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 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 C23C)