DIFF Main Group
C21D 1/00 General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
Introduced: September 1968
IPC and CPC are identically structured here. All 15 subcodes exist in both systems.
4 shared codes have differing titles between IPC and CPC.
Child Classifications
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- C21D 1/02 Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation IPC+CPC Available in IPC and CPC
- C21D 1/04 with simultaneous application of supersonic waves, magnetic or electric fields IPC+CPC Available in IPC and CPC
- C21D 1/18 Hardening (C21D1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C21D1/62) +1 CPC IPC+CPC Available in IPC and CPC
- C21D 1/54 Determining when the hardening temperature has been reached by measurement of magnetic or electrical properties IPC+CPC Available in IPC and CPC
- C21D 1/68 Temporary coatings or embedding materials applied before or during heat treatment IPC+CPC Available in IPC and CPC
- C21D 1/74 Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material IPC+CPC Available in IPC and CPC
- C21D 1/82 Descaling by thermal stresses (mechanically B21, B23; chemically C23; electrolytically C25F1/00) IPC+CPC Available in IPC and CPC
- C21D 1/84 Controlled slow cooling (cooling-beds for metal rolling B21B43/00) 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