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 [Search a list of Patent Appplications for class 420]   CLASS 420,ALLOYS OR METALLIC COMPOSITIONS
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SECTION I - CLASS DEFINITION

STATEMENT OF CLASS SUBJECT MATTER

This is the generic class for alloys containing metal or metallic compositions which contain a continuous phase of metal and methods of making same not provided elsewhere. This class will also take "elemental" metal, per se.

RULES OF PATENT PLACEMENT

Patents have been placed in this class employing the so called "genus-species" rule. Following this rule as between a generic subclass and its indents a species unprovided for in any indented subclass is specifically classified in the generic subclass. Thus a patent containing claims to both a provided for and an unprovided for species is placed as an original in the generic subclass as the first appearing subclass and cross-referenced to the indented subclass forthe provided for species.

The primary basis of classification in this class is the elemental composition of the alloy, or metallic composition without regard to the method of incorporation, or the state of the element in the product. As to impurities, a substance which is recited as optionally present as an impurity, e.g., "up to a certain percent", or "not over a certain percent" has been disregarded for purposes of classification. Thus, when searching for an alloy, or metallic composition containing a very small quantity of an ingredient consideration should be given to the possibility that the ingredient might have been disclosed as being an impurity and classified as if it were not present. If, however, an element is claimed as an impurity but is recited as being positively present in at least some minimum amountthis element is considered to be a positive constituent of the product and classified accordingly. In subclasses 8+ hereunder some subclasses contain limitations as to the percentages of an element present. When an alloy falls exactly on the recited percentage whether or not the alloy is included depends on the wording of the subclass limitation. If the subclass recites "X percent or more" than exactly X percent is included, if the subclass recited "more than "X percent" then exactly X percent is excluded. As examples compare subclass 34, "9 percent or more chromium containing" with subclass 94 "over 10 percent nickel containing". An alloy containing exactly 9 percent chromium is included under subclass 34 whereas an alloy containing exactly 10 percent nickel is excluded form subclass 94.

SECTION II - LINES WITH OTHER CLASSES AND WITHIN THIS CLASS

CHEMICAL COMPOUND AND COMPOSITION CLASSES (NONMETALLURGICAL).

In general, a composition called an alloy and containing metal is prima facie proper for this class (420) unless other disclosure positively reveals it to be properly classified elsewhere. A disclosure that nonmetallic particles are bonded by metal will be taken to denote a continuous phase of metal proper for Class 420 absent specific disclosure to the contrary. Cases of doubt as to whether a continuous phase of metal exists will be resolved in favor of placement in Class 420. A so called alloy which contains no metal is excluded from Class 420 and classified as a composition based upon its use or function. See References to Other Classes, below for classes speficially related to Nonmetallurgical Chemical Compound and Composition Classes.

The rules for determining Class placement of the Original Reference (OR) for claimed chemical compositions are set forth in the Class Definition of Class 252 in the section LINES WITH OTHER CLASSES AND WITHIN THIS CLASS, subsection COMPOSITION CLASS SUPERIORITY, which includes a hierarchical ORDER OF SUPERIORITY FOR COMPOSITION CLASSES.

METALLURGICAL AND METALLIC STOCK CLASSES

Class 420 provides for alloys, or metallic compositions which are intended to be of generally uniform character thought. While perfect uniformity is very difficult to achieve, this class (420) will take products which are not completely uniform where the intent is to produce a practically uniform product and any nonuniformity is accidental, or incidental and is not desired, or intended to give the product advantageous properties. Where a nonuniform product is desired, or intended, e.g., differing composition, or properties in different portions, etc., the product is considered to be stock and classified as appropriate in Classes 148, or 428 as discussed below.

This order of superiority among various metal, alloy, and metal stock areas and methods of manufacture involving them is as follows.

1. Class 419, Powder Metallurgy Processes.

2. Class 148, Metal Treatment, subclasses 22+, compositions for treatment of solid metal.

3. Class 75, Specialized Metallurgical Processes, Compositions for Use Therein, Consolidated Metal Powder Compositions, and Loose Metal Particulate Mixtures, subclasses 300, 301, and 303+, gaseous, liquid, or solid treating compositions for liquid metal or charges, and subclass 302, welding rod defined by composition.

4. Class 75, subclasses 228+, consolidated metal powder compositions and subclasses 255+, loose metal particulate mixtures.

5. Class 420, Alloys or Metallic Compositions, claimed as products.

6. Class 148, subclasses 95-122, 194-287, and 500-714, in the schedule order, providing for certain processes of treating solid or semi-solid metal by modifying or maintaining the internal physical structure (i.e., microstructure) or chemical properties of metal, processes of reactive coating of metal or processes of chemical-heat removing (e.g., flame-cutting, etc.) or burning of metal. However, if metal casting, fusion bonding, machining, or working is involved, there is a requirement of significant heat treatment as described in the Class 148 definition.

7. Class 148, subclasses 33+ barrier layer stock material and subclasses 400+, stock.

8. Class 75, subclasses 331+, processes of making solid partiuclate alloys directly from liquid metal and subclasses 343+, processes of producing or purifying alloys in powder form.

9. Class 75, subclasses 10.1+ and 10.67, processes of making alloys by electrothermic, electromagnetic, or electrostatic processes.

10. Class 420, Alloys or Metallic Compositions, processes of manufacture.

11. Class 75, subclasses 330+, processes of making metal and processes of treating liquid metals and liquid alloys and consolidating metalliferous material.

12. Class 204, Chemistry: Electrical and Wave Energy, processes.

13. Class 164, Metal Founding, subclasses 1+, processes.

14. Class 266, Metallurgical Apparatus, subclasses 44+, processes of operating metallurgical apparatus.

This list is not complete and may be added to as the proper relationship of other areas is determined.

See References to Other Classes, below for classes speficially related to Metallurgical And Metallic Stock Classes.

ARTICLE CLASSES.

The former rule known as the alloy "rule" has been abolished. Patents claiming an article by name only without any positive structural limitation and reciting the alloy, or metallic composition of which the article is made are properly classifiable in this class (420). This is true whether, or not the alloy, or metallic composition is claimed, per se, or whether it has specific properties making it particularly suitable for such article. There are, however, some article areas which have not yet as of 1981 been brought into conformance with this line. For these exceptions note is made to the list in the class definition of Class 106, Composition: Coating or Plastic, under (1) Note, section (b).

See References to Other Classes, below for classes speficially related to Article Classes.

SECTION III - REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:

75Specialized Metallurgical Processes, Compositions for Use Therein, Consolidated Metal Powder Compositions, and Loose Metal Particulate Mixtures,   subclasses 303+ for solid treating compositions for liquid metal or a charge for producing metal or treating liquid metal. The compositions in subclasses 303+ do not encompass alloys or metallic compositions, per se, even if used as treating agents. Another ingredient utilized in producing or refining or metal must by present with the alloy or metallic composition to be acceptable to these composition subclasses. An alloy or metallic composition made by consolidating base metal particles or a mixture or metal and nonmetal particles is proper for Class 75, subclasses 303+ or subclasses 228+ unless (a) all the components are melted or dissolved or (b) a part of the components are melted and the mass is treated as a fluent liquid (e.g., stirring, pouring, etc.) in which instances the product is proper for Class 420. Cases of doubt will be resolved in favor of placement in Class 75, subclasses 303+ or subclasses 228+. Class 75, subclasses 303+ or subclasses 255+ provide for compositions containing loose metal particles not elsewhere provide for. Class 420 provides for a free metal or a single ally or metallic composition in particulate form. However, a blend of free metal particles or alloy or metallic composition particles with other particles whether another free metal, another alloy or metallic composition, or a nonmetal is proper for Class 75, subclasses 303+ or subclasses 255+. Class 420 also provides for patents claiming an article by name only without any positive structural limitation and reciting the metal or alloy metallic composition of which the article is made. Processes of making solid particulate alloys or metallic compositions directly from liquid metal will be found in Class 75, subclasses 331+ and processes of producing alloys or metallic composition in powder form will be found in Class 75, subclasses 343+. In the instances in which the above mentioned processes are claimed and a process of making an alloy is claimed in generalized terms the patent will go as an original to Class 75 and a cross reference will be placed in Class 420. Processes of making an alloy by electrothermic, electromagnetic, or electrostatic steps will be found in Class 75, subclasses 10.1+ or subclass 10.67. In the instances in which the electrothermic, electromagnetic, or electrostatic steps are claimed and a process of making an alloy is claimed in generalized terms the patent will go as an original to Class 75 and a cross reference will be placed in Class 420. In the instances in which the electrothermic, electromagnetic or electrostatic steps are claimed and an alloy or metallic composition is claimed as a product the patent will go as an original to Class 420 and a cross reference will be placed in Class 75. The line between Class 75 and Class 420 is necessarily a difficult one since the metals produced by the processes of Class 75 are often impure and the Class 420 alloys are sometimes made from ores. Therefor, the following lines will be observed. A process of making an alloy of desired compositions for an end use will be classified in Class 420 even if made by reducing compounds or ore. A method of reduction or smelting to yield metal without intent to obtain a particular alloy or metallic composition will be classified in Class 75, even if it is recognized that the product is impure. Furthermore, methods of melting, refining, or purifying an existing alloy will be placed in Class 75. (Metallurgical and Metallic Stock Classes.)
106Compositions: Coating or Plastic,   for plastic compositions containing metal, or alloy fillers, or pigments and subclass 290 for pigment compositions containing metal alloy powders. This class (420) however, provides for an alloy, or metallic composition, per se, in powdered form even though claimed as a pigment. wder compositions containing a free metal. (Chemical Compound And Composition Classes-Nonmetallurgical)
148Metal Treatment,   appropriate subclasses for processes of treating solid or semi-solid metal to modify or maintain the internal physical structure (i.e., microstructure) or chemical properties of metal. If metal casting, fusion bonding, machining, or working is involved, there is a requirement of significant heat treatment as defined in the Class 148 definition. Note that Class 420 is superior and thus when both Class 420 claims to an alloy, or metallic composition, per se, and Class 148 process claims are present in the same patent, the original is placed in Class 420 with cross-reference in Class 148. Class 148, subclass 24 , is the location for a mixture of a powdered alloy or metallic composition with particles of a flux. Class 148, subclasses 400+, is the location for elemental metal, alloy or metallic compositions which (a) are the product of a process of Class 148, e.g., significantly heat treated, age hardened, etc., (b) are claimed in terms of specific magnetic properties, (c) are amorphous, (d) possess the property of shape memory, (e) are the product of a significant Class 164, Metal Founding step, e.g., chill cast, directionally solidified, etc., or (f) are the product of the dispersion of particulate matter in molten metal, which, particulate mater retains its identity in the final product, e.g., dispersion strengthened, etc. Class 420 provides for an alloy or metallic composition in which the claims include a recitation of physical, or chemical properties such as noncorrosiveness, hardness, of ductility which are inherent properties of the composition. Since Class 420 is superior, a patent containing both types of alloy or metallic composition claims is classified originally in Class 420 and cross-referenced to Class 148, subclasses 400+. Please note, in general no cross-references based on disclosures have been made from Class 148, subclasses 400+, stock, to Class 420 except from Class 148, subclasses 402, 403, and 404. Thus, for a complete search of possible unclaimed disclosure of alloys by composition, consideration should be given to expanding the search to the appropriate areas of Class 148, subclasses 300+ for magnetic stock material which is claimed as resulting from a Class 148 treatment or for stock material claimed in terms of a specified magnetic property, (e.g., coercive force, etc.). Class 420, however, provides for alloys or metallic compositions defined only as "magnetic", "magnetized", or "permanent magnet" material even though disclosed as resulting from a Class 148 treatment as well as alloys, or magnetic compositions claimed, per se, which are inherently magnetic. (Metallurgical and Metallic Stock Classes.)
164Metal Founding,   for a method of casting molten metal including the step of alloying while teaming (pouring), or in the mold. Otherwise a combined method of preparing an alloy followed by casting thereof is proper for Class 420. (Metallurgical and Metallic Stock Classes.)
204Chemistry: Electrical Wave Energy,   subclass 293 for electrodes for electrolytic devices claimed by name only and defined by the alloy, or metallic compositions of which they are made. (Article Class)
205Electrolysis: Processes, Compositions Used Therein, and Methods of Preparing the Compositions,   especially subclasses 334+ for electrolytic synthesis of an alloy or metallic composition. If, however, the alloy or metallic composition is also claimed as such, the patent is placed originally in Class 420 and cross-referenced to Class 205. (Chemical Compound And Composition Classes-Nonmetallurgical)
252Compositions,   subclass 1 for miscellaneous compositions not having a utility provided for elsewhere in the composition classification; subclass 62.3 for barrier layer device compositions. This class (420) however, provides for an alloy, or metallic composition, per se, which is a barrier layer composition; subclasses 62.51+ for magnetic compositions. This class (420), however, provides for an alloy, or metallic composition, per se, which is inherently magnetic, or is defined in terms of its magnetic properties. (Chemical Compound And Composition Classes-Nonmetallurgical)
266Metallurgical Apparatus,   for apparatus useful in preparing a Class 420 alloy. For related apparatus classified elsewhere see the search notes to Class 266. (Metallurgical and Metallic Stock Classes.)
423Chemistry of Inorganic Compounds,   for methods of storage of hydrogen by combination with an alloy no matter by what mechanical, whether chemical reaction, or sorbtion, and whether or not a stiochrometric compound is formed. This class (420) provides for an alloy, or metallic composition, per se, disclosed, or claimed as useful for binding hydrogen for purposes of storage no matter whether by chemical reaction, or sorbtion. (Chemical Compound And Composition Classes-Nonmetallurgical)
428Stock Material or Miscellaneous Articles,   for structurally defined stock material or blanks made wholely, or partially of metal. Consult the Class 428 definition for a detailed description of the structure proper for that class. Particularly pertinent subclasses are: subclasses 544+ , for stock which is all metal, or contains adjacent metals. Subclass 545 for metallic stock which contains a continuous phase of metal interengaged with a continuous phase of nonmetal. Subclass 615 for composite metal stock having plural, adjacent spatially distinct metal components e.g., layers, welded joint, etc. For this and indented subclasses there must be a sharp gradation between the plural components. Where there is a gradual gradation of properties, e.g., differentially heat treated etc., see Class 148, subclasses 400+. (Metallurgical and Metallic Stock Classes.)
430Radiation Imagery Chemistry: Process, Composition, or Product Thereof,   for an alloy, or metallic composition claimed, or solely disclosed as useful in a method of that class (430), particularly subclasses 85+ for alloys useful for use as photoconductors in electric photography, e.g., xerography, etc. (Chemical Compound And Composition Classes-Nonmetallurgical)
501Compositions: Ceramic,   for so called alloys which contain no metal and which have the properties, e.g., hard refractory, etc., associated with ceramic compositions. (Chemical Compound And Composition Classes-Nonmetallurgical)
506Combinatorial Chemistry Technology: Method, Library, Apparatus,   for a library (e.g., chemical, biological, etc.) or a process of creating said library.
523and 524 Synthetic Resin or Natural Rubbers,   for compositions containing a metal, alloy, or metallic composition as a pigment, or filler in a synthetic resin matrix, or continuous phase. (Chemical Compound And Composition Classes-Nonmetallurgical)

SECTION IV - GLOSSARY

Asterisked * terms are employed in section C, Chemistry and Metallurgy of the International Patent Classification (IPC) and have the same meaning herein.

The following is a list of synonyms of names of metals used in this class (mostly obsolete). They are followed in parenthesese by the metal names used in this class.

Synonym Name used herein

Aldebaranium (Ytterbium)

Austrium (Gallium (ipure))

Cassiopeium (Lutecium)

Celtium (Lutecium)

Demonium (Dyprosium)

Didymium (Mixture of neodymum and paraseodymum)

Dwi-manganese (Rhenium)

Eka-aluminum (Gallium)

Eka-boron (Scandium)

Eka-cesium (Virginum)

Eka-Iodine (Astatine)

Eka-manganese (Technetium)

Eka-silicon (Germanium)

Eka-tantalum (Protoactinum)

Erythronium (Vanadium)

Florentium (Promethium)

Glucinum (Beryllium)

Illinium (Promethium)

Masurium (Technetium)

Neoytterbium (Ytterbium)

Niobium (Columbian (Note: while niobium is the interna­tionally standard name among chemists, colu­mbium is still widely used among metallurgists in the USA)).

Tungsten (Wolfram (Note: while wolfram is the internationally standard name among chemists, tungsten is still preferred among metallurgists in the USA)).

ALKALI METAL*

A metal of the groups Lithium, Sodium, Potassium, Rubidium, Cesium and Francium.

ALKALINE EARTH METAL*

A metal of the group Calcium, Strontium, Barium and Radium.

ALLOY

A union, possessing metallic properties of two or more metallic elements, or of nonmetallic element(s) and metallic element(s) which are not pure compounds and which are miscible with each other, at least to a certain extent when molten, to form a more, or less homogeneous liquid having a metallic matrix and which do not separate into distinct layers when solid. Such combinations when solidified from a melt may consist of mechanical mixtures, entectics, entectoids, solid solutions, or in part of chemical compounds one, or more of which may exist at the same time. Intermetallic compounds are considered alloys for purposes of classification.

BASE

A metal which is present in an amount of over 50 percent by weight in an alloy, or metallic composition.

LANTHANIDE*

An element of atomic number 57 to 71 inclusive.

METAL*

Element other than nonmetal (q.v.)

METALLIC COMPOSITION

A composition which contains a continuous phase of metal and no continuous phase of nonmetal.

NOBLE METAL*

A metal of the group Ruthenium, Rhodium, Palladium, Osmium, Iridium, Platinum, Gold and Silver.

NONMETAL*

An element of the group, Hydrogen, Boron, Carbon, Silicon, Nitrogen, Phosphorus, Oxygen, Sulfur, Selenium, Tellurium, Fluorine, Chlorine, Bromine, Iodine, Astatine, Helium, Neon, Argon, Krypton, Xenon and Radon.

PRECIOUS METAL

Synonym for Noble Metal*

RARE EARTH*

An element of the group Scandium, Yttrium and the Lanthanides*.

REFRACTORY METAL*

A metal of the group Titanium, Zirconium, Hafnium, Vanadium, Niobium, Tantalum, Chromium, Molybdenum and Tungsten.

TRANSITION METAL*

An element of atomic number 21-30, 39-48 or 57-80.

SUBCLASSES

[List of Patents for class 420 subclass 1]    1Radioactive:
 This subclass is indented under the class definition.  Alloys or metallic composition which is claimed as being radioactive, containing an isotope of an element of which is radioactive or containing an element of which all known isotopes are radioactive.
(1) Note. The elements of which all known isotopes are radioactive are technetium, promethium and all elements of atomic number 84 and higher.
  
[List of Patents for class 420 subclass 2]    2Actinide base singly or in combination:
 This subclass is indented under subclass 1.  Alloy or metallic composition in which contains over 50 percent of a single metal of atomic number 89 to 103 inclusive, or wherein the total of all these metals taken together is over 50 percent of weight of the total alloy or metallic composition.
  
[List of Patents for class 420 subclass 3]    3Uranium base:
 This subclass is indented under subclass 2.  Alloy or metallic composition which contains over 50 percent uranium.
  
[List of Patents for class 420 subclass 4]    4Iron base:
 This subclass is indented under subclass 1.  Alloy or metallic composition which contains over 50 percent iron.
  
[List of Patents for class 420 subclass 5]    5Magnesium base:
 Alloy or metallic composition under subclass I which contains over 50 percent magnesium.
  
[List of Patents for class 420 subclass 6]    6Nickel or cobalt base:
 This subclass is indented under subclass 1.  Alloy or metallic composition which contains over 50 percent nickel or over 50 percent cobalt.
  
[List of Patents for class 420 subclass 7]    7Aluminum base:
 This subclass is indented under subclass 1.  Alloy or metallic composition which contains over 50 percent aluminum.
  
[List of Patents for class 420 subclass 8]    8Ferrous (i.e., iron base):
 This subclass is indented under the class definition.  Alloy or metallic composition containing over 50 percent of iron.
(1) Note. This and indented subclasses will take so called ferralloys e.g., ferrosilicon, etc., where the percentage of iron is not specified. Where there are indented subclasses hereunder which provide for different percentages of alloying ingredient e.g., chromium, the patent is classified in the subclass providing for the largest percentage of alloying ingredient in the absence of recitations that a smaller percentage is present.
  
[List of Patents for class 420 subclass 9]    91.7 percent or more carbon containing:
 This subclass is indented under subclass 8.  Alloy or metallic composition which additionally contains 1.7 percent or more carbon.
(1) Note. This and indented subclasses contain patents drawn to graphitic steel.
  
[List of Patents for class 420 subclass 10]    10Six percent or more total group IV, V, or VII transition metals containing:
 This subclass is indented under subclass 9.  Alloys or metallic composition which additionally contains 6 percent or more total content of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, or tungsten, singly or in combination.
(1) Note. Many patents in this and indented subclasses are so called "hard facing" alloys, which contain a high concentration of hard carbide precipitates.
  
[List of Patents for class 420 subclass 11]    11Eight percent or more chromium containing:
 This subclass is indented under subclass 10.  Alloy or metallic composition which additionally contains 8 percent or more of chromium.
  
[List of Patents for class 420 subclass 12]    12Molybdenum, tungsten or vanadium containing:
 This subclass is indented under subclass 11.  Alloy or metallic composition which additionally contains one or more of molybdenum, tungsten or vanadium.
  
[List of Patents for class 420 subclass 13]    132.7 percent or more carbon equivalent containing:
 This subclass is indented under subclass 9.  Alloy or metallic composition in which the total of the carbon content plus one third the silicon content plus one sixth the phosphorus content is 2.7 percent or more, i.e., cast iron.
(1) Note. The recitation "cast iron" shall be taken a indicating a carbon equivalent of 2.7 percent or more in the absence of a specific disclosure to the contrary.
  
[List of Patents for class 420 subclass 14]    14Boron containing:
 This subclass is indented under subclass 13.  Alloy or metallic composition which additionally contains boron.
  
[List of Patents for class 420 subclass 15]    15Chromium containing:
 This subclass is indented under subclass 13.  Alloy or metallic composition ... which additionally contains chromium.
  
[List of Patents for class 420 subclass 16]    16Nickel containing:
 This subclass is indented under subclass 15.  Alloy or metallic composition which additionally contains nickel.
  
[List of Patents for class 420 subclass 17]    17Molybdenum:
 This subclass is indented under subclass 16.  Alloy or metallic composition additionally contains molybdeum.
  
[List of Patents for class 420 subclass 18]    18Process of adding magnesium:
 This subclass is indented under subclass 13.  Processes of preparing an alloy or metallic composition wherein magnesium is added to the alloy or metallic composition.
(1) Note. The magnesium is usually added to cause carbon in the molten alloy to precipitate in spherical form, thus increasing the strength and ductility of the solid alloy, i.e., production of so called "nodular iron" or "spherulitic cast iron" etc.
  
[List of Patents for class 420 subclass 19]    19Adding magnesium as a liquid, vapor or as a solid agent entrained by a gas (e.g., fluidized):
 This subclass is indented under subclass 18.  Process of adding magnesium to an alloy or metallic composition where the magnesium is added in molten form as a liquid, is vaporized and added to the alloy metallic composition in the gaseous state or wherein a solid agent containing magnesium is entrained in a gas and added to the alloy or metallic composition while so entrained.
(1) Note. The recitation that a solid magnesium additive is added in a "fluidized" state renders a patent appropriate for this subclass.
  
[List of Patents for class 420 subclass 20]    20Flowing molten iron alloy onto solid magnesium containing agent, or adding solid magnesium containing agent to molten stream of iron alloy:
 This subclass is indented under subclass 18.  Process wherein a molten stream of iron alloy is poured onto a solid magnesium containing agent, e.g., in the bottom of a vessel, or wherein a solid magnesium containing agent is added to a molten stream of iron alloy, e.g., by continuously adding particles of agent to the molten stream.

SEE OR SEARCH CLASS:

164Metal Founding,   appropriate subclasses for similar processes wherein the solid magnesium containing agent is placed in a mold, followed by pouring molten iron, or wherein the molten iron is recited as being treated by a solid magnesium containing agent while being poured into a mold.
  
[List of Patents for class 420 subclass 21]    21Mechanically plunging magnesium containing agent below surface of iron alloy melt:
 This subclass is indented under subclass 18.  Processes wherein the magnesium containing agent is mechanically forced below the surface of the iron alloy melt, e.g., by employing a plunging bell.
  
[List of Patents for class 420 subclass 22]    22Separate addition of plural agents, at least one containing magnesium:
 This subclass is indented under subclass 18.  Process wherein plural agents of different compositions are separately added to an alloy or metallic compositions under subclass 13, at least one of the agents containing magnesium.
(1) Note. The additions of plural agents may be separated by physical location or separated by time.
  
[List of Patents for class 420 subclass 23]    23Magnesium containing agent is coated, impregnated or compacted (e.g., briquetted, coated particles):
 This subclass is indented under subclass 18.  Processes wherein the magnesium is contained in an agent which is coated, impregnated or compacted e.g., briquettes.
  
[List of Patents for class 420 subclass 24]    24Magnesium present in agent only as a compound with a nonmetal:
 This subclass is indented under subclass 18.  Process wherein the magnesium is added to the iron alloy only as a compound with a nonmetal and the additive contains no metallic magnesium or alloy thereof.
(1) Note. To be classified in this subclass, there must be a positive disclosure that the magnesium compound decomposes or reacts to yield metallic magnesium in the iron alloy. In the absence of such disclosure a patent is classified elsewhere under subclasses 13+ as appropriate.
  
[List of Patents for class 420 subclass 25]    25In agent also containing silicon, rare earth or alkaline earth metal:
 This subclass is indented under subclass 18.  Processes wherein magnesium in the iron alloy in an agent which additionally contain at least one of silicon, scandium, yttrium, a lanthanide metal, calcium, strontium or barium.
  
[List of Patents for class 420 subclass 26]    26Copper containing:
 This subclass is indented under subclass 13.  Alloy or metallic composition which additionally contains copper.
  
[List of Patents for class 420 subclass 27]    27Nickel or molybdenum:
 This subclass is indented under subclass 13.  Alloy or metallic composition which additionally contains at least one of nickel or molybdenum.
  
[List of Patents for class 420 subclass 28]    28Over .1 percent aluminum containing:
 This subclass is indented under subclass 13.  Alloy or metallic composition which additionally contains more than 0.1 percent of aluminum.
  
[List of Patents for class 420 subclass 29]    29Processes:
 This subclass is indented under subclass 13.  Processes of manufacturing an alloy or metallic composition .
  
[List of Patents for class 420 subclass 30]    30Adding rare earth or alkaline earth metal:
 This subclass is indented under subclass 29.  Process which includes a step of adding one or more of scandium, yttrium, a lantanide metal, calcium, strontium or barium to the alloy or metallic composition.
  
[List of Patents for class 420 subclass 31]    31Adding sulfur, selenium or tellurium:
 This subclass is indented under subclass 29.  Process which includes a step of adding one or more of sulfur, selenium or tellurium to the alloy or metallic composition.
  
[List of Patents for class 420 subclass 32]    32Adding vanadium, titanium, niobium or zirconium:
 This subclass is indented under subclass 29.  Process which includes a step of adding one or more of vanadium, titanium, niobium or zirconium to the alloy or metallic composition.
  
[List of Patents for class 420 subclass 33]    33Adding silicon:
 This subclass is indented under subclass 29.  Process which includes a step of adding silicon to the alloy or metallic composition.
  
[List of Patents for class 420 subclass 34]    34Nine percent or more chromium containing:
 This subclass is indented under subclass 8.  Alloy or metallic composition which additionally contains 9 percent or more of chromium.
(1) Note. Many of the alloys classified in this and indented subclasses are called "stainless steel" because the presence of 9 percent or more chromium makes an iron base alloy relatively resistant to corrosion. The recitation that a ferrous alloy is a "stainless steel" will prima facie be taken is meaning that the alloy is properly classified in this or indented subclass in absence of a specific indication that the alloy does not contain 9 percent or more chromium.
  
[List of Patents for class 420 subclass 35]    35Noble metal containing:
 This subclass is indented under subclass 34.  Alloy or metallic composition which additionally contains one or more of silver, gold, ruthenium, rhodium, palladium, osmium, iridium or platinum.
  
[List of Patents for class 420 subclass 36]    36Cobalt containing:
 This subclass is indented under subclass 34.  Alloy or metallic composition which additionally contains cobalt.
  
[List of Patents for class 420 subclass 37]    37Molybdenum or tungsten containing:
 This subclass is indented under subclass 36.  Alloy or metallic composition which additionally contains at least one of molybdenum or tungsten.
  
[List of Patents for class 420 subclass 38]    38Nickel containing:
 This subclass is indented under subclass 37.  Alloy or metallic composition which additionally contains nickel.
  
[List of Patents for class 420 subclass 39]    39Copper containing:
 This subclass is indented under subclass 37.  Alloy or metallic composition which additionally contains copper.
  
[List of Patents for class 420 subclass 40]    40Rare earth containing:
 This subclass is indented under subclass 34.  Alloy or metallic composition which additionally contains at least one of scandium, yttrium or a lanthanide metal.
  
[List of Patents for class 420 subclass 41]    41Lead, bismuth, antimony, calcium, selenium or tellurium containing:
 This subclass is indented under subclass 34.  Alloy or metallic composition which additionally contains at least one of lead, bismuth, antimony, calcium or tellurium.
(1) Note. These materials are commonly added in small amounts to improve the machinability of the alloy.
  
[List of Patents for class 420 subclass 42]    42Over 0.05 percent sulfur, over 0.04 percent phosphorus or sulfur or phosphorus added in any amount to promote machinability:
 This subclass is indented under subclass 34.  Alloys or metallic composition which contains one or more of more than 0.05 percent sulfur or more than 0.04 percent phosphorus or which contain any amount of sulfur or phosphorus which is positively stated to be present to promote machinability of this alloy or metallic composition.
  
[List of Patents for class 420 subclass 43]    43Eight percent or more nickel containing:
 This subclass is indented under subclass 34.  Alloy or metallic composition which additionally contains 8 percent or more of nickel.
(1) Note. This amount of nickel usually renders the alloy austenitic.

SEE OR SEARCH THIS CLASS, SUBCLASS:

56,for austenitic stainless steel which contains less than 8 percent nickel but which contains manganese instead to bring the total of the two elements to over 8 percent.
  
[List of Patents for class 420 subclass 44]    44Over 2 percent manganese containing:
 This subclass is indented under subclass 43.  Alloy or metallic composition which additionally contains more than 2 percent of manganese.
  
[List of Patents for class 420 subclass 45]    45Copper containing:
 This subclass is indented under subclass 44.  Alloy or metallic composition which additionally contains copper.
  
[List of Patents for class 420 subclass 46]    46Molybdenum or tungsten containing:
 This subclass is indented under subclass 44.  Alloy or metallic composition which additionally contains one or more of molybdenum or tungsten.
  
[List of Patents for class 420 subclass 47]    47Group IV or V transition metal containing:
 This subclass is indented under subclass 46.  Alloy or metallic composition which additionally contains one or more of titanium, zirconium, hafnium, vanadium, niobium or tantalum.
  
[List of Patents for class 420 subclass 48]    48Group IV or v transition metal containing:
 This subclass is indented under subclass 44.  Alloy or metallic composition which additionally contains one or more of titanium, zirconium, hafnium, vanadium, niobium or tantalum
  
[List of Patents for class 420 subclass 49]    49Copper containing:
 This subclass is indented under subclass 43.  Alloy or metallic composition which additionally contains copper.
  
[List of Patents for class 420 subclass 50]    50Over 1.5 percent silicon containing:
 This subclass is indented under subclass 43.  Alloy or metallic composition which additionally contains more than 1.5 percent silicon.
  
[List of Patents for class 420 subclass 51]    51Group IV or V transition metal containing:
 This subclass is indented under subclass 50.  Alloy or metallic composition which additionally contains one or more of titanium, zirconium, hafnium, vanadium, niobium or tantalum.
  
[List of Patents for class 420 subclass 52]    52Molybdenum containing:
 This subclass is indented under subclass 43.  Alloy or metallic composition which additionally contains molybdenum.
  
[List of Patents for class 420 subclass 53]    53Group IV or V transition metal containing:
 This subclass is indented under subclass 52.  Alloy or metallic composition which additionally contains one or more of titanium, zirconium, hafnium, vanadium, niobium or tantaium.
  
[List of Patents for class 420 subclass 54]    54Group IV or V transition metal containing:
 This subclass is indented under subclass 43.  Alloy or metallic composition which additionally contains one or more titanium, zirconium, hafnium, vanadium, niobium or tantalum.
  
[List of Patents for class 420 subclass 55]    55Over 0.1 percent carbon containing:
 This subclass is indented under subclass 43.  Alloy or metallic composition which additionally contains more than 0.1 percent of carbon.
  
[List of Patents for class 420 subclass 56]    56Eight percent or more total nickel plus manganese containing:
 This subclass is indented under subclass 34.  Alloy or metallic composition which additionally contains a total quantity of nickel plus manganese of 8 percent or more.
(1) Note. When the alloy contains 8 percent or more manganese, nickel may be completely absent.
(2) Note. This amount of nickel plus manganese usually renders the alloy austentic.

SEE OR SEARCH THIS CLASS, SUBCLASS:

43,for authentic stainless steel which contains 8 percent or more nickel.
  
[List of Patents for class 420 subclass 57]    57Molybdenum or tungsten containing:
 This subclass is indented under subclass 56.  Alloy or metallic composition which additionally contains one or more of molybdenum or tungsten.
  
[List of Patents for class 420 subclass 58]    58Copper containing:
 This subclass is indented under subclass 56.  Alloy or metallic composition which additionally contains copper.
  
[List of Patents for class 420 subclass 59]    59Over 0.20 percent nitrogen containing:
 This subclass is indented under subclass 56.  Alloy or metallic composition which additionally contains more than 0.20 percent nitrogen.
  
[List of Patents for class 420 subclass 60]    60Copper containing:
 This subclass is indented under subclass 34.  Alloy on metallic composition which additionally contains copper.
  
[List of Patents for class 420 subclass 61]    61Molybdenum or tungsten containing:
 This subclass is indented under subclass 60.  Alloy or metallic composition which additionally contains one or more of molybdenum or tungsten.
  
[List of Patents for class 420 subclass 62]    62Over 0.1 percent aluminium containing:
 This subclass is indented under subclass 34.  Alloy or metallic composition which additionally contains more than 0.1 percent aluminum.
  
[List of Patents for class 420 subclass 63]    63Molybdenum or tungsten containing:
 This subclass is indented under subclass 62.  Alloy or metallic compositions which additionally contains more of molybdenum or tungsten.
  
[List of Patents for class 420 subclass 64]    64Boron containing:
 This subclass is indented under subclass 34.  Alloy or metallic composition which additionally contains boron.
  
[List of Patents for class 420 subclass 65]    650.25 percent or more nitrogen containing:
 This subclass is indented under subclass 34.  Alloy or metallic composition which additionally contains 0.25 percent or more nitrogen.
  
[List of Patents for class 420 subclass 66]    66Group IV or V transition metal containing:
 This subclass is indented under subclass 65.  Alloy or metallic composition which additionally contains one or more of titanium, zirconium, hafnium, vanadium, niobium or tantaium.
  
[List of Patents for class 420 subclass 67]    67Molybdenum or tungsten containing:
 This subclass is indented under subclass 34.  Alloy or metallic composition which additionally contains one or more of molybdenum or tungsten.
  
[List of Patents for class 420 subclass 68]    68Titanium, zirconium, or hafnium containing:
 This subclass is indented under subclass 67.  Alloy or metallic composition which additionally contains one or more of titanium, zirconium or hafnium..
  
[List of Patents for class 420 subclass 69]    69Vanadium, niobium or tantalum containing:
 This subclass is indented under subclass 67.  Alloy or metallic composition which additionally contains one or more of vanadium, niobium and tantalum.