CPC Main Group
C21D 9/00 Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
34 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 9/20 for blades for skates
- C21D 9/22 for drills; for milling cutters; for machine cutting tools
- C21D 9/24 for saw blades
Top Applicants
Top 10 applicants by patent filingsfor 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