|  | C |
SECTION C — CHEMISTRY AND METALLURGY

METALLURGY

|  | C21 |
METALLURGY OF IRON

|  | C21B |
MANUFACTURE OF IRON AND STEEL

|  | C21B |
Note(s) This sub-class covers the pretreatment of iron ores, production of pig-iron, blast furnaces, and air heaters.

|  | C21C |
PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON AND STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS (refining metals in general Fulltext... Hierarchy... Expanded...C22B 9/00)

|  | C21D |
HARDENING AND ANNEALING OF STEEL, IRON, OR ARTICLES MADE THEREFROM; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING MALLEABLE BY DECARBURISATION, TEMPERING, OR OTHER TREATMENTS (cementation by diffusion processes Fulltext... Hierarchy... Expanded...C23C)