IPC 6 English version  C21D-C21D01100
SECTION C– CHEMISTRY; METALLURGY

C 21

METALLURGY OF IRON

C 21 D

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 C 23 C; surface treatment of metallic material involving at least one process provided for in class C 23 and at least one process covered by this subclass C 23 F 17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C 30 B)

Note

In this subclass, it is desirable to add the indexing codes of subclass C 22 K, relating to changing the physical characteristics of alloys. The indexing codes should be unlinked. [6]

1/

00

General methods or devices for heat treatments, e.g. annealing, hardening, quenching, tempering (furnaces in general F 27; electric heating H 05 B)

1/

02

. 

Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation

1/

04

. 

with simultaneous application of supersonic waves, magnetic or electric fields

1/

06

. 

Surface hardening

1/

08

. . 

with flames

1/

09

. . 

by direct application of electrical or wave energy; by particle radiation [3]

1/

10

. . . 

by electric induction [3]

1/

18

. 

Hardening (C 21 D 1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C 21 D 1/62) [3]

1/

19

. . 

by interrupted quenching [3]

1/

20

. . . 

Isothermal quenching, e.g. bainitic hardening [3]

1/

22

. . . 

Martempering [3]

1/

25

. . 

Hardening, combined with annealing between 300°C and 600°C, i.e. heat refining ("Vergüten") [3]

1/

26

. 

Methods of annealing

1/

28

. . 

Normalising

1/

30

. . 

Stress-relieving

1/

32

. . 

Soft annealing, e.g. spheroidising

1/

34

. 

Methods of heating (C 21 D 1/06 takes precedence)

1/

38

. . 

Heating by cathodic discharges

1/

40

. . 

Direct resistance heating

1/

42

. . 

Induction heating

1/

44

. . 

in heat-treatment baths

1/

46

. . . 

Salt baths

1/

48

. . . 

Metal baths

1/

50

. . . 

Oil baths

1/

52

. . 

with flames

1/

53

. . 

Heating in fluidised beds [3]

1/

54

. 

Determining when the hardening temperature has been reached by measurement of magnetic or electrical properties

1/

55

. 

Hardenability tests, e.g. end-quench tests (investigating or analysing materials by determining their chemical or physical properties, in general G 01 N) [3]

1/

56

. 

characterised by the quenching agents

1/

58

. . 

Oils

1/

60

. . 

Aqueous agents

1/

607

. . 

Molten salts [3]

1/

613

. . 

Gases; Liquefied or solidified normally gaseous material [3]

1/

62

. 

Quenching devices

1/

63

. . 

for bath quenching [3]

1/

64

. . . 

with circulating liquids (in general F 28 D) [3]

1/

667

. . 

for spray quenching [3]

1/

673

. . 

for die quenching [3]

1/

68

. 

Temporary coatings or embedding materials applied before or during heat treatment

1/

70

. . 

while heating or quenching

1/

72

. . 

during chemical change of surfaces

1/

74

. 

Methods of treatment in inert gas, controlled atmosphere, vacuum, or pulverulent material (production of gases C 01, C 10)

1/

76

. . 

Adjusting the composition of the atmosphere

1/

767

. . 

with forced gas circulation; Reheating thereof [3]

1/

773

. . 

under reduced pressure or vacuum [3]

1/

78

. 

Combined heat-treatments not provided for above

1/

82

. 

Descaling by thermal stresses (mechanically B 21, B 23, chemically C 23, electrolytically C 25 F)

1/

84

. 

Controlled slow cooling (cooling-beds for metal rolling B 21 B 43/00) [3]

3/

00

Diffusion processes for extraction of non-metals; Furnaces therefor (local protective coatings C 21 D 1/72; furnaces in general F 27)

3/

02

. 

Extraction of non-metals

3/

04

. . 

Decarburising

3/

06

. . 

Extraction of hydrogen

3/

08

. . 

Extraction of nitrogen

3/

10

. 

Furnaces therefor

5/

00

Heat treatments of cast-iron

5/

02

. 

improving the malleability of grey cast-iron

5/

04

. 

of white cast-iron

5/

06

. . 

Malleabilising

5/

08

. . . 

with oxidation of carbon

5/

10

. . . . 

in gaseous agents

5/

12

. . . . 

in solid agents

5/

14

. . . 

Graphitising

5/

16

. . . . 

Packing agents

6/

00

Heat treatment of ferrous alloys [2]

6/

02

. 

Hardening by precipitation [2]

6/

04

. 

Hardening by cooling below 0 C [2]

7/

00

Modifying the physical properties of iron or steel by deformation (apparatus for mechanical working of metal B 21, B 23, B 24, e.g. shot-peening B 24 C)

7/

02

. 

by cold working

7/

04

. . 

of the surface

7/

06

. . . 

by shot-peening or the like

7/

08

. . . 

by burnishing or the like

7/

10

. . 

of the whole cross-section, e.g. of concrete reinforcing bars

7/

12

. . . 

by expanding tubular bodies

7/

13

. 

by hot working

8/

00

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 C 21 D 1/02) [3]

8/

02

. 

during manufacturing of plates or strips (C 21 D 8/12 takes precedence) [3]

8/

04

. . 

to produce plates or strips for deep-drawing [3]

8/

06

. 

during manufacturing of rods or wires [3]

8/

08

. . 

for concrete reinforcement [3]

8/

10

. 

during manufacturing of tubular bodies [3]

8/

12

. 

during manufacturing of articles with special electromagnetic properties [3]

9/

00

Heat treatment, e.g. annealing, hardening, quenching, tempering, adapted for particular articles; Furnaces therefor (furnaces in general F 27)

9/

02

. 

for springs

9/

04

. 

for rails (apparatus for heat treatment of railway rails on the spot E 01 B 31/18)

9/

06

. . 

with diminished tendency to become wavy

9/

08

. 

for tubular bodies or pipes

9/

10

. . 

shotgun barrels

9/

12

. . 

barrels for ordnance

9/

14

. . 

wear- or pressure-resistant pipes

9/

16

. 

for explosive shells

9/

18

. 

for knives, scythes, scissors, or like hand cutting tools

9/

20

. 

for blades for skates

9/

22

. 

for drills; for milling cutters; for machine cutting tools

9/

24

. 

for saw blades

9/

26

. 

for needles; for teeth for card-clothing

9/

28

. 

for plain shafts

9/

30

. 

for crankshafts; for camshafts

9/

32

. 

for gear wheels, worm wheels, or the like

9/

34

. 

for tyres; for rims

9/

36

. 

for balls; for rollers

9/

38

. 

for roll bodies

9/

40

. 

for rings; for bearing races

9/

42

. 

for armour plate

9/

44

. 

for equipment for lining mine shafts, e.g. segments, rings, props

9/

46

. 

for sheet metals

9/

48

. . 

deep-drawing sheets

9/

50

. 

for welded joints

9/

52

. 

for wires; for strips

9/

54

. . 

Furnaces for treating strips or wire

9/

56

. . . 

Continuous furnaces for strip or wire

9/

567

. . . . 

with heating in fluidised beds [3]

9/

573

. . . . 

with cooling [3]

9/

58

. . . . 

with heating by baths

9/

60

. . . . 

with induction heating

9/

62

. . . . 

with direct resistance heating

9/

63

. . . . 

the strip being supported by a cushion of gas [3]

9/

64

. . . 

Patenting furnaces

9/

66

. . . 

Tower-type furnaces

9/

663

. . . 

Bell-type furnaces [3]

9/

665

. . . . 

inverted or side-facing [3]

9/

667

. . . . 

Multi-station furnaces [3]

9/

67

. . . . . 

adapted for treating the charge in vacuum or special atmosphere [3]

9/

673

. . . . 

Details, accessories, or equipment peculiar to bell-type furnaces [3]

9/

675

. . . . 

Arrangements of charging or discharging devices [3]

9/

677

. . . . 

Arrangements of heating devices [3]

9/

68

. . . 

Furnace coilers; Hot coilers (cold coilers B 21 C)

9/

70

. 

Furnaces for ingots, i.e. soaking pits

10/

00

Modifying the physical properties by methods other than heat treatment or deformation [3]

11/

00

Process control or regulation for heat treatments (controlling or regulating in general G 05) [2]
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