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MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHER TREATMENTS ( cementation by diffusion processes C23C; surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass, C23F 17/00 ; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
Definition statement
This subclass/group covers:

Changing the physical structure of ferrous metals; General devices for heat treatments of ferrous or non-ferrous metals or alloys; making metal malleable by decarburisation, tempering or other treatments

The term "ferrous alloys" refers to alloys based essentially on iron.

Relationship between large subject matter areas
  • C22F provides for decarburization of non-ferrous metal and non-ferrous alloys to modify the physical structure thereof.
  • Subclass C22B covers the decarburization of metalliferous material for purposes of refining.
  • C23F 17/00 provides for surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered in C22F.
  • When the method is intended for providing a particular use/product then the use/ product is classified as well (see informative references for some of them).
  • When the composition of the alloy is disclosed, either in claims or description, this one is classified as well C22C.
References relevant to classification in this subclass
This subclass/group does not cover:
Mechanical metal-working
Working metallic powder, powder metallurgical apparatus or processes
Changing the physical structure of non-ferrous metals or alloys
Surface treatment of metallic material
Cementation by diffusion processes
Electrolytic production or refining of metals
Single crystals or homogeneous polycrystalline material with defined structure; production thereof
Informative references
Attention is drawn to the following places, which may be of interest for search:
Layered products
Furnaces
Investigating or analysing material by determining their chemical or physical properties
Electric heating
Special rules of classification within this subclass
  • In C21D the last place rule is followed (classification in the last appropriate place) combined with multiple classifications, for a classification of a 100% disclosed alloy composition.
  • When classifying in group C21D 6/00, any aspect of the method for the heat treatment of ferrous alloys which is considered to represent information of interest for search may also be classified in groups C21D 1/02 - C21D 1/84. This can, for example, be the case when it is considered of interest to enable searching of heat treatment methods of ferrous alloys using a combination of classification symbols. Such non-obligatory classification should be given as "additional information".
  • When classifying in C21D all essential features disclosed should be classified in EC classification while all special features disclosed in claims, description, examples and figures/diagrams should be classified in M21D.
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Alloy
A composition of plural elements at least one of which is a free metal. It also includes material containing any combination of fibres, filaments, whiskers and particles, e.g. carbides, diamond, oxides, borides, nitrides, silicides, or other metal compounds, e.g. oxynitrides or sulfides embedded in a metallic matrix
Cast iron
Ferrous alloy which solidifies with an eutectic, with C 2.1-4%.
Steel
Ferrous alloy with a carbon content C 0.2-2.1%.
Air hardening steel
Steel which does not require quenching from a high temperature to harden but which is hardened by cooling in air from above its critical temperature range.
Sub-critical annealing/Stress relief annealing
Heat treatment for relieving or dissipating stresses in weldaments, heavily machined parts, castings, forgings by heating them, uniformly heated through, and air cooled/slow cooled with subsequent finishing or heat treatment.
Oil-hardening
Process of hardening a ferrous alloy by heating within or above the transformation range and quenching in oil
Decarburization
Subjecting the steel to high temperatures and heat treating in a media containing air, oxygen or hydrogen to remove carbon at the surface.
Recrystallization
After all metal crystals have been dissolved by heating enough to lose its structural strength, the metal temperature then falls, allowing the crystals to re-form
Spheroidizing
Heating the carbon steel to approximately 700 °C for over 30 hours to form spheroidite, to soften higher carbon steels and allow more formability.
Aging (or ageing)
A process in which the hardness or strength of a metal alloy having a constituent in supersaturated solid solution is increased over time as the constituent precipitates out as a secondary phase containing the constituent. When occurring at room temperature the process is termed "natural aging", while a process that occurs when subjecting the metal alloy to elevated temperature is termed "artificial aging". Aging for a longer time than that corresponding to maximum strength or hardness at the particular temperature is termed "over-ageing".
Hardening
The increase in resistance to deformation
Precipitation hardening
As the quenched alloy ages, a new material precipitates out of the metallic crystal lattice, filling in abutting spaces, and increasing hardness
Normalizing
A process of heating metallic material above its critical temperature and cooling in air thereby establishing a fine uniform grain size and improving the micro-structural uniformity
Quenching
The rapid cooling of metallic material either from elevated temperature to room temperature or cooling of metal to sub-ambient temperature, at a specific rate, with a given medium.
Tempering
Heating of a previously quenched or normalized metallic material to an elevated temperature, and then cooling under suitable conditions to obtain the desired mechanical properties.
Martempering
Heat treatment of steel involving austenitisation of steel followed by quenching in heat extracting medium (e.g. salt), at a rate fast enough to avoid the formation of ferrite, pearlite or bainite to a temperature slightly above the martensite start (Ms) point
Austempering
Isothermal heat treatment applied to steel and cast iron, involves holding the metallic material at the quenching temperature for an extended period of time in order to produce a lower bainite microstructure for steels and a structure of acicular ferrite and high carbon, stabilized austenite known as ausferrite for cast-irons.
Case Hardening
Heat treatment or combination of heat treatments of surface hardening involving a change in the composition of the outer layer of an iron-base alloy in which the surface is made harder by inward diffusion of a gas or liquid followed by appropriate thermal treatment.
General methods or devices for heat treatments, e.g. annealing, hardening, quenching, tempering ( furnaces in general F27 ; electric heating per se H05B)
Definition statement
This subclass/group covers:

Methods and devices for heat treatments: annealing, hardening, quenching of ferrous alloys.

Relationship between large subject matter areas

Ferrous alloys are classified in C22C 38/00.

When the heat-treated alloy is intended for a particular use/product then the use/ product is classified as well in the appropriate field/classes.

References relevant to classification in this group
This subclass/group does not cover:
Rolling of metal
Manufacture of metal sheets/bars/wires/tubes otherwise than by rolling
Forging
Cooling-beds for metal rolling
Coating material with metallic material, cementation (carburizing, nitriding, etc)/Chemical descaling
Processes for the electrolytic removal of materials from objects
Informative references
Attention is drawn to the following places, which may be of interest for search:
Machine tools; metal-working not otherwise provided for
Production of gases
Ferrous alloys
Furnaces
Heat exchange apparatus
Investigating or analysing material by determining their chemical or physical properties
Electric heating
Special rules of classification within this group

In these groups, the last place rule is followed combined with multiple classifications.

If the alloy composition is given it needs to be classified in C22C 38/00 in the corresponding sub-group(s).

All the disclosed heat treatments (claims, description, examples, figures/diagrams) are classified.

For example, a case hardened gear steel consisting of, by weight percent, 16.3Co, 7.5Ni, 3.5Cr, 1.75Mo, 0.2W, 0.11C, 0.03Ti, and 0.02V and the balance Fe, will be classified in this group in C21D 1/22 as well as in C22C 38/44, C22C 38/52.

Diffusion processes for extraction of non-metals; Furnaces therefor ( local protective coatings C21D 1/72 ; furnaces in general F27)
Definition statement
This subclass/group covers:

Diffusion processes for extraction of non-metals, furnaces thereof.

Relationship between large subject matter areas
  • Ferrous alloys are classified in C22C 38/00.
  • When the heat-treated alloy is intended for a particular use/product then the use/ product is classified as well in the appropriate field/classes, having also in mind group C21D 9/00.
References relevant to classification in this group
This subclass/group does not cover:
Rolling of metal
Manufacture of metal sheets/bars/wires/tubes otherwise than by rolling
Forging
Coating material with metallic material, cementation (carburizing, nitriding, etc)/Chemical descaling
Processes for the electrolytic removal of materials from objects
Informative references
Attention is drawn to the following places, which may be of interest for search:
Production of gases
Local protective coatings
Alloys
Furnaces
Special rules of classification within this group
  • In these groups, the last place rule is followed combined with multiple classifications.
  • If the alloy composition is given it needs to be classified in C22C 38/00 in the corresponding sub-group(s).
  • All the disclosed heat treatments (claims, description, examples, figures/diagrams) are classified.
  • For example, a method for production of a surface-decarburized hot-rolled strip with the following composition C: 0.4-1.0%, Si: 0.1-0.5%, Mn: 0.3-1.2%,
  • P: <0.02%, S: <0.008%, Al: 0.01-0.05%, Cr: 0.1-0.5%, Ni: 0.1-0.4%, Mo: <50.1%, balance Fe will be classified in C21D 3/04, as well as in C21D 1/74, in C22C 38/02, C22C 38/04, C22C 38/06, C22C 38/40.
  • In case of a method for manufacturing oriented silicon steel: (in wt %): C 0.020-0.050%, Si 2.6-3.6%, S 0.015-0.025%, Al 0.008-0.028%, N 0.005-0.020%, Mn 0.15-0.5%, Cu 0.3-1.2%, balance Fe and inevitable impurities , involves smelting steel, refining molten steel, continuously casting steel to obtain slab, hot rolling, cold rolling, annealing and applying annealing separator and insulation coating on slab, the classification in this group is: C21D 3/04, C21D 1/26, as well as C22C 38/001, C22C 38/02, C22C 38/04, C22C 38/06, C22C 38/16.
Heat treatments of cast-iron
Definition statement
This subclass/group covers:

Heat treatments of cast iron alloys - ferrous alloy which solidifies with an eutectic, with C 2.1% -4%.

Relationship between large subject matter areas
  • Cast iron is classified in C22C 37/00.
  • When the heat-treated cast iron alloy is intended for a particular use/product then the use/ product is classified as well in the relevant class in the appropriate field/classes, having also in mind group C21D 9/00.
  • Making cast iron alloys are classified in C22C 33/08C22C 33/12.
References relevant to classification in this group
This subclass/group does not cover:
Heat treating of non-ferrous alloys
Informative references
Attention is drawn to the following places, which may be of interest for search:
Refining of metals
Making cast iron alloys
Steels
Special rules of classification within this group

In these groups, the last place rule is followed combined with multiple classifications.

If the alloy composition is given it needs to be classified in C22C 37/00 in the corresponding sub-group.

All the disclosed heat treatments (claims, description, examples, figures/diagrams) are classified.

For example, a surface hardening cast iron parts by degraphitizing a surface layer part of cast iron member and thereafter irradiating a laser beam or an electron beam on said surface will be classified in C21D 5/00, as well as C21D 3/04 and C21D 1/09.

Heat treatment of ferrous alloys
Definition statement
This subclass/group covers:

Heat treatment of ferrous alloys: iron based alloys and all types of steels (low alloy steels, dual-phase steels, tool steels, spring steels, maraging steels, stainless steels, ferritic, austenitic, martensitic, bainitic, pearlitic etc).

Relationship between large subject matter areas

When the alloy is produced by a specifically described method (examples, claims) then the method is classified as well (B22F, C23C, B23K, C25D, C25B, B22D, B21J, B21B, B21C etc).

Ferrous alloys are classified in C22C 38/00.

When the alloy is intended for a particular use/product then the use/ product is classified as well.

References relevant to classification in this group
This subclass/group does not cover:
Heat treating of non-ferrous alloys
Heat treating of cast irons
Informative references
Attention is drawn to the following places, which may be of interest for search:
Soldering/welding materials
Layered products
Special rules of classification within this group
  • In these groups, the last place rule is followed combined with multiple classifications.
  • Since the alloy composition is given it needs to be classified in C22C 38/00 in the corresponding sub-group(s).
  • Heat treatment of ferrous alloys/steels containing Ni (and no Cr) are classified in C21D 6/001 and C22C 38/08.
  • Heat treatment of ferrous alloys/steels containing Cr (and no Ni) are classified in C21D 6/002 and C22C 38/18-C22C 38/38.
  • Heat treatment of ferrous alloys/steels containing Cr and no Ni are classified in C21D 6/004 and C22C 38/40 - C22C 38/58.
  • All the disclosed heat treatments (claims, description, examples, figures/diagrams) are classified.

For example a case hardened gear steel having enhanced core fracture toughness includes by weight percent about 16.3Co, 7.5Ni, 3.5Cr, 1.75Mo, 0.2W, 0.11C, 0.03Ti, and 0.02V and the balance Fe, characterized as a predominantly lath martensitic microstructure essentially free of topologically close-packed (TCP) phases and carburized to include fine M2C carbides to provide a case hardness of at least about 62 HRC and a core toughness of at least about 50 ksiVin will be classified in C21D 6/004; C21D 6/007; C21D 6/02; C21D 6/04, and also in C21D 1/22, C21D 1/25 and C22C 38/44, C22C 38/52.

Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:

In those groups, the following terms (or expressions) are used with the meaning indicated:

Hardening by cooling below 0 degrees Celsius
Controlled cooling below 0 C in order to alter the material microstructure, and enhance its strength and wear properties
Modifying the physical properties of iron or steel by deformation ( apparatus for mechanical working of metal B21 , B23 , B24)
Definition statement
This subclass/group covers:

Cold working and hot working deformation process of iron and steel.

Relationship between large subject matter areas

When the iron/steel alloy is produced by a specifically described method (examples, claims) then the method is classified as well (B22F, C23C, B23K, C25D, C25B, B22D, B21J, B21B, B21C etc).

Ferrous alloys are classified in C22C 37/00, C22C 38/00.

When the iron/steel alloy is intended for a particular use/product then the use/ product is classified as well.

References relevant to classification in this group
This subclass/group does not cover:
Rolling of metal
Manufacture of metal sheets/bars/wires/tubes otherwise than by rolling
Forging
Informative references
Attention is drawn to the following places, which may be of interest for search:
Working or processing of sheet metal or metal tubes, rods, or profiles without essentially removing material; punching
Apparatus for mechanical working of metal
Ferrous alloys
Special rules of classification within this group
  • In these groups, the last place rule is followed combined with multiple classifications.
  • If the alloy composition is given it needs to be classified in C22C 38/00 in the corresponding sub-group.
  • All the disclosed heat treatments (claims, description, examples, figures/diagrams) are classified.

For example a high cleanliness spring steel useful in manufacturing a spring with SiO 2 -based inclusions being extremely controlled and excellent in fatigue properties is obtained by scalping -> patenting -> cold wire drawing working (wire drawing) -> oil tempering -> process equivalent to strain relieving annealing -> shot peening -> strain relieving annealing will be classified in C21D 7/04, C21D 7/06, as well as in C22C.

Modifying the physical properties by deformation combined with, or followed by, heat treatment ( hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D 1/02)
Definition statement
This subclass/group covers:

Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing processes of plates or strips, plates or strips for deep drawing, rods or wires, tubular bodies, articles with special electromagnetic properties

Relationship between large subject matter areas

When the alloy is intended for a particular use/product then the use/ product is classified as well.

Ferrous alloys are classified in C22C 37/00, C22C 38/00.

References relevant to classification in this subclass/group
This subclass/group does not cover:
Rolling of metal
Manufacture of metal sheets/bars/wires/tubes otherwise than by rolling
Forging
Hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation
Informative references
Attention is drawn to the following places, which may be of interest for search:
Working or processing of sheet metal or metal tubes, rods, or Profiles without essentially removing material; punching
Ferrous alloys
Special rules of classification within this subclass/group
  • In this maingroup, the last place rule is followed combined with multiple classifications.
  • If the alloy composition is given it needs to be classified in C22C 38/00 in the corresponding sub-group.
  • All the disclosed heat treatments (claims, description, examples, figures/diagrams) are classified.
{of ferrous alloys (C21D 8/02 to C21D 8/12 take precedence ) }
Definition statement
This subclass/group covers:

Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys, during manufacturing of plates or strips.

Relationship between large subject matter areas

When the alloy is intended for a particular use/product then the use/ product is classified as well.

Ferrous alloys are classified in C22C 37/00, C22C 38/00.

References relevant to classification in this subgroup
This subclass/group does not cover:
Rolling of metal
Manufacture of metal sheets/bars/wires/tubes otherwise than by rolling
Forging
Hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation
Informative references
Attention is drawn to the following places, which may be of interest for search:
Working or processing of sheet metal or metal tubes, rods, or Profiles without essentially removing material; punching
Ferrous alloys
Special rules of classification within this subgroup
  • C21D 8/02 to C21D 8/12 take precedence.
  • In these groups, the last place rule is followed combined with multiple classifications.
  • Since the alloy composition is given it needs to be classified in C22C 38/00 in the corresponding sub-group.
  • All the disclosed heat treatments (claims, description, examples, figures/diagrams) are classified.

For example a method of producing a surface-decarburised hot-rolled strip consisting of heating the strip from heat-treated steel: C: 0.4-1.0%, Si: 0.1-0.5%, Mn: 0.3-1.2%, P: <0.02%, S: <0.008%, Al: 0.01-0.05%, Cr: 0.1-0.5%,

Ni: 0.1-0.4%, Mo: <50.1%, the remainder being iron and unavoidable impurities, heating it while wound as an open coil within austenitizing temperature limits, keeping it incandescent in a carbon-free atmosphere for at least 90 minutes, in which the atmosphere absorbs carbon from the steel, and cooling at an accelerated rate is classified in: C21D 8/0257, C21D 1/74, C21D 3/04, C22C 38/02; C22C 38/04; C22C 38/06; C22C 38/40.

to produce plates or strips for deep-drawing
Definition statement
This subclass/group covers:

Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys, during manufacturing of plates or strips for deep-drawing.

Relationship between large subject matter areas

When the alloy is intended for a particular use/product then the use/ product is classified as well.

Ferrous alloys are classified in C22C 37/00, C22C 38/00.

References relevant to classification in this subgroup
This subclass/group does not cover:
Rolling of metal
Manufacture of metal sheets/bars/wires/tubes otherwise than by rolling
Forging
Hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation
Informative references
Attention is drawn to the following places, which may be of interest for search:
Working or processing of sheet metal or metal tubes, rods, or Profiles without essentially removing material; punching
Ferrous alloys
Special rules of classification within this subgroup
  • In these groups, the last place rule is followed combined with multiple classifications.
  • Since the alloy composition is given it needs to be classified in C22C 38/00 in the corresponding sub-group.
  • All the disclosed heat treatments (claims, description, examples, figures/diagrams) are classified.

For example a micro-alloyed low carbon steel strip C:0.04-0.08, Mn:0.15-2.0, Si:0.06-0.60, P:0.010 max, S:0.010 max, Cr:0.35 max, Ni:0.20 max, Mo: 0.25 max, Cu:0.20 max, Nb:0.012-0.070, V:0.02-0.03, Ti<=0.11, Al:0.025-0.050, N:0.0115 max, rest Fe, , for the production of finished pieces by cold pressing and shearing, obtained by hot rolling at temperature of the pre-strip temperature never lower than 900 DEG C in the steps preceding the final rolling, will be classified in C21D 8/0405; C21D 8/0415, C21D 8/0415, C21D 1/42, C22C 38/02, C22C 38/04; C22C 38/06; C22C 38/12.

during manufacturing of rods or wires
Definition statement
This subclass/group covers:

Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys, during manufacturing of rods or wires.

Relationship between large subject matter areas

When the alloy is intended for a particular use/product then the use/ product is classified as well.

Ferrous alloys are classified in C22C 37/00, C22C 38/00.

References relevant to classification in this subgroup
This subclass/group does not cover:
Rolling of metal
Manufacture of metal sheets/bars/wires/tubes otherwise than by rolling
Forging
Hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation
Informative references
Attention is drawn to the following places, which may be of interest for search:
Working or processing of sheet metal or metal tubes, rods, or Profiles without essentially removing material; punching
Ferrous alloys
Special rules of classification within this subgroup
  • In these groups, the last place rule is followed combined with multiple classifications.
  • Since the alloy composition is given it needs to be classified in C22C 38/00 in the corresponding sub-group.
  • All the disclosed heat treatments (claims, description, examples, figures/diagrams) are classified.

For example a method of producing a steel wire suitable for reinforcement bar consists of choosing a steel of composition in wt. percent: less than 0.22% C; less than 0.5% Si; less than 1.5% Mn; and 0.01-0.15% V or 0.01-0.15% Nb or 0.01-0.15% V+Nb in which the carbon equivalent is less than 0.45 %, where the steel wire is hot rolled from billet, quenched at the end of the hot rolling stand and finally wound on a bobbin will be classified in C21D 8/08, C21D 1/19, C22C 38/12 .

during manufacturing of tubular bodies
Definition statement
This subclass/group covers:

Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys, during manufacturing of tubular bodies.

Relationship between large subject matter areas

When the alloy is intended for a particular use/product then the use/ product is classified as well.

Ferrous alloys are classified in C22C 37/00, C22C 38/00.

References relevant to classification in this subgroup
This subclass/group does not cover:
Rolling of metal
Manufacture of metal sheets/bars/wires/tubes otherwise than by rolling
Forging
Hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation
Informative references
Attention is drawn to the following places, which may be of interest for search:
Working or processing of sheet metal or metal tubes, rods, or Profiles without essentially removing material; punching
Ferrous alloys
Special rules of classification within this group
  • In these groups, the last place rule is followed combined with multiple classifications.
  • Since the alloy composition is given it needs to be classified in C22C 38/00 in the corresponding sub-group.
  • All the disclosed heat treatments (claims, description, examples, figures/diagrams) are classified.

For example the manufacture of case-hardened steel pipe for machine structural components, involves making pipe from steel composition in mass percent, C: 0.1 - 0.25%, Si: 0.2 - 0.4%, Mn: 0.3 - 0.9%, P: at most 0.02%, S: 0.001 - 0.15%, Cr: 0.5 - 0.9%, Mo: 0.15 - 1%, Al: 0.01 - 0.1%, B: 0.0005 - 0.009%, N: less than 0.006%, and a remainder essentially of Fe, followed by subjecting the resulting steel tube to normalizing by soaking at a temperature of 880 - 980 DEG C followed by cooling at a cooling rate of at most 70 DEG C per minute, carrying out cold working of the normalized steel tube, and then annealing the cold worked steel tube at a temperature of 700 - 820 DEG C will be classified in: C21D 8/105; C21D 8/10; C21D 1/28; C21D 1/32; C21D 6/02; C21D 7/04; C22C 38/00.

during manufacturing of articles with special electromagnetic properties
Definition statement
This subclass/group covers:

Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys, during manufacturing of articles with special electromagnetic properties

Relationship between large subject matter areas

When the alloy is intended for a particular use/product then the use/ product is classified as well, see H01F 1/00.

Ferrous alloys are classified in C22C 37/00, C22C 38/00.

References relevant to classification in this subgroup
This subclass/group does not cover:
Rolling of metal
Manufacture of metal sheets/bars/wires/tubes otherwise than by rolling
Forging
Hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation
Informative references
Attention is drawn to the following places, which may be of interest for search:
Working or processing of sheet metal or metal tubes, rods, or Profiles without essentially removing material; punching
Ferrous alloys
Special rules of classification within this subgroup
  • In these groups, the last place rule is followed combined with multiple classifications.
  • Since the alloy composition is given it needs to be classified in C22C 38/00 in the corresponding sub-group.
  • All the disclosed heat treatments (claims, description, examples, figures/diagrams) are classified.

For example the production of grain oriented magnetic sheet used for core of electrical transformer, involving heating slab made of steel : Si 3 - 3.3 %,

Al 0.012 - 0.028 %, C 0.005 - 0.065 %, Cu 0.01 - 0.1 %, Mn 0.045 - 0.05 %, N 0.0035 - 0.0055%, S 0.015 - 0.023 %, Se 0 - 0.018 %, Sn 0.082 %, Fe balance at a temperature (T1), hot-rolling using rolling mill at a temperature (T2), heating at a temperature (T3)>(T2), cold-rolling, optionally annealing and performing primary recrystallization and secondary recrystallization will be classified in C21D 8/1211, C21D 8/1222, C21D 8/1255, C21D 8/1272, C21D 6/008, C22C 38/001, C22C 38/008, C22C 38/02, C22C 38/04, C22C 38/16.

Heat treatment, e.g. annealing, hardening, quenching, tempering, adapted for particular articles; Furnaces therefor ( furnaces in general F27)
Definition statement
This subclass/group covers:

Heat treatment, e.g. annealing, hardening, quenching, tempering, adapted for particular articles; Furnaces therefore.

Relationship between large subject matter areas

F27B provides for furnaces, kilns, ovens or retorts in general; open sintering or like apparatus.

F27D provides for details or accessories of furnaces, ovens or retorts, in so far as they are of kinds occurring in more than one kind of furnace.

References relevant to classification in this group
This subclass/group does not cover:
Manufacture of metal sheets/bars/wires/tubes otherwise than by rolling
Surface treatment of metallic material
Cementation by diffusion processes
Electrolytic production or refining of metals
Single crystals or homogeneous polycrystalline material with defined structure; production thereof
Informative references
Attention is drawn to the following places, which may be of interest for search:
Furnaces
Vehicle parts
Ferrous alloys
Steam turbines, turbine rotors Blades, turbine blades
Valve guides/valve seat inserts
Gas turbine plants
Bearings, shafts/crankshafts
Springs
Sliding member
Working rails, sleepers, baseplates, or the like, in or on the line; Machines, tools, or auxiliary devices specially designed therefor
Special rules of classification within this group
  • In these groups, the last place rule is followed combined with multiple classifications.
  • If the alloy composition is given it needs to be classified in C22C 38/00 in the corresponding sub-group.
  • For example a heat treatment method of manufacturing high carbon bearing steel having excellent abrasion resistance and fatigue resistance, a steel wire rod for high carbon bearing steel subjected to the heat treatment, a manufacturing method of the steel wire rod, high carbon bearing steel manufactured by the heat treatment and a soaking method of a steel bloom used for manufacturing the steel wire rod. The heat treatment method of bearings includes the steps of: quenching a bearing-shaped steel part containing, by weight, 0.5% to 1.20% carbon and 1.0% to 2.0% silicon; and partitioning the quenched steel part at a temperature ranging from Ms - 100 degrees C to Ms for at least 10 minutes, where Ms represents a temperature at which formation of martensite will start, will be classified in C21D 9/0075 (rod of limited length), C21D 9/38, C21D 9/40, C21D 1/19, C21D 1/32, C22C 38/02, C22C 38/04, C22C 38/34.
  • Similarly, a rod of unlimited length, respectively a large gauge high strength steel rod having a diameter of not less than 9 mm, is produced from high carbon steel containing, by weight percent, from 0.65 to 0.90% carbon and from 0.15 to 1.5% chromium capable of being drawn without subsequent heat treatment will be classified in C21D 9/525, C21D 8/06, C22C 38/18.
  • The case hardened gear steel (example group C21D 1/00- C21D 1/84) consisting of, by weight percent, 16.3Co, 7.5Ni, 3.5Cr, 1.75Mo, 0.2W, 0.11C, 0.03Ti, and 0.02V and the balance Fe, classified in C21D 1/22 as well as in C22C 38/44, C22C 38/52, M21 as C21D 1/25, will also be classified in C21D 9/32.
  • The method for production of a surface-decarburized hot-rolled strip with specific disclosed composition ( example group C21D 3/00- C21D 3/10) will be classified in C21D 3/04, C21D 1/74, the corresponding C22C 38/00 classes and in C21D 9/46 and C21D 9/48.
Modifying the physical properties by methods other than heat treatment or deformation
Definition statement
This subclass/group covers:

Modifying the physical properties by laser shock processing, ultrasonic treatment and other methods other than heat treatment or deformation.

Relationship between large subject matter areas

When the alloy is intended for a particular use/product then the use/ product is classified as well, see H01F 1/00.

Ferrous alloys are classified in C22C 37/00, C22C 38/00.

References relevant to classification in this subgroup
This subclass/group does not cover:
Modifying the physical properties by heat treatment or deformation
Informative references
Attention is drawn to the following places, which may be of interest for search:
Modifying the physical properties of iron and steel by deformation
Alloys
Abrasive or related blasting with particulate material
Special rules of classification within this group
  • In these groups, the last place rule is followed combined with multiple classifications.
  • If the alloy composition is given it needs to be classified in C22C 38/00 in the corresponding sub-group.
  • All the disclosed heat treatments (claims, description, examples, figures/diagrams) are classified.

For example a steel tube with excellent steam oxidation resistance and a method for producing the steel tube by shot peening the inner surface of the steel tube will be classified in C21D 10/005 as well as in C21D 7/06, the corresponding C22C 38/00 classes and circulated to B24C 1/00 group.

Process control or regulation for heat treatments ( controlling or regulating in general G05)
Definition statement
This subclass/group covers:

Control and regulation of heat treatments.

Relationship between large subject matter areas

When classifying in this group, the disclosed heat treatments and/or furnaces should also be classified in C21D in the corresponding group and, for furnaces, in F27 too.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Controlling or regulating in general
Special rules of classification within this group
  • In these groups, the last place rule is followed combined with multiple classifications.
  • All the disclosed heat treatments (claims, description, examples, figures/diagrams) are classified.

Example: a metal processing system for forming and heat treating of metal casing comprises process control temperature station upstream from heat treatment station and having temperature sensing device, with a controlled cooling, classified in C21D 1/84, C21D 9/0068 will be also classified in C21D 11/005.

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Last Modified: 10/11/2013