Making spongy iron or liquid steel, by direct processes

Introduced: September 1968

Last revised: January 2006

Classification Context

Section:: CHEMISTRY; METALLURGY
Class:: METALLURGY OF IRON
Subclass:: MANUFACTURE OF IRON OR STEEL

Filing statistics

IPC C21B 13/00 belongs to the parent subclass C21B, which recorded 31,098 patent applications worldwide between 2013 and 2023. Annual filings grew from 2,313 in 2013 to 3,647 in 2023 (+58%), peaking at 3,970 applications in 2022. 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

Related Keywords

making steel ALLOYSspongy IRON

7 direct subcodes

Child Classifications

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C21B 13/02 in shaft furnaces
C21B 13/04 in retorts
C21B 13/06 in multi-storied furnaces
C21B 13/08 in rotary furnaces
C21B 13/1 in hearth-type furnaces
C21B 13/12 in electric furnaces
C21B 13/14 Multi-stage processes

Top Applicants

Top 10 applicants by patent filingsfor 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