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IPC Main Group
C21D 6/00

Heat treatment of ferrous alloys

Introduced: July 1974

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

Related Keywords

ANNEALING of ferrous alloysHARDENING of iron or steelHARDENING of other ferrous alloysHEAT TREATMENT of ferrous alloysheat treatment of alloys of IRONTEMPERING of other ferrous alloys

2 direct subcodes

Child Classifications

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Top Applicants

Top 10 applicants by patent filingsfor class C21, 2013–2023, worldwide · Source: EPO PATSTAT

  1. JFE STEEL JP 7,470
  2. POSCO (POHANG IRON AND STEEL COMPANY) KR 4,615
  3. JFE STEEL 4,538
  4. NIPPON STEEL CORPORATION JP 4,536
  5. ARCELORMITTAL LU 2,597
  6. NSSMC (NIPPON STEEL & SUMITOMO METAL) JP 2,241
  7. ANGANG STEEL COMPANY 2,126
  8. NSSMC (NIPPON STEEL & SUMITOMO METAL) 1,783
  9. BAOSHAN IRON & STEEL COMPANY 1,620
  10. HYUNDAI STEEL COMPANY KR 1,545