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IPC Subclass
C21C

PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS

Introduced: September 1968

Classification Context

Section:
CHEMISTRY; METALLURGY
Class:
METALLURGY OF IRON
Subclass:
PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS

Description

C21C covers the refining of pig iron and the production of wrought iron and steel through various metallurgical processes, including treatment of ferrous alloys in their molten state. This subclass encompasses converters, furnaces, and processing methods designed to remove impurities and adjust chemical composition to achieve desired steel grades and properties. Technologies include basic oxygen processes, electric arc furnace operations, ladle metallurgy, and related thermal and chemical treatments. The scope extends to ferroalloy processing and molten metal handling techniques essential to modern steelmaking, but excludes mining, ore preparation, and the initial production of pig iron in blast furnaces (covered under C21B).

Filing statistics

IPC subclass C21C recorded 36,789 patent applications worldwide between 2013 and 2023. Annual filings grew from 2,651 in 2013 to 4,505 in 2023 (+70%). 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

Additional Content

Glossary

Pig-iron intermediate product of smelting iron ore with a high-carbon fuel, e.g. coke, charcoal Wrought-iron iron alloy with low carbon content and fibrous inclusions Tuyères tubes, nozzles or pipes through which air is blown into a furnace

Limiting references

Treating molten metals during moulding , Making liquid steel by direct processes

Related Keywords

making steel ALLOYSDESULFURISING of metalsproduction of steel otherwise than by direct processesrefining of IRONsteelREFINING of iron(1) as an alloy

4 direct subcodes

Child Classifications

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  • C21C 3/00 Manufacture of wrought-iron or wrought-steel

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