about 2 hours may produce a hardened nitride case having a thickness of about 0.001 inches. 7
- the resulting case obtained by the process of my invention is substantially harder than thecase obtained by the prior nitrification process, and is also more ductile.
- cyanide other substances than cyanide may be used, such for lnstance, as a nnxture of aconvement cyanide and a' cyanamide.
- salts which produce the "desired reduction in melting point may be used althoughit is preferable'that substances which evolve-oxygen be excluded.
- the process of my invention is particularly applicable'to alloy steels,- such'as those -con-' 'taining vanadium or aluminum, as well as such elements as manganese, silicon and chromium, and such alloy steels are the preferred materials for treatmentby my process.
- alloy steels such'as those -con-' 'taining vanadium or aluminum, as well as such elements as manganese, silicon and chromium, and such alloy steels are the preferred materials for treatmentby my process.
- alloys containing the vanadium and aluminum produce cases having a maximum hardness and may be made sufiiciently hard to scratch glass readily.
- the alloys containing ,manganese; silicon and chromium, also produce a substantial degree of hardness al-v though less than the first two mentioned a1- loying elements when treated by the process of my invention. In each case however, a
- the hardness obtained by the process of my invention is conveniently indicated by measurements, in terms of microcharacter units, as made upon a suitable steel. Comparison was madebetween the hardness obtained by the previously used gaseous ammonia nitrification process, and by the process of my invention, upon four typical steelshaving the Samples of .the same alumimicrocharacte'r units.
- case-hardeningferrous I articles 7 which comprises treating an article having a surface contalnmg vanadium and of a composition adapting it for nitride casing with a liquid cyanide at a temperature between 445" (land 600 C.
Description
20 from 24 hours to 90 hours.
Patented Feb. 18, 1930 UNITED STATES PATENT OFFICE AUGUSTUS B. KINZEL, F BAYSIDE, YORK, ASSIGNOItTO ELECTED METALLURGI- CAL ., A CORPORATION or wns'r vmeinm nannnmne rnocnss a hard nitrification case in a minimum length of time, and for another, the provision of a new nitrification case hardening process, and a new material for the operation thereof.
It has been found that by the diffusion I of active nitrogen at relatively low temperatures into and through a surface layer of a ferrous material object having certain alloy constituents, a hard and durable case or surface layer is obtained. This processis desirably carried out at temperatures below.
about 600 C., and is customarily done by heatingthe metal part'to theappropriate temperature in an atmosphere of gaseous ammonia, over a period of time, ranging My invention provides a new means and process for producing a harder, tougher and more ductile nitrification case upon a ferrous object in a much shorter period of time.
In practicing my .invention I provide a molten nitrification bath as distinguished from the prior art which provided the nitrogen from a gaseous atmosphere. I provide preferably a molten bath of the mixed cyanides of sodium and potassium, having such a composition that a low melting point is obtained. I then immerse the object to be case hardened within the molten mixed cyanides, being careful to keep the temperature (below 580 C. The case hardening proceeds rapidly and in about 2 hours may produce a hardened nitride case having a thickness of about 0.001 inches. 7
It may be noted that this is a broadly dif- 40 ferent process'from prior methods of case hardening with cyanide baths in which a temperature well above 700 (1., is always reached, and a carburization case only is produced. In the process of my invention no carburization occurs at the low'tem'peraturebut only a nitrification. f
The resulting case obtained by the process of my invention is substantially harder than thecase obtained by the prior nitrification process, and is also more ductile. When pro- 1928. Serial No. 288,816.
duced upon a given suitable alloy, it has a hardness about four times as great as that produced by the previous nitrification process upon the same alloy, and it is also sufficiently ductile to permit'of considerable distortion, since pressure by a point or small ball upon the treated object does not crack or shatter the case hardened coating as occurs with. nitrification cases produced by the methods of the prior art, which are'much less resistant to deformation and pressure.
In the preparation of thecase hardening bath of my invention, I find it convenient to provide a mixture of about 58% of sodium 7 cyanide and about 47% of potassium cyanide, this mixture producing the eutectic, or lowestmelting composition and fusing at about 445 C. This bath is thus fluid over a convenient temperature range below the criticalpoint at 580 C.,"at which transformation of the nitrification product begins to occur. By the process as above described I am thus enabled to treat a ferrous object for case hardening to obtain a newand useful product with a saving of time, and cost. The process is particularly advantageous because of the low temperature at which it operates whereby the object may be given suitable heat treatments for the production of desired physical characteristics and may thereafter be case hardened without change in the characteristics of the body or danger of deformation or internal strains.
ing of maximum hardness is obtained without the necessity for any subsequent heat treating steps to temper the case.
As abath for the operation of the process Likewise a casof my invention I have, above, disclosed a mixture of sodium and potassium cyanide. It is not however, necessary that such a mixture be used since-there are various other mixtures which obtain a similar result. For instance, mixtures of other cyanides such as sodium cyanide and zinc cyanide, or potassium cypoints sufliciently low to bev useable for the amide. and magnesium cyanidewr vice versa,, produce eutect c mlxtures havmg meltlng' process of my invention. Alternatively,"
other substances than cyanide may be used, such for lnstance, as a nnxture of aconvement cyanide and a' cyanamide. Likewise other salts which produce the "desired reduction in melting point may be used althoughit is preferable'that substances which evolve-oxygen be excluded. I
The process of my invention is particularly applicable'to alloy steels,- such'as those -con-' 'taining vanadium or aluminum, as well as such elements as manganese, silicon and chromium, and such alloy steels are the preferred materials for treatmentby my process. The
alloys containing the vanadium and aluminum produce cases having a maximum hardness and may be made sufiiciently hard to scratch glass readily. The alloys containing ,manganese; silicon and chromium, also produce a substantial degree of hardness al-v though less than the first two mentioned a1- loying elements when treated by the process of my invention. In each case however, a
v substantial gain in hardness and ductility appears over 'a nitrified case made according to p the prior art.
The hardness obtained by the process of my invention is conveniently indicated by measurements, in terms of microcharacter units, as made upon a suitable steel. Comparison was madebetween the hardness obtained by the previously used gaseous ammonia nitrification process, and by the process of my invention, upon four typical steelshaving the Samples of .the same alumimicrocharacte'r units.
steels-treated in the bath of my invention gave surface hardness values varying from 600,000 to 800,000 microcharacter units.
' By the process of my invention I have thus produced a new and simple means of obtaining a case hardenedsurface upon ferrous objects, which is much sim ler to operate, and
much more rapid and e ective than the previous methods.'
While I have described several embodiments of the process of my invention it is capable of still other embodiments, adaptations and modifications without departure from the spirit thereof and I desire therefore that only f1,747,54'e I nitride casing, with a liquid non-oxidizing nitrogen-containing salt at a temperature below 600 C.
2. The process of case-hardening ferrous articles which comprises treating an article having a surface composition adapting it for nitride casing with a liquid cyanide at a temperature below 600 C.
3. The process of case-hardeningferrous I articles 7 which comprises treating an article having a surface contalnmg vanadium and of a composition adapting it for nitride casing with a liquid cyanide at a temperature between 445" (land 600 C.
In testimony whereof, I aflix my signature.
AUGUSTUS B. KINZEL.
- such limitations shall be imposed upon the 1 appended claims as are indicated therein, or required by the prior art.
I claim as my invention:
.1 The process of case-hardening ferrous articles which comprises treating an article having a surface composition adapting it for
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US288816A US1747549A (en) | 1928-06-27 | 1928-06-27 | Hardening process |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US288816A US1747549A (en) | 1928-06-27 | 1928-06-27 | Hardening process |
Publications (1)
Publication Number | Publication Date |
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US1747549A true US1747549A (en) | 1930-02-18 |
Family
ID=23108757
Family Applications (1)
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US288816A Expired - Lifetime US1747549A (en) | 1928-06-27 | 1928-06-27 | Hardening process |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1260920B (en) * | 1962-06-18 | 1968-02-08 | Shinzoh Satoh | Process for hardening iron or steel electroplated with titanium |
-
1928
- 1928-06-27 US US288816A patent/US1747549A/en not_active Expired - Lifetime
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1260920B (en) * | 1962-06-18 | 1968-02-08 | Shinzoh Satoh | Process for hardening iron or steel electroplated with titanium |
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