US2057274A - Process for heat treating ferrous metals - Google Patents
Process for heat treating ferrous metals Download PDFInfo
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- US2057274A US2057274A US671303A US67130333A US2057274A US 2057274 A US2057274 A US 2057274A US 671303 A US671303 A US 671303A US 67130333 A US67130333 A US 67130333A US 2057274 A US2057274 A US 2057274A
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- Prior art keywords
- metal
- hydrogen
- nitrogen
- treated
- ferrous metals
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- 229910052751 metal Inorganic materials 0.000 title description 47
- 239000002184 metal Substances 0.000 title description 47
- 238000000034 method Methods 0.000 title description 18
- 230000008569 process Effects 0.000 title description 12
- -1 ferrous metals Chemical class 0.000 title description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 28
- 239000001257 hydrogen Substances 0.000 description 25
- 229910052739 hydrogen Inorganic materials 0.000 description 25
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 23
- 229910052757 nitrogen Inorganic materials 0.000 description 14
- 239000000243 solution Substances 0.000 description 13
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 11
- 239000001301 oxygen Substances 0.000 description 11
- 229910052760 oxygen Inorganic materials 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 238000005121 nitriding Methods 0.000 description 6
- 230000000704 physical effect Effects 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 5
- 229910017464 nitrogen compound Inorganic materials 0.000 description 5
- 150000002830 nitrogen compounds Chemical class 0.000 description 5
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 4
- 239000003792 electrolyte Substances 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 238000005868 electrolysis reaction Methods 0.000 description 3
- 239000000284 extract Substances 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 description 2
- AWJWCTOOIBYHON-UHFFFAOYSA-N furo[3,4-b]pyrazine-5,7-dione Chemical compound C1=CN=C2C(=O)OC(=O)C2=N1 AWJWCTOOIBYHON-UHFFFAOYSA-N 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 230000000149 penetrating effect Effects 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 241001579016 Nanoa Species 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 238000007550 Rockwell hardness test Methods 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- KXZJHVJKXJLBKO-UHFFFAOYSA-N chembl1408157 Chemical compound N=1C2=CC=CC=C2C(C(=O)O)=CC=1C1=CC=C(O)C=C1 KXZJHVJKXJLBKO-UHFFFAOYSA-N 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 150000001913 cyanates Chemical class 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 150000002826 nitrites Chemical class 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 239000012286 potassium permanganate Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- 239000004317 sodium nitrate Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
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
- C23C8/40—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
- the principal object of the present invention is to provide for controllably changing the physical properties hardness, tensile strength and ductility-of the metal, and thereby, in some 5 cases, as with structural steel, obtaining greater duty with the same weight or the same duty with less weight, and in other cases increasing the hardness and structural strength as in rails, gears, tools and the like.
- the invention consists in treating ferrous metal by contacting it while hot with a water solution containing nitrogen compounds, and liberating both nitrogen and hydrogen of combination in the water from the solution at the surface of the metal, the hydrogen operating to deeply penetrate the metal with the admixture of hydrogen and nitrogen imparting hardness and brittleness to the metal, and then applying oxygen at the surface of the metal which by combination with the occluded hydrogen extracts it and tempers the brittleness and restores ductility to the metal.
- the invention also comprises the improvements to be presently described and finally claimed.
- Figure 1 is a diagrammatic or schematic view principally in section and illustrative of apparatus for a galvanic action of a local character.
- Fig. 2 is a similar view illustrative of apparatus for a short circuited galvanic action
- Fig. 3 is a similar view illustrative of a galvanic action in connection with applied current.
- ferrous metals treated by the present invention to change their hardness and tensile strength, ductility and other physical properties are ferrous metals and ferrous alloys which can withstand sudden changes of temperature encountered in the treatment.
- the invention is practiced, (l) by immersion of the heated metal at temperatures varying from 1000 degrees Fahrenheit to 2200 degrees Fahrenheit more or less in, or by passing it through a stream or a jet, or streams or jets, of an 5e aqueous solution containing nitrogen, such as cyanicles, cyanates, nitrates, nitrites of sodium, potassium, calcium and the like and ammoniacai compounds, amines and the like.
- These variant temperatures are one method of control of the changes in hardness, tensile strength, ductility and physical properties.
- the temperature of the solution used varies from 40 degrees Fahrenheit to 100 degrees Fahrenheit more or less, this variation in temperature being another method of control, and the period of immersion or its 5 equivalent in passing through the streams or jets is another method of control.
- this first step is to utilize the hydrogen released from the aqueous solution as a carrier for deeply nitriding the metal, whereby 10 it is made hard and brittle, but the brittleness is reduced with consequent restoration of duetility by the second step to be presently described.
- the invention is also practiced and completed, (2) by immersion into, or passage through 15 streams or jets of aqueous solutions containing chemically combined oxygen, such as potassium permanganate (KMnOr) sodium nitrate (NaNOa), and chromic acid (HZCIOi), using the controls given in the preceding paragraph.
- chemically combined oxygen such as potassium permanganate (KMnOr) sodium nitrate (NaNOa), and chromic acid (HZCIOi)
- the oxygen liberated combines with the hydrogen 29 occluded in the metal and reduces the brittleness leaving the nitrogen inclusion in the metal.
- I may superimpose on the heated metal being so treated, an external, direct electro-motive force, of varying value of current density or fre- 35 quency.
- an external, direct electro-motive force of varying value of current density or fre- 35 quency.
- I found that the reversal of polarity and the varying voltage and current density were other methods of con trol of the hardness, tensile strength, ductility and physical properties.
- one example of an increase in hardness and physical properties was as follows: A standard .505 inch tensile specimen (carbon 0.26) heated to 1800 degrees Fahrenheit was immersed for five seconds in a solution of sodium cyanide (NaCNl of a strength of one pound of cyanide to one gallon of water, and immediately removed from this solution and immersed into a concentrated solution of chromic acid H. .CrO and allowed to cool therein. (The temperature of bothsolutions was about fifty degrees Fahrenheit.) The untreated specimen had an average hardness on the Rockwell B scale of and this was increased to 46 on the C scale for the treated specimen. The tensile strength was increased from 59,500 pounds per square inch to 187,800 pounds per square inch.
- Armco iron being a practically pure iron, as rolled by the American Rolling Mill Company
- the ultimate tensile strength from 42,000 pounds per square inch to 58,000 to '78,500 pounds per square inch by one or the other of the processes as outlined above.
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- 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
Oct. 13,1936. w N M YHEW 2,051,274
PROCESS FOR HEAT TREATING FERROUS METALS Filed May 16, 1953 awn m nun 55$: %ZZQC M15077 Ma I561).
' a) I 7 V Patented Oct. 13, 1936 UNITED STATES PATENT OFFICE PROCESS FOR HEAT TREATING FERROUS METALS Claims.
The principal object of the present invention is to provide for controllably changing the physical properties hardness, tensile strength and ductility-of the metal, and thereby, in some 5 cases, as with structural steel, obtaining greater duty with the same weight or the same duty with less weight, and in other cases increasing the hardness and structural strength as in rails, gears, tools and the like.
' Other objects of the present invention will appear from the following description at the end of which the invention will be claimed.
Generally stated the invention consists in treating ferrous metal by contacting it while hot with a water solution containing nitrogen compounds, and liberating both nitrogen and hydrogen of combination in the water from the solution at the surface of the metal, the hydrogen operating to deeply penetrate the metal with the admixture of hydrogen and nitrogen imparting hardness and brittleness to the metal, and then applying oxygen at the surface of the metal which by combination with the occluded hydrogen extracts it and tempers the brittleness and restores ductility to the metal.
The invention also comprises the improvements to be presently described and finally claimed.
To comply with the rules of the Patent Oflice,
a; drawing accompanies this specification, and in Figure 1 is a diagrammatic or schematic view principally in section and illustrative of apparatus for a galvanic action of a local character.
Fig. 2 is a similar view illustrative of apparatus for a short circuited galvanic action, and
Fig. 3 is a similar view illustrative of a galvanic action in connection with applied current.
Examples of ferrous metals treated by the present invention to change their hardness and tensile strength, ductility and other physical properties are ferrous metals and ferrous alloys which can withstand sudden changes of temperature encountered in the treatment.
The invention is practiced, (l) by immersion of the heated metal at temperatures varying from 1000 degrees Fahrenheit to 2200 degrees Fahrenheit more or less in, or by passing it through a stream or a jet, or streams or jets, of an 5e aqueous solution containing nitrogen, such as cyanicles, cyanates, nitrates, nitrites of sodium, potassium, calcium and the like and ammoniacai compounds, amines and the like. These variant temperatures are one method of control of the changes in hardness, tensile strength, ductility and physical properties. The temperature of the solution used varies from 40 degrees Fahrenheit to 100 degrees Fahrenheit more or less, this variation in temperature being another method of control, and the period of immersion or its 5 equivalent in passing through the streams or jets is another method of control.
The purpose of this first step is to utilize the hydrogen released from the aqueous solution as a carrier for deeply nitriding the metal, whereby 10 it is made hard and brittle, but the brittleness is reduced with consequent restoration of duetility by the second step to be presently described.
The invention is also practiced and completed, (2) by immersion into, or passage through 15 streams or jets of aqueous solutions containing chemically combined oxygen, such as potassium permanganate (KMnOr) sodium nitrate (NaNOa), and chromic acid (HZCIOi), using the controls given in the preceding paragraph. The oxygen liberated combines with the hydrogen 29 occluded in the metal and reduces the brittleness leaving the nitrogen inclusion in the metal.
By immersing the heated metal into any of the above or similar compounds or electrolytes, use is made of the electro-motive force generated to 25 release nitrogen, hydrogen, or oxygen or other, gas, either by localized or internal currents, or produced by short circuiting the metal to be treated with the container of the electrolyte, thus providing a method of control for the physical 30 properties, hardness, tensile strength and ductility of the metal.
I may superimpose on the heated metal being so treated, an external, direct electro-motive force, of varying value of current density or fre- 35 quency. With the specimen so treated with direct current, as outlined above, I found that the reversal of polarity and the varying voltage and current density were other methods of con trol of the hardness, tensile strength, ductility and physical properties. By making the metal the anode hydrogen is disassociated at its surface and induces deep nitriding and by making the metal the cathode oxygen is disassociated at its surface and by combination removes hydrogen. 45 In this paragraph reference is made to the two step process consisting of deeply nitriding in the presence of hydrogen and removing occluded hydrogen by the application of oxygen.
By means of the above processes I have increased the Rockwell hardness of 0.25% carbon steel from 60 to 67 on the B scale, for an untreated specimen, even up to from 45 to 52 on the 0 scale for 2. treated specimen.
I have also by the means outlined above increased the ultimate tensile strength of untreated metal, averaging from 59,000 to 60,000 pounds per square inch even up to 178.500 to 187,800 pounds per square inch with proportionate increase in the elastic limit. These ultimate tensile strength tests were made on a Riehle universal screwtesting machine.
By way of further description and not limitation, one example of an increase in hardness and physical properties was as follows: A standard .505 inch tensile specimen (carbon 0.26) heated to 1800 degrees Fahrenheit was immersed for five seconds in a solution of sodium cyanide (NaCNl of a strength of one pound of cyanide to one gallon of water, and immediately removed from this solution and immersed into a concentrated solution of chromic acid H. .CrO and allowed to cool therein. (The temperature of bothsolutions was about fifty degrees Fahrenheit.) The untreated specimen had an average hardness on the Rockwell B scale of and this was increased to 46 on the C scale for the treated specimen. The tensile strength was increased from 59,500 pounds per square inch to 187,800 pounds per square inch.
Upon examination of the micro-structure of the cross section of the treated specimen I found a gradient of dark areas from the center to the outside of the specimen difiering radically from a case, or case hardening, the darkest areas were at the outside and indicated a nitrogen and/or other occlusion or inclusion. This is borne out by Rockwell hardness tests which showed a gradient from a hard exterior to a softer interior having no sudden transition as is found in a case.
By varying one or other of the various controls, as outlined above, and only increasing the ultimate tensile strength to about 90,000 pounds per square inch, I have increased the ductility of the treated specimen about 10% greater than that of the untreated specimen. In this para graph reference is made to the two step process hereinabove defined and the controls effect the deepness of the penetration in the nitriding step and the removal of occluded hydrogen in the second step. The deeper the nitriding with hydrogen the greater the increase in tensile strength accompanied with hardness and brittleness and the greater the removal of hydrogen the greater the consequent recovery in ductility.
By methods above described I have hardened what is known as Armco iron (being a practically pure iron, as rolled by the American Rolling Mill Company) from 50 for the untreated specimen on the Rockwell 13" scale to for the treated specimen on the same scale, and have increased the ultimate tensile strength from 42,000 pounds per square inch to 58,000 to '78,500 pounds per square inch by one or the other of the processes as outlined above.
In Fig. l the E. M. F. is locally generated between the electrolyte I and metal 2. In Fig. 2 the metal 2. is short circuited with the container 3, and in Fig. 3 current is applied to the metal 2 and to the container 3 as indicated at 4.
Concentrated solutions or electrolytes may well be used, but the degree of concentration is another means of control of the physical properties of the treated metal.
It will be obvious to those skilled in the art to which the invention relates that modifications may be made in details of construction and arrangement and matters of mere form without departing from the spirit of the invention which is not limited to such matters, or otherwise than the prior art and the appended claims may require.
I claim:
1. The improvement in the process of treatin ferrous metals which consists in contacting the metal while hot with a water solution containing a nitrogen compound and deeply penetrating the metal by liberating in contact therewith nitrogen and hydrogen which carries the nitrogen deeply into the metal making the same brittle and hard, and extracting hydrogen leaving the nitrogen by liberating oxygen from a solution containing it in contact with the treated metal.
2. The process which consists of deeply impregnating ferrous metal with nitrogen which consists in simultaneously liberating nitrogen from an aqueous solution containing nitrogen compounds and hydrogen by electrolysis of the water of the solution in contact with the ferrous metal while hot, and extracting hydrogen from the metal by liberating oxygen from a solution containing it in contact with the treated metal.
3. In the process described in claim 2 the extraction of the hydrogen from the treated metal by making it the anode in the electrolysis thereby releasing oxygen from the aqueous solution which extracts hydrogen from the metal.
4. The process which consists in nitriding ferrous metal by the electrolysis of a water solution containing nitrogen compound thereby liberating nitrogen from the compound and hydrogen from the water in contact with the hot metal by an applied E. M. F. and subjecting the surface of the treated metal to contact with oxygen which extracts hydrogen from the treated metal by chemical combination with the hydrogen.
5. The improvement in the process of treating ferrous metals which consists in contacting the metal while at a temperature above one thousand degrees Fahrenheit with a solution containing a nitrogen compound and deeply penetrating the metal by liberating in contact therewith nitrogen and hydrogen which carries the nitrogen deeply into the metal making the same brittle and hard and extracting hydrogen by contacting oxygen with the surface of the treated metal while hot.
WALLACE NELSON MAYHEW.-
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US671303A US2057274A (en) | 1933-05-16 | 1933-05-16 | Process for heat treating ferrous metals |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US671303A US2057274A (en) | 1933-05-16 | 1933-05-16 | Process for heat treating ferrous metals |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2057274A true US2057274A (en) | 1936-10-13 |
Family
ID=24693941
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US671303A Expired - Lifetime US2057274A (en) | 1933-05-16 | 1933-05-16 | Process for heat treating ferrous metals |
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| US (1) | US2057274A (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2465773A (en) * | 1947-02-21 | 1949-03-29 | Du Pont | Process of producing a catalytic article |
| US3098151A (en) * | 1963-01-31 | 1963-07-16 | Inoue Kiyoshi | Electrical discharge of metals in electrolytes |
| US3147204A (en) * | 1960-02-25 | 1964-09-01 | Chemical Construction Corp | Anodic prevention of hydrogen embrittlement of metals |
| DE1177899B (en) * | 1961-04-13 | 1964-09-10 | Degussa | Process for nitriding metals, especially iron and iron alloys, in salt baths containing alkali cyanides and alkali cyanates |
| US3188245A (en) * | 1960-08-15 | 1965-06-08 | Inoue Kiyoshi | Electric discharge heat treatment of metals in electrolytes |
| US3198675A (en) * | 1960-08-15 | 1965-08-03 | Inoue Kiyoshi | Electric discharge heat treatment of metals in electrolytes |
| DE1227306B (en) * | 1961-05-31 | 1966-10-20 | Degussa | Process for nitriding metals, especially iron and iron alloys, in salt baths containing alkali cyanides and alkali cyanates |
| US3467585A (en) * | 1964-05-28 | 1969-09-16 | Jacques Jean Caubet | Method for treating steel by electrolysis in a molten thiocyanate |
| US3481839A (en) * | 1963-10-21 | 1969-12-02 | Inoue K | Method of depositing substances on and diffusing them into conductive bodies under high-frequency electric field |
-
1933
- 1933-05-16 US US671303A patent/US2057274A/en not_active Expired - Lifetime
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2465773A (en) * | 1947-02-21 | 1949-03-29 | Du Pont | Process of producing a catalytic article |
| US3147204A (en) * | 1960-02-25 | 1964-09-01 | Chemical Construction Corp | Anodic prevention of hydrogen embrittlement of metals |
| US3188245A (en) * | 1960-08-15 | 1965-06-08 | Inoue Kiyoshi | Electric discharge heat treatment of metals in electrolytes |
| US3198675A (en) * | 1960-08-15 | 1965-08-03 | Inoue Kiyoshi | Electric discharge heat treatment of metals in electrolytes |
| DE1177899B (en) * | 1961-04-13 | 1964-09-10 | Degussa | Process for nitriding metals, especially iron and iron alloys, in salt baths containing alkali cyanides and alkali cyanates |
| DE1227306B (en) * | 1961-05-31 | 1966-10-20 | Degussa | Process for nitriding metals, especially iron and iron alloys, in salt baths containing alkali cyanides and alkali cyanates |
| US3098151A (en) * | 1963-01-31 | 1963-07-16 | Inoue Kiyoshi | Electrical discharge of metals in electrolytes |
| US3481839A (en) * | 1963-10-21 | 1969-12-02 | Inoue K | Method of depositing substances on and diffusing them into conductive bodies under high-frequency electric field |
| US3467585A (en) * | 1964-05-28 | 1969-09-16 | Jacques Jean Caubet | Method for treating steel by electrolysis in a molten thiocyanate |
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