METALLURGY OF IRON

Description

C21 encompasses the extraction, processing, and refining of iron from ores and scrap materials, including pig iron production, steel manufacture, and cast iron processing. This class covers blast furnace operations, steelmaking processes (such as open hearth, electric arc, and oxygen conversion methods), and heat treatment of iron-based materials. It also includes surface treatment, mechanical working, and quality control of iron and iron alloys, but excludes non-ferrous metallurgy and the detailed composition or properties of specific steel grades, which are covered by materials science classifications.

Filing statistics

CPC C21 recorded 155,210 patent applications worldwide between 2013 and 2023, summed across its 3 subclasses. Annual filings grew from 8,172 in 2013 to 15,706 in 2023 (+92%), peaking at 17,553 applications in 2020. The most active applicants in class C21 are JFE STEEL (8,270 applications), NIPPON STEEL CORPORATION (5,222 applications) and POSCO (POHANG IRON AND STEEL COMPANY) (4,824 applications).

Source: EPO PATSTAT, worldwide filings