C21D 1/18 Hardening (C21D1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C21D1/62)
Introduced: September 1968
Title
Titles differ between systems:
IPC: Hardening; Quenching with or without subsequent tempering
CPC: Hardening (C21D1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C21D1/62)
Full Title
Full titles differ between systems:
General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering > Hardening; Quenching with or without subsequent tempering
General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering > Hardening (C21D1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C21D1/62)
Of 3 combined children, 2 exist in both systems.
1 codes are CPC-only extensions.
1 shared codes have differing titles between IPC and CPC.
IPC defines codes here since 1980.
Child Classifications
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- C21D 1/25 Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten") since 1980 IPC+CPC Available in IPC and CPC
Top Applicants
Top Applicants (IPC)
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
Top Applicants (CPC)
Class C21,2013–2023, worldwide · Source: EPO PATSTAT
- JFE STEEL JP 8,270
- NIPPON STEEL CORPORATION JP 5,222
- POSCO (POHANG IRON AND STEEL COMPANY) KR 4,824
- JFE STEEL 3,311
- ARCELORMITTAL LU 3,239
- NSSMC (NIPPON STEEL & SUMITOMO METAL) JP 2,659
- HYUNDAI STEEL COMPANY KR 1,492
- ANGANG STEEL COMPANY 1,318
- BAOSHAN IRON & STEEL COMPANY 1,233
- KOBE STEEL JP 1,228