IPC Main Group
C21D 9/00 Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
Introduced: September 1968
Last revised: January 2006
Classification Context
- Section:
- CHEMISTRY; METALLURGY
- Class:
- METALLURGY OF IRON
- Subclass:
- MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
Filing statistics
IPC C21D 9/00 belongs to the parent subclass C21D, which recorded 149,911 patent applications worldwide between 2013 and 2023. Annual filings grew from 9,561 in 2013 to 16,467 in 2023 (+72%), peaking at 16,959 applications in 2020. The most active applicants in class C21 are JFE STEEL (7,470 applications), POSCO (POHANG IRON AND STEEL COMPANY) (4,615 applications) and JFE STEEL (4,538 applications).
Source: EPO PATSTAT, worldwide filings
Related Keywords
ANNEALING of metal articlesFURNACES for heat treatment of metals or particular articlesHARDENING of metal articlesHEAT TREATMENT of metal articlesgeneral methods of or devices for heat treatment of NON-FERROUS metals or alloysTEMPERING of metal articles
22 direct subcodes
Child Classifications
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- C21D 9/02 for springs
- C21D 9/04 for rails
- C21D 9/08 for tubular bodies or pipes
- C21D 9/16 for explosive shells
- C21D 9/18 for knives, scythes, scissors, or like hand cutting tools
- C21D 9/2 for blades for skates
- C21D 9/22 for drills; for milling cutters; for machine cutting tools
- C21D 9/24 for saw blades
- C21D 9/26 for needles; for teeth for card-clothing
- C21D 9/28 for plain shafts
- C21D 9/3 for crankshafts; for camshafts
- C21D 9/32 for gear wheels, worm wheels, or the like
- C21D 9/34 for tyres; for rims
- C21D 9/36 for balls; for rollers
- C21D 9/38 for roll bodies
- C21D 9/4 for rings; for bearing races
- C21D 9/42 for armour plate
- C21D 9/44 for equipment for lining mine shafts, e.g. segments, rings or props
- C21D 9/46 for sheet metals
- C21D 9/5 for welded joints
Top Applicants
Top 10 applicants by patent filingsfor class C21, 2013–2023, worldwide · Source: EPO PATSTAT
- JFE STEEL JP 7,470
- POSCO (POHANG IRON AND STEEL COMPANY) KR 4,615
- JFE STEEL 4,538
- NIPPON STEEL CORPORATION JP 4,536
- ARCELORMITTAL LU 2,597
- NSSMC (NIPPON STEEL & SUMITOMO METAL) JP 2,241
- ANGANG STEEL COMPANY 2,126
- NSSMC (NIPPON STEEL & SUMITOMO METAL) 1,783
- BAOSHAN IRON & STEEL COMPANY 1,620
- HYUNDAI STEEL COMPANY KR 1,545